Staff Assessment Report - EPA NZ

Staff Assessment Report

APP203542: An application to release two moths (Wheeleria spilodactylus and Chamaesphecia mysiniformis) as biological control agents for the weed horehound (Marrubium vulgare).

August 2018

Purpose To introduce two moths, Wheeleria spilodactylus and Chamaesphecia mysiniformis to

control the weed horehound (Marrubium vulgare).

Application number APP203542

Application type Notified, Full Release

Applicant Horehound Biocontrol Group

Date formally received 15 May 2018

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EPA advice for application APP203542

August 2018

Executive Summary and Recommendation

In May 2018, the Horehound Biocontrol Group made an application to the Environmental Protection Authority

(EPA) seeking to introduce two moths, Wheeleria spilodactylus (the plume moth) and Chamaesphecia

mysiniformis (the clearwing moth), as biological control agents for the weed horehound (Marrubium vulgare).

We assessed the benefits (positive effects) and risks and costs (adverse effects) of introducing the two

biocontrol agents to New Zealand and found that the benefits relating to environmental outcomes to be

significant and the adverse effects negligible (Kaser & Ode 2016).

We consider it likely that biological control of horehound will improve biodiversity values and conservation of

protected natural habitats. We also consider it highly likely that biocontrol of horehound will reduce the costs of

farming relating to crop replacement and wool processing. We note that this biocontrol programme could reduce

the dispersal of the weed into sensitive environments.

We consider it highly improbable for the plume moth and the clearwing moth to pose risks to native or valued

plants in New Zealand. There are no native species in the Marrubium genus and, no other valued species within

this genus in New Zealand. Host range experiments confirmed their narrow host specificity.

We also evaluated the possible indirect effects of the two agents, including apparent competition, and found it

very unlikely for the plume moth and the clearwing moth to have adverse impacts on ecosystems.

We consider the potential economic risks that may occur following the release of the biocontrol agents in New

Zealand and found that it is very unlikely that herbalists and their business interests would be adversely affected

by the release of the two agents.

The EPA staff assessment report also discusses the effects of the two insects on the relationship of Māori to

their environment, and measures the agents against the minimum standards in the Hazardous Substances and

New Organisms Act (HSNO Act). We conclude that the plume moth and the clearwing moth meet the minimum

standards.

Our assessment found the benefits of releasing the plume moth and the clearwing moth outweigh any identified

risks and costs and recommend that the application be approved.

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August 2018

Table of contents

Purpose of this document 4

Application process 4

Submissions 4

Submissions from DOC and MPI 4

The biology and ecology of Marrubium vulgare ……………………………...………………………………..5

Impact of horehound on the environment 6

Distribution/status of horehound around the world 7

Distribution in New Zealand 8

Current strategies to control horehound 9 Organisms proposed for release …………………………………………………………................................10

The native range and biology of the plume moth (Wheeleria spilodactylus) 10

The native range and biology of the clearwing moth (Chamaesphecia mysiniformis) 11

The impacts of plume moth and clearwing moth on horehound in Australia 11

Climate favourable for plume moth and clearwing moth establishment 12

Risk assessment ……………………………………………………………………………………………………..13 Assessment of benefits 14

Our assessment of the potential environmental benefits 14

Environmental benefits of horehound in the absence of the biocontrol agents 14

Environmental benefits of the two biocontrol agents 15

Our assessment of the potential economic benefits 17

Economic benefits of horehound in the absence of the biocontrol agents 17

Economic benefits of the two biocontrol agents 18

Assessment of risks 20

Our assessment of the potential environmental risks 20

Environmental risks of horehound in the absence of the biocontrol agents 20

Environmental risks of the two biocontrol agents 21

Our assessment of the potential economic risks 24

Economic risks of horehound in the absence of the biocontrol agents 24

Economic risks of the two biocontrol agents 24

Conclusion on benefits and risk assessment 27

Relationship of Māori to the environment ………………………………………………………………………28

Consideration of the Māori Reference Group 26

Consultation with Te Herenga 26

Minimum Standards …………………………………………………………………………...............................26

Additional matters to be considered 27

Recommendation ………………………………………………………………………….………………………...27

References 28

Internet references 32

Appendix 1: Summary of submissions 33

Appendix 2: Cultural Risk Assessment for New Organisms Application 40

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August 2018

Purpose of this document

1. On 15 May 2018, the Horehound Biocontrol Group applied to the Environmental Protection Authority

(EPA) to introduce two moths, Wheeleria spilodactylus and Chamaesphecia mysiniformis, as biological

control agents for the weed horehound (Marrubium vulgare).

2. This document has been prepared by EPA staff to advise the Decision-making Committee on our risk

assessment for the release of the moths. The document discusses the information provided in the

application, information readily available in scientific literature, and information submitted to the EPA

during the public notification process.

Application process

3. The Horehound Biocontrol Group lodged an application with the EPA on 15 May 2018 seeking approval

to release the two moths under section 34 of the Hazardous Substances and New Organisms (HSNO)

Act (the Act).

4. The application was publicly notified, and open for submissions for 30 working days on 29 May 2018 as

required by section 53(1)(b) of the Act. The submission period ended on 11 July 2018.

Submissions

5. We received forty submissions on this application. The submissions are summarised in Appendix 1.

Thirty-nine submitters including farmers, regional councils, and government agencies support the

application and one submitter, a herbal company, oppose the application. Eight submitters indicated

they wish to be heard.

Submissions from DOC and MPI

6. As required by the Act and the Hazardous Substances and New Organisms (Methodology) Order 1998,

the Ministry for Primary Industries (MPI) and the Department of Conservation (DOC) were notified of the

application and provided with the opportunity to comment.

7. MPI supports the application. They note the negative impact of chemicals on the environment and the

benefit that biocontrol agents offer in the long term. MPI recognises that the release of the two moth

species is unlikely to eradicate all horehound from New Zealand.

8. DOC supports the application due to the high host specificity of the moths and success of the two

agents against horehound in Australia, but do not support the general approach with the testing being

done in Australia. They would prefer to see testing being conducted on native New Zealand species and

not surrogate species only.

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August 2018

Horehound as the target weed

The biology and ecology of Marrubium vulgare

9. Horehound is a tall (25 to 60 cm) perennial herb in the mint family. Native to the temperate

Mediterranean region and central and western Asia, it is widely naturalised in the United States and

South America as well as Australia and New Zealand. It was introduced in Australia and elsewhere by

settlers as a useful garden herb, for beer brewing and for medical purposes. It most likely escaped

cultivation to rapidly become a major weed for pasture (Weiss et al. 2000).

10. Horehound has dense clusters of small white flowers that form brown burrs with small hooked spines.

Each burr contains four small spear-shaped seeds. The burr easily attaches itself to anything that comes

into contact (e.g. wool, fur, clothing, tyres) enabling effective seed dispersal. Water channels and horse

faeces are other effective natural dispersing agents for the seeds (Weiss et al. 2000).

11. Mature plants are multi-stemmed with up to 200 individual stems and can produce more than 20,000

seeds a year. The seeds stay viable for 7 to 10 years in the soil (Weiss et al. 2000). Horehound has the

ability to disperse effectively via rhizomes and seeds (Stritzke 1975). Most seeds germinate with the first

autumn rainfall and through winter. In spring, the plant flowers and is primarily bee-pollinated (Weiss &

Sagliocco 2011).

12. Horehound can grow in various climates from arid to high-rainfall zones (Weiss & Sagliocco 1994). It

thrives in disturbed areas like waste places, roadsides, along fence lines, fields extensively grazed by

sheep, as well as native grasslands where competition with other plants is limited (Weiss et al. 2000). It

is often the first plant to colonise eroded areas (Parsons et al. 2001). Horehound can be found in infertile

soils and is tolerant to drought and frost conditions. The soil moisture availability can be a limiting factor

for germination, however, mature plants seem to be able to survive dry conditions (Lippai et al. 1996).

Table 1: Complete taxonomic description of horehound

Taxonomic Unit Classification

Phylum/Division Spermatophyta

Class Dicotyledonae

Order Lamiales

Family Labiatae (formally known as Lamiaceae)

Sub-family Lamioideae

Genus Marrubium

Species vulgare

Common name horehound, white horehound, hoarhound, marrube, houndsbane

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August 2018

13. Due to the bitter taste of horehound, livestock avoid grazing the plant and focus on other species. Their

behaviour reduces the competition for horehound, which allows the weed to spread even further. If

animals are forced to eat it, due to the lack of alternative feed, their meat and milk become tainted

(Weiss et al. 2000; Parsons et al. 2001).

14. While a pest for farmers, horehound is also considered a therapeutic plant. Its medical properties have

been used for centuries in traditional medicine to treat various diseases including inflammatory,

gastroenteric and respiratory disorders (Parsons et al. 2001; Sahpaz et al. 2002; Stulzer et al. 2006).

Studies on the major components of the plant show that its biological activity could explain its anti-

inflammatory effects (Sahpaz et al. 2002). Horehound essential oil has proven potent antimicrobial

activity against pathogenic bacteria and fungi (Zarai et al. 2011).

Impact of horehound on the environment

15. Under favourable conditions, horehound can quickly colonise newly disturbed areas (Lippai et al. 1996)

and form dense monocultures (Weiss & Sagliocco 1994). Its efficient seed germination strategy and its

adaptability to different environmental conditions are characteristics of a troublesome weed (Benvenuti

et al. 2001). These factors support the invasive tendencies of horehound on pastures areas in Australia

and New Zealand.

16. The presence of native or introduced mammals in natural habitats can quickly lead to the establishment

and invasion of new areas (Sagliocco & Coupland 1995). However, we note that the plant is rarely a

problem in well-managed pasture and rarely persists in areas where competition from annual or

perennial pasture species arises.

17. Climate change is associated with drier summers, favouring the establishment of horehound as showed

by the recent drought in New Zealand (Cook, 2016). The plant appears to be a problem in areas

receiving between 200 mm and 400 mm annual rainfall (Lippai et al. 1996; Weiss 1996). Harsh climatic

conditions contribute to the decrease of other pasture species (Lippai et al. 1996). Furthermore, intense

grazing by sheep on other species, due to the unpalatable taste of horehound, create ideal conditions

for horehound to grow and invade pastoral areas (Weiss et al. 2000). Therefore, the areas most

impacted by the horehound weed are semi-arid states, like north-western Victoria and south-eastern

South Australia, and Otago and Canterbury in New Zealand.

18. In Victoria by 1980, 6 million ha were infested by horehound. The infestation also affected 3.5% of

conservation areas (Weiss & Scott 1996). The establishment of the weed put at risk some species like

the endangered marble daisy bush (Olearia astroloba) and the rare spiny lignum (Muehlenbeckia

horrida) (Weiss et al. 2000). In New Zealand, horehound has been observed in tussock grass where

threatened and naturally uncommon species are present (De Lange et al. 2004).

19. The increase of horehound in pastoral areas has a direct impact on livestock by reducing the amount of

food available, which increases the time required to reach slaughter weight.

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August 2018

20. The presence of horehound also affects wool quality and increases farmer costs by adding steps to the

cleaning process to eliminate burrs from fleeces (Parsons et al. 2001).

21. Spraying large areas infested by horehound helps manage infestations but this has a negative impact on

the other species. Furthermore, the use of herbicides increases the risk of erosion as soil becomes

exposed to the elements creating a favourable environment for the weed.

Distribution/status of horehound around the world

22. Horehound has been listed by the Pacific Island Ecosystems at Risk (PIER) as invasive in Australia,

China, six offshore islands of Chile, Hawaii, New Caledonia, South America, and in various Pacific

islands (PIER, 2013). The plant is also recognised as a weed in the USA and South America (Weiss &

Sagliocco 1994; Lippai et al. 1996; Groves 2002; CABI 2018). In 2003, a risk assessment, based on the

best information available at the time for Australia, indicated that horehound poses a high risk of

becoming a serious pest (Pacific Island Ecosystems at Risk, 2018).

23. In the USA horehound is found in 47 states (Plants that grow in the USA 2017). The plant is widely

established in arid salt deserts in North America, and thrives in the intermountain area of the western

United States where the soil was highly disturbed by extensive sheep grazing during the first part of the

20th century (Young & Evans 1986). However, it is classified as limited1 under the California Invasive

Plant Council due to its minor ecological impacts.

24. Horehound shows weedy potential in its native European region, yet it has limited impact on the

environment, occurring only in scattered and less dense infestations (Clarke 2001). In some part of

Europe, its decline is attributed to a change in land use practices in the agricultural and pastoral sectors,

as well as a decrease in grazing stock and land abandonment, which led to an increase in competition

for horehound plant (Khela 2013). Horehound is listed as a ‘near threatened’ species by the International

Union for Conservation of Nature.

25. In Australia, it is considered not only as a weed of pastures but also as an important environmental

weed (Weiss & Sagliocco 1994). Its impact is attributed to a combination of environmental and human

factors. Compared to Europe, Australia and New Zealand have different land management practices

using different grazing methods, the availability of various vectors to transport seed and the lack of

herbivorous insects provide an ideal environment for horehound to thrive.

26. Despite the higher soil seed bank of horehound in Australia compared to Europe (20,000 versus 1,000

per m²), the main reason for the differences in horehound populations between the two geographic

locations seems to be mainly attributed to the abundance of specific herbivorous insects and pathogens

in Europe that attack horehound (Weiss & Sagliocco 1994).

1 These species are invasive but their ecological impacts are minor on a state wide level or there was not enough information to justify a

high score. Their reproductive biology and other attributes result in low to moderate rates of invasiveness. Ecological amplitude and distribution are generally limited, but these species may be locally persistent and problematic.

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August 2018

Distribution in New Zealand

27. Marrubium vulgare arrived with settlers in the middle of the 19th century and was recorded as naturalised

in New Zealand in 1867 before being classified, for the first time, in 1902 as a weed (Groenteman &

Loxton 2016; Groenteman et al. 2017).

28. Horehound is found in low-rainfall parts of New Zealand where it forms dense stands in hill and high-

country. As shown on the map in Fig 1, horehound has spread in both islands and is more abundant in

the South Island. During the public consultation process we received more than 20 submissions from

farmers affected by the weed situated in the Otago and Canterbury regions.

29. The Horehound Biological Control Group is collecting information from farmers to have a better

understanding of how widespread horehound is, including how fast it is growing, the current cost of

controlling and the effectiveness of current control methods, as well as the chemical effects on

production-loss and pasture replacement. These results have not yet been published.

Figure 1: Distribution of Marrubium vulgare in New Zealand1

1 EPA acknowledges use of data drawn from the National Vegetation Survey Databank (NVS) website on 16 July 2018.

NVS does not guarantee that all data are error-free and records are typically not associated with voucher herbarium specimens. If any location records appear erroneous, please report these to NVS (https://nvs.landcareresearch.co.nz).

https://nvs.landcareresearch.co.nz/

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August 2018

Current strategies to control horehound

30. There are different methods to control horehound that depend on its abundance, the surface that needs

to be treated and how early the treatment is applied. Horehound can be controlled by physical, chemical,

or biological control.

31. In newly infested areas where the density is low and the infested zone small, the more efficient and

environmentally sustainable control method is by grubbing plants. By acting early, the plant does not

have the time to produce seeds and the control of horehound is more efficient in the long term. Slashing

will also limit the establishment of the plant by stopping seed production.

32. With dense infestations in small to medium areas, the use of fire can destroy mature plants and reduce

the soil seed bank by 80% (Weiss et al. 2000). However, this strategy will have to be carried out for a

number of years to ensure all seeds have been destroyed.

33. In areas where horehound has spread widely or is not easily accessible, the use of various herbicides

can help reduce the weed populations. With this method, the impact on non-target species needs to be

considered as chemicals can persist in the soil for a long period of time. Furthermore, and as reported

by many farmers in their submissions to the EPA, chemical controls appear ineffective and undesirable

in conservation or ecologically sensitives areas where the plant is or could become a serious threat

(Sagliocco & Coupland 1995).

34. After removal, sowing vigorous growing pasture and using adequate fertiliser can help to reduce the

next generation of horehound to emerge by increasing competition. However, fertilisation must be

carefully used as it can also be beneficial to other weed species (Dukes & Mooney 1999). In addition,

good livestock management systems will help reduce infestation by minimising the movement of sheep

from contaminated areas to clean paddocks.

35. The use of biocontrol agents can also help reduce the weed infestation. In 1994 and 1997, two

European insect species were released as biocontrol agents in Australia to control populations of

horehound: the horehound plume moth (Wheeleria spilodactylus), a defoliator suppressing large plants,

and the horehound clearwing moth (Chamaesphecia mysiniformis), a root borer attacking young plants.

36. Different methods of control are not incompatible but require some organisation to guarantee the best

results in the long term. Cooperation between neighbouring landholders is essential to ensure

successful control of the plant. Once an area has been treated it is necessary to make follow-up visits to

control new plants and guarantee the eradication of horehound from that area (Weiss et al. 2000). By

combining biocontrol with other methods, populations of horehound have been successfully reduced in

Australia. (Clarke et al. 2000).

37. Despite the combination of physical and chemical controls, horehound continues to spread through

sites frequented by tourists (e.g. camping spots) and waterways making it hard to manage in New

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Zealand. However, in Australia the use of horehound-specific self-dispersing biocontrol agents reaching

reservoir sites that represent a source of new plants helped to reduce new infestations (Clarke et al.

2000).

Organisms proposed for release

38. The Horehound Biocontrol Group seeks to release two moths, Wheeleria spilodactylus and

Chamaesphecia mysiniformis, as biological control agents for the weed horehound (Marrubium vulgare).

The native range and biology of the plume moth (Wheeleria spilodactylus)

39. The plume moth is approximately 10 mm long with a wingspan of 20 mm. This species is widespread in

central and southern Europe and around the Mediterranean sea from Turkestan to North Africa

(Menéndez & Thomas 2000). Table 2 shows the taxonomic classification of the species.

40. Female plume moths lay on average 100 eggs over a two-week period on the underside of young

horehound leaves during summer. After a week, the eggs hatch and the larvae start to feed on the

leaves, working their way down the shoot where they pupate over winter (Briese et al. 2007).

41. The first generation of adult plume moths emerges in spring, with a six to eight week lifecycle, allowing

up to three generations per year. The moth is active from October until April/May. The larvae will

overwinter in leaf buds, waiting for warmer weather to complete their life cycle (Briese et al. 2007).

Table 2: Taxonomic description of Wheeleria spilodactylus


Class Insecta

Order Lepidoptera

Family Pterophoridae

Genus Wheeleria

Species spilodactylus (Curtis, 1827)

Common names horehound plume moth or plume moth

42. Literature and host-specificity tests conducted for the purpose of an Australian release show that plume

moth host range is restricted to three species: white horehound (Marrubium vulgare), scallop shell (M.

supinum) and black horehound (Ballota nigra). However, black horehound is a poor secondary host

plant with low survival rates of the plume moth (Victorian Department of Conservation and Natural

Resources 1993; Menéndez & Thomas 2006). In areas where white and black horehound species are

present, more than 99% of the plume moth larvae were found on white horehound (Menéndez &

Thomas 2000).

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The native range and biology of the clearwing moth (Chamaesphecia mysiniformis)

43. The clearwing moth is relatively small with a wingspan from 11 to 24 mm. This species is less

widespread in Europe than the plume moth. It is found in Spain, Portugal, Italy, southern France and

Morocco under continental and Mediterranean-type climates (Weiss & Sagliocco 2011). Table 3 shows

the taxonomic classification of the species.

44. In spring, adults emerge from roots and females mate on the first day. Soon after, they lay around 90

eggs during a one to two week period. The eggs are deposited at the base of the plant. The larvae start

to feed on the outer cambium1 of the plant to find their way to the roots and spend the following months

feeding and developing within the roots before emerging as adults the following spring. Development

times seem to be determined by climatic conditions. In northern Europe, clearwing moths spend more

time in the roots than moths from central Europe (Sagliocco & Coupland 1995). Clearwing moths

produce only one generation of offspring per year (Bailey 2007).

45. The clearwing moth has a larger host range than the plume moth. Larvae have been found in several

genera of Lamiaceae (Marrubium, Stachys, Ballota, Sideritis) (Bailey 2007).

Table 3: Taxonomic description of Chamaesphecia mysiniformis


Class Insecta

Order Lepidoptera

Family Sesiidae

Genus Chamaesphecia

Species mysiniformis (Boisduval, 1840)

Common names horehound clearwing moth or clearwing moth

The impacts of plume moth and clearwing moth on horehound in Australia

46. In Europe, both moths play a role, together with other insects and pathogens, to maintain horehound

populations (Weiss & Sagliocco 1994). The absence of specific herbivorous insects in Australia and

New Zealand, as well as other factors, provided ideal conditions for horehound to spread and to become

a problem for farmers.

1 a thin formative layer between the xylem and phloem of most vascular plants that gives rise to new cells and is responsible

for secondary growth.

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47. Australia was the first country to use biological control for horehound infestation. After a 10-year

biocontrol research programme, the plume moth and clearwing moth were identified as being specific to

horehound and were approved for release (Weiss & Sagliocco 2011).

48. The two moths were observed to inflict significant damage to different parts of the horehound plant. The

plume moth larvae defoliate the stem, weakening the plant and reducing the production of flowers and

therefore the number of seeds limiting its dispersal (Weiss et al. 2000). The clearwing moth causes

mortality both directly, by disrupting vascular flow, and indirectly, through secondary infection by

pathogens (Sagliocco & Coupland 1995).

49. The plume moth was first released in 1994 in various sites in south-east Australia. In 1997, this was

followed by the release of an ecotype originating from arid regions and potentially more resistant to high

temperatures (Weiss & Sagliocco 2011). In 1998, the moth was established in 90% of release locations.

The presence of one or two larvae per shoot was observed and found more than 20 km away from the

site of original release (Weiss et al. 2000).

50. Clearwing moth was released two years later, in 1997, in Victoria and South Australia, followed by two

further releases the next year at the same site in Victoria. Monitoring is difficult as larvae only emerge

from roots when they become adults (Wills 2000). The establishment of the moth was confirmed in

2001. By 2003, more than 50% of the original release sites were infested by the larvae (Weiss &

Sagliocco 2011).

Climate favourable for plume moth and clearwing moth establishment

51. The Mediterranean climate, characterised by winter rains and dry hot summers, where both moths

originate from, is similar to the climate found in the southwestern parts of Australia (Weiss & Sagliocco

1994). In New Zealand, summers and winter are characterised by cooler temperatures and higher

rainfall compared to Australia. We have a temperate maritime climate. The successful establishment of

the two biocontrol agents is likely to depend on their capacity to adapt to the climate in the South Island

where horehound is the biggest problem. In 2009, one year after the release of eggs in Tasmania, a

clearwing moth pupa was discovered, suggesting that this biocontrol agent can establish under different

climatic conditions (Weiss & Sagliocco 2011). Despite Sagliocco and Coupland (1995) showing that the

clearwing moth was sensitive to temperature, requiring between 22°C and 37°C to mate, another study

concluded that the successful establishment of the plume moth in Australia was more dependent on the

quality and quantity of the horehound population than climate variations (Clarke 2001).

52. In Australia, the plume moth is now common in areas with rainfalls greater than 450 mm per year and

temperatures less than 35°C (Weiss et al. 2000), whereas, the clearwing moth, where the larvae

develop inside the roots, is found in drier areas (Clarke et al. 2000).

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Risk assessment

Risk assessment assumptions

53. Our assessment of the benefits and risks associated with the release of the plume moth and the

clearwing moth to control horehound is based on the assumption that both insects successfully establish

in the New Zealand environment and develop self-sustaining populations.

54. There is no risk if the two insects do not establish in New Zealand. Conversely, if either or both insects

establish large populations, the frequency of potential risks, discussed in our assessment below,

increases. At the same time, the benefits will also increase with larger populations since both insects will

need to reach high numbers to cause optimum damage to horehound populations in order to be

beneficial. Therefore, an assessment made on full establishment makes it easier to determine if the

benefits truly outweigh the risks or vice versa.

55. We note that the plume moth and the clearwing moth may take some time to establish self-sustaining

populations; therefore, the effects of the insects on horehound populations will be gradual at first.

56. The applicant considers that the release of the plume moth and the clearwing moth would have

significant beneficial effects on the environment, market economy, and on Māori and their relationship

with the environment, their culture and traditions.

57. We assessed the risks and benefits across five keys areas, and did not find that people and community

as well as public health will be directly affected by the introduction of the biocontrol agents. Therefore,

we focused our assessment on the environmental, economic, and Māori impacts.

58. We took into consideration anecdotal evidence, together with quantitative and qualitative information

available from farmers and farming organisations submitted as part of the application and during the

public submissions process. The effects of the two biocontrol agents in Australia helped us to assess the

potential impact of the moths on horehound in New Zealand.

59. For the purpose of our assessment, we compared the potential risks and benefits of not releasing the

two moths, thus retaining the status quo, with the release of the two agents in New Zealand (Table 4).

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Table 4: Risks and benefits with and without the introduction of the biocontrol agents (BCA).

Assessment of benefits

60. We have assessed all benefits but only discuss the effects that we considered significant. Therefore,

those effects where the magnitude or likelihood of occurrence is improbable or speculative, are not

included in our risk assessment.

Our assessment of the potential environmental benefits

Environmental benefits in the absence of the two biocontrol agents

61. In the absence of biocontrol agents, horehound abundance and infestations would increase. That may

facilitate the plant’s use in industrial applications that could benefit the environment.

Environmental benefits of horehound

62. Horehound is mainly known by herbalists and the public for its benefits on human health but it has other

characteristics that may help improve soil quality. Studies show that the plant can accumulate heavy

metals present in soil (Krupp et al. 2009). Therefore, horehound could be a candidate to decontaminate

areas that have been subject to mining. However, other plant species have higher absorption capacity,

for example the concentration of mercury found in the roots of wild asparagus (Asparagus acutifolius) is

Assessment of risks Assessment of benefits

Potential environmental risks

No BCA

More herbicide use

Less insect and flora biodiversity

BCA

Impact on non-target native or valued species

Affect food webs

Worse weeds may establish

Potential environmental benefits

No BCA

Decontamination of soil

BCA

Reduction in abundance of horehound at existing sites and less new sites invaded

Less herbicides

Improve biodiversity

Potential economic risks

No BCA

More herbicides

Increase cost of crops

Reduce productivity

Decrease wool value

BCA

Less herbage available

Potential economic benefits

No BCA

More herbage available for medicinal use

BCA

Less herbicides

Cost-effective

Increase in wool value

Increase of pasture productivity

Wild horehound still available

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five times higher than in horehound (Higueras et al. 2003). Similarly, arsenic, cadmium, copper and lead

in the environment have been shown to be more effectively remediated by onion weed (Asphodelus

fistulosus) (Guo et al. 2009).

63. Based on the information available, horehound is assessed to play a minor role to protect the

environment since other plants are known to more effectively remediate heavy metal contamination in

soils.

Environmental benefits of the two biocontrol agents

64. The applicant identified the following benefits of the plume moth and clearwing moth to the New Zealand

environment:

Reduced risk of invasion of horehound into new sites

Reduced adverse environmental consequences of controlling horehound using herbicides

65. The introduction of the two biocontrol agents would help reduce the populations of horehound to lower

densities in pastoral areas through a combination of actions that target different areas of the plant

(Ireson et al. 2000). Some geographically isolated unmanaged habitats could remain out of reach from

biocontrol agents with the lack of continuity of the weed plant (Ireson et al. 2000).

66. As a consequence of the actions of the moths, we consider that invasion of new sites will decrease.

There will also be less herbicide applications needed and biodiversity may improve where horehound

abundance decreases. Some unmanaged habitats could remain a source of untreated plants for

herbalists and the public.

Biological control of horehound is highly likely to limit the risk of invasion into new sites

67. The introduction of the two biocontrol moths in certain areas adversely impacted the numbers of flowers

and seeds of horehound in pastures in Australia. We can conclude that the reduction in the seed bank

automatically reduced the risk of dispersal of new plants by livestock and waterways.

68. Despite horehound having not yet reached its full weedy potential in New Zealand, the use of biocontrol

agents at an early stage might be more effective (Groenteman et al. 2017).

69. Once the biocontrol agents establish it is highly likely that invasion of new sites will decrease which

could have major beneficial effects on the environment since the spread to conservation land,

ecologically sensitive areas (e.g. tussock) and clean pastures would be limited.

Biocontrol of horehound is highly likely to reduce the use of herbicides

70. Herbicides are used to manage infestations of horehound in pastoral areas. Good results can be

obtained when herbicides are either applied in spring, before the plant flowers, or in autumn when the

plant is actively growing (Horehound Control Guide). Nevertheless, results are only temporary and more

plants emerge from the horehound seed bank the following year. Matthew Tayler, a farmer from

Southland, notes in his submission that despite all the effort put in to control the weed by grubbing and

using chemicals, more and more plants were observed as well as newly infested areas. Between 2017

and 2018, the area of infested lucerne that had to be treated more than doubled from 20 ha to 50 ha.

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August 2018

71. Whereas the use of herbicides helps to temporarily control horehound population, large-scale

applications are likely to damage indigenous vegetation and pastures sown by farmers. Similarly, the

use of biocontrol agents on their own would not provide complete control (McMillan 1990; Ainsworth

1999). Only an integrated weed control approach would limit or prevent the re-growth of horehound. The

release of the plume moth and the clearwing moth will be another tool to help control horehound

populations in New Zealand. In Australia, their introduction did not eradicate horehound but helped, in

combination with other methods such as herbicides, to reduce its impact on the environment

(Groenteman et al. 2017).

72. According to Ainsworth, spraying the plant in spring has a negative impact on the longevity and the

fecundity of adult plume moths due to the reduction in number of flowers (the main source of adult

moths’ food). Furthermore, females will seek non-treated horehound to deposit their eggs limiting the

impact of combined controls (Ainsworth 1999). Ainsworth noted that spraying before or after oviposition

with low toxicity herbicides, like 2,4-D, did not seem to impact eggs or larvae of plume moths.

73. When sprayed in autumn, herbicides have a lower impact on the biocontrol agents. Although up to 90%

of horehound are killed by herbicides, chemical controls would leave enough plants for the plume moth

population to survive and emerge the following spring (Weiss et al. 2000). In order to maximise the

survival of the biocontrol agents, the Cooperative Research Centre for Australian Weed Management

recommends leaving some patches untreated.

74. We consider that the use of the two moths would likely result in the reduction of herbicides that are

used in pastoral environments to control horehound. We consider that any beneficial effects would be

minor since reductions in herbicides may have localised environmental benefits in and around

horehound populations where biodiversity is low and collateral damage to native flora limited. However,

in the long-term, once the populations of horehound have been reduced to smaller patches in some

areas from the use of the biocontrol agents and other control methods and no longer represent a risk for

farmers, it is highly likely that less herbicide will be used.

Biocontrol of horehound is likely to improve biodiversity

75. Biocontrol agents released in unmanaged habitats would have higher beneficial effects on biodiversity

than in pastures dominated by monocultures. According to some submissions, horehound has always

been present but only started to become a problem with the increase in drought conditions and the

introduction of lucerne.

76. Horehound infestation in conservation areas could represent a risk to endemic plant species (see

paragraph 18). In Wyperfeld National Park Australia, Victoria, around 9000 ha were infested by

horehound. (Weiss 1996). In New Zealand, the two most infested regions, Otago and Canterbury, are

also the provinces containing the most threatened and uncommon plants in New Zealand (De Lange et

al. 2004). By reducing horehound abundance, biocontrol agents will support the establishment of other

plants in conservation estates and enhance biodiversity values. However, it is unlikely that indigenous

biodiversity would return without human intervention (Adair & Groves 1997). In order to avoid other

weeds sprouting in place of horehound, Edwards advised planting desirable species (Edwards 1974).

77. The applicant notes that the biocontrol agents will have a minor beneficial impact on high country

remnant indigenous flora where horehound grows.

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78. We conclude that the release of the two moths, together with human intervention, would likely reduce

horehound populations and improve native biodiversity. We consider that any beneficial effects on

biodiversity would be minor in pastoral areas, other modified habitats and unmanaged border areas,

whereas the benefits will be major to unmanaged habitats with high biodiversity.

Conclusion to the potential environmental benefits of biological control

79. We considered the potential environmental benefits that may occur following the release of the plume

moth and the clearwing moth in New Zealand and found that it is highly likely that biological control of

horehound will reduce infestations of new sites and likely reduce the amount of herbicides used. In the

long term, with successful control and minimal establishment of other weeds, it is highly likely that less

herbicide will be used. We note that the magnitude of future beneficial effects will be major where

horehound’s spread to conservation land and ecologically sensitive areas is curtailed, minor where the

moths successfully suppress horehound and reduce the application of herbicides, and minor to improve

biodiversity values in pastoral areas.

80. We consider the environmental benefits of the introduction of the two biocontrol agents will range from

low to high.

Our assessment of the potential economic benefits

Economic benefits of horehound in the absence of the biocontrol agents

81. We consider that the abundance and spread of horehound could increase economic benefits for

herbalists and the public by providing access to more herbage.

The medicinal use of horehound and increase in available herbage in the absence of biocontrol

82. Horehound is used in herbal preparations and the manufacture of medicinal beverages by herbalists. Its

natural properties have been supported by recent clinical research and medical studies (Yamaguchi et

al. 2006; Kadri et al. 2011; Radojević et al. 2013; Bouterfas et al. 2018). The plant contains several

flavonoids, diterpenoids and a small amount of an essential oil (Sahpaz et al. 2002) that give the plant

antimicrobial, anti-inflammatory, and analgesic (pain-relief) properties. Horehound is also reported to

have many other biological activities that can benefit human health, including hypoglycemic, antidiabetic,

fungicidal, and antioxidant (Said-Al Ahl et al. 2015).

83. In recent years, due to the emergence of antibiotic resistance, the interest in biologically active

compounds isolated from plants has increased. Research on Lamiaceae species, and more specifically

Marrubium vulgare, is pursued to verify their ethnopharmacology1 capabilities.

84. In the United States, the herbal dietary supplement market which has been constantly growing since

2000, was worth more than seven billion dollars in 2016, and horehound was the number one selling

1 the scientific study of substances used medicinally, especially folk remedies, by different ethnic or cultural groups

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August 2018

herbal supplement for the fourth consecutive year. Horehound supplements sales exceeded US$125 m

in 2016 with an increase of 9.3% from 2015 (Smith et al. 2017). In New Zealand, the industrial sector for

natural health products is also growing and has almost doubled between 2004 ($ 400 m) and 2007 ($

760 m), with 80% of products exported to Australia, North America and parts of Asia (World Health

Organization 2013).

85. There is no quantitative information available on the weight of horehound herbage in the New Zealand

market. Dry leaves or herbal tinctures are sold by many herbalists. In her assessment, Dr Groenteman

of Manaaki Whenua-Landcare Research, estimated that 100g of herb costs approximately $12. If on

average 200g of herb is harvested from a healthy plant and there are two plants per square foot, one

hectare could produce 43,055 kg of herb with a potential revenue of $5,166,672 per ha (Groenteman et

al. 2017).

86. Morag McCay notes in her submission that horehound found in Central Otago is a key ingredient for

current and new Artemis Brands products and of better quality compared to other sources of plants in

the world.

87. Despite all the potential applications of the plant, large-scale cultivation of horehound remains

hypothetical. A business case by the medical herbal industry would need to be developed to garner

understanding of the prospects of cultivating horehound to supplement horehound herbage for medicinal

purposes in New Zealand.

88. We conclude that growing horehound could represent a moderate source of revenue for farmers in the

future given the capacity of New Zealand industry to cultivate horehound commercially is unknown at

this time.

Economic benefits of the two biocontrol agents

89. The applicant identifies the following economic benefits of the release of the plume moth and the

clearwing moth in New Zealand:

Reduced invasion or reinvasion of productive land.

Reduced production losses in the primary sector and improvement in the productivity of pastures and

lucerne on dry hill and high-country farms, especially in the South Island.

Reduced damage to wool from matting with horehound burrs.

Reduced control costs for territorial authorities, regional councils, DOC, land occupiers and other entities

that manage land.

90. In our assessment we consider whether the reduction of horehound would reduce the costs associated

with herbicide application, increase pasture productivity and increase the value of wool.

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August 2018

Biocontrol of horehound is likely to reduce the cost of herbicides

Table 5: Estimation of the costs to control horehound extracted from submissions received during

public consultation.

Localisation (region) Cost to control horehound

Amberley (Canterbury) Approximately $30,000 of additional contractor spraying cost on top of an

extra 800/h of labour.

Lake Tekapo (Canterbury) Around $7,000 on control which does not include the more frequent renewal of

the legume pastures.

Cheviot (Canterbury) $1,719 of spray cost for 18 ha infested by horehound.

Alexandra (Central Otago) Spray cost estimate $3000 to $5000 per year for medium scale grower of

lucerne.

Garston (Southland) $10,000 spent on a new machine to control horehound. Potential cost

estimated at $10,000 in labour and chemicals for 600 ha of lucerne and a

potential reduction of the gross farm income by 1/3.

91. There are no quantitative data available on the abundance of horehound in New Zealand. However,

observations made following a survey by the Horehound Biocontrol Group in 2016 estimated that the

population size of horehound doubles every three years. As the weed spreads, more herbicides are

sprayed for control and costs for farmers increase. For examples of costs to farmers see Table 5. In the

long term, with an integrated weed management strategy, biocontrol agents would help reduce the

abundance of the weed and its spread, reducing the application of herbicides.

92. We assess the release of horehound biocontrol agents to be likely to reduce the use of herbicides and,

therefore, the costs to control horehound in pasture and other productive habitats. Farmers would still

need to control other weeds using herbicides and where other weeds replace horehound in the future.

We conclude that the economic benefits from reductions in herbicide-related costs are minor.

Biocontrol is highly likely to increase pasture productivity

93. In many submissions we received, farmers note that the weed is adversely affecting their productivity.

The introduction of the biocontrol agents will help reduce infestations of horehound in pastoral areas,

leaving more areas for legume crops, e.g. lucerne, to grow. As a result there will be more legume crops

available to livestock.

94. We consider that biocontrol agents are highly likely to reduce horehound populations and therefore

increase pasture productivity and the magnitude of beneficial economic effects would be major.

Although horehound may still be limited in pastoral areas in New Zealand, its range in pastures will

continue to increase in the absence of sustainable control methods, such as biocontrol.

Biocontrol of horehound is highly likely to increase wool value

95. Due to the presence of burrs in sheep fleeces, the wool needs to be shipped to Australia for additional

cleaning. This extra step in the process is estimated to double the cost of wool (Groenteman et al.

2017).

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August 2018

96. The Hurunui Adverse Events Committee has estimated that, for an average size wool clip, the increased

cost of the wool process is between $2,000 to $7,500 per shearing. Peter Barrett, a farmer in Central

Otago, estimates that if nothing is done to control the weed it could cost him half of his annual wool

income.

97. We consider that the control of horehound in pastures by using the two biocontrol agents is highly likely

to reduce the processing costs that are attributed to cleaning the wool of horehound burr contamination

allowing farmers to make more revenue from wool sales. We conclude the economic benefits to sheep

farmers to be major.

Conclusion to the potential economic benefits of biological control

98. We considered the potential economic benefits that may occur following the release of the biocontrol

agents in New Zealand and found that it is likely that the cost of herbicide control and highly likely the

cost of wool processing would decrease. Further, we consider it highly likely that control of horehound

by the two moths would increase pastoral productivity. We note that future beneficial effects range from

minor to major for farmers where horehound is successfully suppressed by the biocontrol agents

minimising the weed’s impact in existing and newly invaded productive habitats.

99. We conclude the economic benefits of the introduction of the biocontrol agents to range from low to

high.

Assessment of risks

100. We have assessed all the risks but only discuss the effects that we considered to be significant. Effects,

where the magnitude of the effect and likelihood of that effect occurring is improbable or speculative, are

not included in our risk assessment. We considered the risks in the absence of introduction of the

biocontrol agents first followed by an assessment of the risks if they are approved for release.

Our assessment of the potential environmental risks

101. The adverse effects of horehound on the environment are discussed in paragraphs 15 to 21 of this

report.

Environmental risks of horehound in the absence of the biocontrol agents

102. We consider that the increase in horehound infestations on pastoral land would require more herbicide

applications and its spread to unmanaged habitats may adversely impact biodiversity. By not releasing

the two biocontrol agents, any potential direct or indirect adverse effects on the environment from the

moths are prevented.

Risks of using more herbicides

103. In the absence of the moths, other control methods, such as herbicides, are available to limit the impact

of horehound populations (see sections 31 to 38). However, these controls have not proven to be

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August 2018

efficient to reduce populations as the plant is still shown to be spreading (Groenteman et al. 2017). In

the submissions we received, D. A. Young, a farmer in Central Otago, qualifies horehound as the worst

weed on his property. Despite the use of mechanical and chemical controls to limit the spread of

horehound, a number of farmers report increases of the weed on their land.

104. In response to an increase in horehound infestation more herbicides will need to be sprayed, increasing

the contamination of soils and waterways, as well as soil erosion, and providing ideal conditions for

horehound to thrive and spread.

105. We note that more herbicides are highly likely to be used with an increase in horehound infestations.

Risks to decrease in biodiversity

106. Climate change is associated with more frequent extreme weather events with higher temperatures and

a change in rainfall patterns in New Zealand (Ministry for the Environment, 2018). These changes

impact ecosystems and could disadvantage some native plant species (Dukes & Mooney 1999). In

Australia, drier summers have proven to be beneficial to horehound which, despite being reduced like

other plant species during droughts, subsequently benefit from the lack of competition. As a

consequence, the population of horehound plants was found to exceed its pre-drought densities (Weiss

1996).

107. In unmanaged areas with greater biodiversity, the establishment of horehound may take over habitats

and constitute a barrier to endemic species (Ainsworth 1999). In New Zealand, horehound is found in

many parts of Otago and Canterbury regions where a high number of threatened taxa has been

identified (De Lange et al. 2004). Farmers noted in their submissions that tussock grasslands are also

contaminated by the weed. Horehound is not a competitive plant but can easily establish and invade

areas with sparse plants as well as areas with dense populations of mammals (Sagliocco & Coupland

1995).

108. According to Manaaki Whenua Landcare Research, there is no evidence of communities of insects living

in close association with horehound (see in the application, section 3.1.3). This low faunal association

supports the weedy characteristics horehound presents in New Zealand and Australia as it has no

natural predators here. Indeed, in Europe, the presence of many insect species associated with

horehound are essential to keep the population of horehound in check (Sagliocco 2000; Weiss et al.

2000) (Weiss & Sagliocco 1994).

109. We consider that the weedy characteristics of horehound are likely to have a moderate effect on plant

biodiversity, and a minor effect on the diversity of insects in unmanaged habitats.

Environmental risks of the two biocontrol agents

110. The applicant considers that the establishment of plume moth and the clearwing moth may have the

following potentially adverse effects on the environment:

Reduced native plant populations.

Interference of trophic webs.

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Facilitate the establishment of worse weeds.

Removal of M. vulgare from the environment undermines indigenous rights as well as national obligations

under the World Health Organization Traditional Medicine Strategy and the Convention on Biological

Diversity.

111. We consider that the release of the biocontrol agents may impact biodiversity by attacking non-target

plant species, adversely affect food webs and encourage the growth of other (possibly worse) weeds.

112. In relation to the status of the plant, we did not find information or received any submissions suggesting

that horehound is used for cultural and traditional purposes by Māori, therefore, it is not considered a

taonga species.

Biocontrol agents could attack non-target species

113. Biological control appears to be the least damaging approach to manage invasive species when

compared to chemical control although the actions of the biocontrol agents could also negatively affect

native or valued exotic flora and fauna. The potential for the two moths to have non-target effects must

be carefully considered to limit the risk (Baker 2002; Louda et al. 2003). The phylogenetic relationship

between the target plant and other plants in its introduced range needs to be determined to identify test

species for host range experiments (Wapshere 1974).

114. We note that host range tests for the two moths were conducted in Australia with species that are

specific to Australian flora and other plants to meet the requirements of the Australian regulatory system.

The tests included a number of plants taxonomically related to horehound (Marrubium vulgare) as well

as plants of economic importance (including culinary herbs and fruit plants). Further, we note that the

two biocontrol agents were introduced more than 20 years ago in Australia and no adverse effects on

non-target plants have been reported. No host range experiments were performed in New Zealand or

specifically on New Zealand native species.

115. In New Zealand, five native species of plants have been identified in the family Lamiaceae. Among

them, four are endemic species (Breitwieser et al. 2010-2018). The non-endemic plant species, also

present in Australia, was included in the host range test. Whilst the four endemic species were not

tested, species in the same genus were tested as they were identified as good surrogate species for the

New Zealand species.

116. Host-specificity studies were performed to identify the potential plant species that could be at risk from

the introduction of the plume moth and the clearwing moth (Sagliocco & Coupland 1995).

117. The plume moth is described as host specific with larvae feeding only on three Marrubium species:

white horehound (M. vulgare), scallop shell (M. supinum) and black horehound (Ballota nigra). During

the test, five larvae were placed on growing shoots of twenty-five plants species in five Labiatae sub-

family and 22 other families. The test was replicated eight times for each test plant. The results show

that the plume moth only attacks plants in the same sub-family as M. vulgare, and do not feed on other

species, confirming the high host-specificity of the moth (Victorian Department of Conservation and

Natural Resources 1993).

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August 2018

118. The clearwing moth was tested on twenty-four plant species in five Labiatae sub-families and 19 other

families. At least five larvae were placed on each test plant. The experiment was replicated four to six

times according to the availability of the plants. The presence of larvae was recorded after two to three

weeks. The results show that larvae survived on four of the seven species in the genus Marrubium, and

one species in the genus Stachys. However, the survival rate decreases rapidly where the species are

more distantly related to M. vulgare.

119. Only one species in the same tribe as M. vulgare, and six species in the genus Stachys, can be found in

New Zealand and are potentially at risk from the introduction of the clearwing moth. However, we note

that all of these species are exotic plants, with no commercial interests. Bailey mentions that the genus

Sideritis is also targeted by the plume moth (Bailey 2007) but only two species in this genus are found in

New Zealand and both are not native.

120. Based on the information available, there are no native species closely related to horehound (M.

vulgare) that would be at risk from the introduction of the two biocontrol agents. We conclude that it is

highly improbable that the plume moth and the clearwing moth would attack non-target native plant

species. We consider that if off-target attacks should occur it would be incidental and would cause

minimal effects.

Biocontrol agents could affect food webs and insect interactions

121. The fauna community associated with horehound has not been studied well in New Zealand. However, a

partial survey revealed poor fauna association with horehound in Australia and New Zealand compared

to Europe where large herbivorous insect communities and numerous pathogens are present on

horehound (Weiss & Sagliocco 1994). Therefore, the introduction of the biocontrol agents and

concomitant effects on horehound abundance are very unlikely to disturb horehound-fauna

associations. Horehound would also not be eliminated by the two agents; the effects on the plant would

be gradual at first and dependent on population densities of the two moths at specific sites. Their actions

would have minimal effects on fauna communities found on horehound.

122. Horehound flowers could be used as a source of food in spring/early summer for honey bees but the

weed became only recently wide spread. We consider that bees have access to various other plants.

For example, in pastoral areas infested by the weed, horehound flowers are replaced by lucerne flowers,

a great source of food for bees (Delaplane et al. 2000). Therefore, the decrease of horehound would not

adversely affect bees.

123. In a study of biocontrol agents of Lepidoptera in Europe they found one parasitic insect on plume moth,

identified as Cotesia spp.(Victorian Department of Conservation and Natural Resources 1993). In New

Zealand, there are five species of Cotesia known (C. urabae, C. ruficrus, C. kazak, C. rubecula and C.

glomerata) all of which have been introduced as biological control of various pests (Popay 2008)

(Burgess 1987; Harvey et al. 1999; Cameron & Walker 2002; Cameron et al. 2006; Berndt & Allen

2010). The majority of these Cotesia species appear to be host specific. However, species like C. kazak

can be found in similar habitats (vegetable crops like lucerne) and may target the larvae of the plume

moth and the clearwing moth. Despite the uncertainty around the potential for the Cotesia parasitoids to

attack the two moths as well as other Lepidoptera species that may use horehound vegetation for

shelter (via apparent competition), we consider that the impact on populations of other moths would be

minimal as horehound is not a known host to native moths in New Zealand.

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August 2018

Horehound could be replaced by worse weeds

124. The decrease of horehound could provide more space for worse weeds to grow (Edwards 1974). Native

plant species or crops will need to be sown to limit the comeback of horehound or the spread of other

weeds that thrive in similar disturbed habitats like broom (Cytisus scoparius) (Syrett 1996). The new

infestation of unmanaged habitats where the biocontrol agents have established will be slow allowing

native and invasive species to compete with horehound.

125. Although we consider that it is likely that horehound could be replaced by other weeds in pastoral

areas, this could be managed effectively by farmers. In unmodified areas that are remote, human

intervention could be needed to limit the infestation of other weeds where horehound is controlled by the

two biocontrol agents, however, this would be site specific and a variety of factors would play a role,

including existing vegetation at the site and quality of soil.

Conclusion on the potential environmental risks of biological control of horehound

126. We considered the potential environmental risks that may occur following the release of the biocontrol

agents in New Zealand and found that it is very unlikely that food webs will be disturbed where the

agents will operate in and around horehound populations and highly improbable for either the plume

moth or clearwing moth to attack non-target plants. We estimate the magnitude of the risks to be

minimal since the moths are unlikely to attack non-target species and the horehound fauna community

is poor.

127. We consider the adverse environmental effects from the introduction of the two biocontrol agents in New

Zealand’s environment to be negligible.

Our assessment of the potential economic risks

128. The applicant considers that the establishment of the plume moth and the clearwing moth may have the

following potential adverse effects on the market economy:

Impact on native plant populations and on medicinal/culinary herbs in the family Lamiaceae once

populations of the target host had declined.

Accessibility to wild-crafted M. vulgare will be reduced due to the irreversible nature of biocontrol.

The presence of medicinally valued plants on a farming property should be viewed as an additional

source of income to the farmer, targeting other weeds would make better use of resources.

Economic risks of horehound in the absence of the biocontrol agents

129. We consider that horehound infestation will result in the use of more herbicides in pastoral areas, the

reduction of pastures available for livestock and the increase in the treatment costs of wool.

Risks of the increase in the cost of herbicides

130. With the increase of horehound populations, farmers will need more herbicides to control the weed. On

average farmers spend $55 per ha on chemical products (Groenteman et al. 2017) and despite

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August 2018

achieving good short-term results, the weed rapidly re-establishes from its seed bank (Ainsworth 1999).

Furthermore, chemicals affect other plants species and decrease soil quality in the long term providing

more land with ideal conditions for horehound seed to grow.

131. We note it is highly likely that the cost of herbicide application to control horehound will increase with

the spread of horehound.

Risks of the increase in the cost of crops

132. Herbicides cause damage to non-target plants and kill on average 40% of lucerne. The reduction in

pasture plants could add an extra cost to farmers who would need to replace the loss. Indeed, lucerne

will need to be sown every five years instead of every 12 to 13 years, with a crop replacement cost of

$550 per hectare (Groenteman et al. 2017). Daniel Maxwell reports in his submission that lucerne will

not last more than two years compared to the standard 10 years normal life-expectancy in the absence

of weed management and cost a total of $723 per ha.

133. We note it is highly likely that the cost of pastoral crops will rise due to the increase in herbicide and

labour use to control horehound.

Risks of reducing productivity

134. Horehound infestations replace crops sown by farmers in pastoral areas. The replacement of highly

nutritive monoculture legumes like lucerne by unpalatable leaves of horehound reduces the amount of

food available for livestock. This lack of food available could increase the time for livestock to reach their

slaughter weight, affecting farm productivity and profitability (Baker 2002; Blackwell et al. 2011).

135. We note that it is highly likely that the expansion of the weed will reduce access to healthy palatable

food for livestock.

Risks to decrease wool value

136. The proliferation of horehound will increase contamination of wool by burrs and reduce the value of the

fleece. Thirty years ago, in Australia, the cost of wool treatment, without including the loss of pasture

land and the loss of income from contaminated meat, was estimated at A$680,000 (Sloane & King 1988;

Victorian Department of Conservation and Natural Resources 1993; Ainsworth 1999). In addition to this

cost, farmers in New Zealand have to add the cost of shipping and processing the wool in Australia.

137. The cost of the weed to New Zealand is not well documented. However, a survey by the Horehound

Biocontrol Group in August 2016 revealed invasion of horehound makes ‘high-country land un-economic

to farm’ (see section 93 to 95).

138. We note that it is highly likely that wool value will decrease with the increase in horehound infestations

in pasture areas.

Economic risks of the two biocontrol agents

139. We consider that the release of the biocontrol agents may impact the availability of herbage for

herbalists and other members of the public that may harvest the plant.

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The risk in the decrease in plant availability

140. The introduction of the biocontrol agents will help to reduce the populations of horehound but will need

to be used in correlation with other control methods like herbicides and physical control to be highly

efficient. In unmanaged habitats the only potential control will be the presence of the moths, which do

not destroy the plant but reduce its dispersal, therefore herbalists would be able to continue collecting

horehound leaves.

141. In addition, the dispersal of biocontrol agents is a long term process. Clarke notes that the plume moth

spread rate is dependent on rainfall. Areas receiving more than 400 mm rainfall per year facilitate the

spread of the moth by providing more food (Clarke et al. 2000). The spreading of plume moth is

estimated to be between 800 m and 1 km per year but any interruption in the horehound infestations

could be a barrier to its dispersal (Clarke et al. 2000; Ireson et al. 2000).

142. Management of areas where horehound is cultivated could be a solution to keep a viable population

isolated from pastures. Organic herbicides or natural enemies of larvae like chicken could be used to

keep the two biocontrol agents at bay (Bauer et al. 2017).

143. Another approach would be to integrate the harvest of horehound in farm weed management strategies

by giving access to infested pastures before the production of seeds and the spray of herbicides.

Herbalists will be able to collect herbage and help maintain a low population.

144. We consider that it is very unlikely that the reduction of horehound population will affect the harvest of

herbs, and thus adversely impacting the businesses of medical herbalists in New Zealand. Further, there

are other plants or natural remedies that hold identical or similar properties that are already available

commercially.

Conclusion to the potential economic risk of biological control of horehound

145. We considered the potential economic risks that may occur following the release of the biocontrol agents

in New Zealand and found that it is very unlikely that herbalists and their business interests would be

adversely affected by the release of the two agents. The penetration of the two agents into natural or

unmanaged habitats is expected to be slow and effects of the two agents in pastoral areas could be

managed to reduce effects on horehound populations earmarked for harvesting. The magnitude of the

economic risks for herbalists is considered to be minor.

146. We consider the adverse effects of the introduction of the two biocontrol agents to New Zealand’s

market economy to be negligible

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August 2018

Conclusion on benefits and risk assessment

147. After completing our risk assessment and reviewing the available information, we consider that the

adverse effects of releasing the plume moth and the clearwing moth to control horehound are negligible

and the benefits are significant (Table 6). Therefore, our assessment found that the benefits from the

release of the two agents outweigh the risks.

Table 6: Summary of our assessment of the benefits, risks and costs associated with the release of the

plume moth and the clearwing moth to control horehound.

Potential outcomes Likelihood Consequence Conclusion

Potential beneficial effects to the environment

Limit the invasion of new sites, especially

conservation and sensitive areas

Highly likely Major High

Reduce the use of herbicides Likely Minor Low

Increase in biodiversity in managed /

unmanaged habitats

Likely Minor / major Low / medium

Potential beneficial effects to the market economy

Reduce cost to control horehound from

herbicides

Likely Minor Low

Increase in pasture productivity Highly likely Major High

Increase in the value of wool Highly likely Major High

Potential adverse effects on the environment

Risks to non-target species Highly improbable Minimal Negligible

Risk to ecosystem interactions and food

webs (indirect effects)

Very unlikely Minimal Negligible

Potential adverse effects to the market economy

Decrease plant availability for medical

herbalists and their businesses

Very unlikely Minor Negligible

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August 2018

Relationship of Māori to the environment

Kaupāpa Kura Taiao cultural assessment

148. The potential effects on the relationship of Māori to the environment have been assessed in accordance

with section 5(b), 6(d) and 8 of the Act. Under these sections, all persons exercising functions, powers

and duties under this Act shall take into account the relationship of Māori and their culture and traditions

with their ancestral lands, water, sites, waahi tapu, valued flora and fauna and other taonga, and the

Treaty of Waitangi.

149. Findings of the cultural risk assessment (CRA) for the plume moth and the clearwing moth in relation to

the above HSNO provisions are summarised below. A full CRA can be found in Appendix 2 of this

report.

150. Based on the information provided, the benefits of the proposal to introduce the horehound plume moth

and the horehound clearwing moth appear to outweigh its disbenefits. The potential risks to Māori

interests may be acceptable but information gaps remain.

Section 5(b) – recognise and provide for cultural well-being

151. Based on the available information, it does not appear that the proposal will put the cultural well-being of

Māori at risk or infringe on Māori cultural beliefs and environmental frameworks. It may be that further

information is needed to test this statement.

Section 6(d) – take into account Māori relationship to the environment

152. The EPA’s cultural risk assessment considers potential risks and impacts on Māori interests including

the relationship of Māori to the environment, culturally significant species and resources, and tikanga

(customary values and practices) associated with these taonga. It has identified some uncertainties

around potential impacts on culturally significant species and wider ecosystem effects. Concerns around

these issues can be addressed by obtaining with further information and evidence. These matters aside,

the application is not inconsistent with Māori cultural beliefs and environmental frameworks.

Section 8 – take into account Treaty of Waitangi principles

153. The active protection principle i.e. the Crown has a duty to actively protect Māori interests. The EPA

has undertaken a cultural risk assessment to consider potential risks and impacts on Māori interests. As

noted above, the concerns in relation to culturally significant species and wider ecosystem effects can

be addressed by obtaining further information and evidence.

154. The informed decision making principle i.e. the Crown has a duty to make informed decisions. The EPA

has undertaken a cultural risk assessment to ensure decision making on this application is informed by a

Māori perspective. No feedback has been received from Māori groups regarding the proposal.

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August 2018

155. The taonga principle i.e. ‘taonga’ include all valued resources and intangible cultural assets. The scope

of the EPA’s cultural risk assessment includes tangible and intangible taonga, such as culturally

significant species and resources, and the tikanga (customary values and practices) associated with

these taonga.

Summary of the applicant’s engagement with Māori

156. The applicant took into consideration some key Māori cultural principles that apply to biological control

proposals in general identified by the Māori Reference Group1 (MRG) in 2015. The applicant engaged

with Māori via consultation with members of Te Herenga2, iwi and Treaty settlement authorities in the

South Island, the Ngāpuhi HSNO komiti and the Ngāi Tahu HSNO komiti.

157. As part of this assessment a cultural risk assessment was done by the EPA Māori team Kaupāpa Kura

Taiao.

Consideration of the Māori Reference Group

158. The MRG was established to facilitate consultation with Māori interests that may be impacted by the

release of new weed biocontrol agents. The MRG noted that they will not comment on every application

for a new pest control agent but consider the principle level impacts of new biocontrol agents and

provide guidance that should be covered in individual applications.

159. The MRG noted that the broad cultural principles that apply to considerations on the introduction of new

biological control agents, pest management and environmental protection are Kaitiakitanga3 and

Manaakitanga4. The MRG considered that new biocontrol agents pose the potential to both have a

positive impact by aiding in the restoration of balance and reduction in environmental degradation, and a

negative impact by leading to further disturbance.

160. The applicant did not identify costs or benefits exclusive to Māori as horehound does not seem to have

encroached any taonga species and the host-range of the biocontrol agents does not include native

plants (see section 53 to 93). Furthermore, the number of insects collected around horehound is low and

therefore, the impact of the moths will be minimal.

Consultation with Te Herenga

161. Members of Te Herenga were given information on the biocontrol agents propose to control horehound

in May 2017. No feedback has been received.

1 The MRG was made up of four members with expertise and experience relevant to biological control applications.

2 Te Herenga is made up of Māori resource and environmental managers, practitioners, or experts who represent their iwi, hapū, or Māori

organisation on matters of relevance to the activities and decision making of the EPA.

3 The responsibility of Māori to manage the natural resources within and beyond their hapū and iwi boundaries for the benefit of future

generations.

4 The ability of iwi, hapū or whanau to ‘manaaki’ (support and provide for) their people and visitors, which is central to the maintenance

and enhancement of ‘mana’. It is noted as a key cultural principle and practice, and extends to physical, spiritual and economic

wellbeing.

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August 2018

Regional consultation

162. Horehound is mainly found in the South Island therefore, information was provided to the HSNO komiti

of Ngāi Tahu, Ngāpuhi HSNO komiti, and eight iwi and hapū of Te Tau Ihu. No response has been

received.

Minimum Standards

163. Prior to approving the release of new organisms, the EPA is required to determine whether the plume

moth and the clearwing moth meet the minimum standards set out in section 36 of the HSNO Act.

Can plume moth and clearwing moth cause any significant displacement of any native species within its natural habitat?

164. The applicant provided information from host range testing conducted in Australia showing that the two

candidate biocontrol agents are specific to the tribe Marrubieae with the exception of Stachys arvensis

for the clearwing moth. We note that there are no native species belonging to the tribe Marrubieae or the

genus Stachys in New Zealand.

165. Similarly, studies in the native range of the plume moth (W. spilodactylus) and the clearwing moth (C.

mysiniformis) show that there is no native moth in the same genus in New Zealand. However, we note

that there is some uncertainty around the taxonomic classification of a potential synonym Pterophorus

spilodactylus for the plume moth. At least three other known native species in this genus are present in

New Zealand (Pterophorus monospilalis, P. innotatalis, P. furcatalis) (Dugdale 1988; Patrick 1992;

Lyford 1994). There is very little information available on these native species and only P. monospilatis

have been found in a disturbed environment (Patrick 1992) similar to where horehound can be found. As

the information regarding taxonomic synonymy could not be confirmed we decided not to include the

synonym in our assessment of the effects of the introduction of the plume moth might have on native

moths in their natural habitats.

166. We consider it unlikely for the plume moth and the clearwing moth to have any adverse effects on native

plant species in our environment. The adverse indirect effects on ecosystem interactions, such as food

webs, that could occur following the introduction of the plume moth and the clearwing moth are

discussed in paragraphs 110 to 127. We concluded that it is very unlikely that the two agents would

cause excessive pressure on native insect species through interactions such as apparent competition

and cross-breeding in New Zealand.

167. The action by the two agents would gradually cause decline in horehound infestations. Invertebrates

found on horehound plants in Australia (Weiss & Sagliocco 1994) and in New Zealand as the results of a

survey (see application form section 3.1.3) showed low diversity in the numbers of species using the

plant for shelter rather than as a host.

168. We do not expect the two moths to cause any significant displacement of any native species within its

natural habitat.

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August 2018

Can plume moth and clearwing moth cause any significant deterioration of natural habitats?

169. The two biocontrol agents are host-specific and there is no native species in the same Marrubium genus

in New Zealand.

170. The two agents would not cause rapid decline in horehound abundance in natural habitats. We expect

effects to be gradual at first and, as a result would not cause any significant deterioration of natural

habitats.

Can plume moth and clearwing moth cause any significant adverse effects on human health and safety?

171. There are no mechanisms of interactions between humans and the two candidate agents that may

cause adverse effects to human health and safety.

Can plume moth and clearwing moth cause any significant adverse effect to New Zealand’s inherent genetic diversity?

172. There are no native Wheeleria or Chamaesphecia moths present in New Zealand, therefore, it is unlikely

that the two candidate agents could cross-breed with native species thereby adversely affecting New

Zealand’s inherent genetic diversity.

Can plume moth and clearwing moth cause disease, be parasitic, or become a vector for human, animal or plant disease?

173. The plume moth and clearwing moth are not known to cause disease or become a vector for animal,

plant or human disease in their native range.

Conclusion on the minimum standards

174. We consider that the plume moth and clearwing moth meet the minimum standards as stated in the

HSNO Act.

Additional matters to be considered

175. Section 37 of the Act requires EPA staff to have regard to the ability of the organisms to establish

undesirable self-sustaining populations and the ease with which the organisms could be eradicated if

they established such a population.

176. We note that the purpose of the application is to release the plume moth and the clearwing moth and to

allow the organisms to establish and develop self-sustaining populations and disperse to attack its host,

horehound, in our environment. This is the foundation of a classical biological control strategy and

therefore we consider that any population of plume moth and clearwing moth will not be undesirable.

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August 2018

Recommendation

177. Our assessment has found that the benefits of releasing Chamaesphecia mysiniformis and Wheeleria

spilodactylus outweigh any identified risks or costs. We, therefore, recommend that the application be

approved.

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August 2018

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August 2018

Appendix 1: Summary of submissions

# Submitter Support/A

gainst

Summary of the submission

127156 Bruce Jolly Support Horehound has a significant and increasing economic impact on my farming enterprise. Wool contamination. Increase density

around the station (roads, tracks and stock droving routes). Infestations are mostly on terrain not suitable for cultivation but

covers native grass, tussock with high biodiversity. The property is 3200 ha, 800 ha at high risk to be contaminated by

horehound but with no grazing value (steep), and 400 ha already colonised with 80 ha fenced off and no longer available for

sheep grazing.

127159 Rob Simons,

Marlborough District

Council

Support Horehound is not a pest plant in the Marlborough Region. Chemicals are expensive and often ineffective. Spread will threaten

pastoral production.

127160 Morag McCay, Artemis

Brands

Against Otago is a key area for harvesting medicinal plants for Artemis. We do not wish to see horehound completely removed from all

areas or made inaccessible. We have seen the impact of biocontrol agent on St John's Wort with the reduction of the plant

availability. Respiratory illness in NZ and antibiotic resistance are increasing. Horehound is an alternative to synthetic

medicines. We risk losing the potential for a new and thriving business. Farmers could diversify their activity due to the effects

of climatic changes on their businesses

127161 Shane Philips Support Horehound disperses by sheep and covers areas only accessible by aerial spraying. We have not been approached for

medical harvesting. Horehound increases our costs in unproductive land, shearing, wool sorting and spraying.

127284 Ian & Jess Knowles Support Dry conditions strongly favour the aggressive spread of horehound. The huge increase in horehound has resulted in

approximately $30,000 of additional contractor spraying costs on top of approximately 800 hours grubbing and spot spraying.

Chemical spraying has resulted in the total loss of 45 ha of pastures, leaving poorly performing pastures. Huge financial costs

to cultivation, seeding and fertiliser use and also in reducing our pasture quantity and quality. Horehound burrs greatly reduce

wool clip value. Horehound is our biggest weed challenge.

127285 Carl Forrester Support Becoming a very expensive weed to control and severely discounts the price of wool.

127288 Tim Davis Support Increase in horehound over the last 10 years especially on sunny faces of hills. Burrs greatly reduce the value of Merino wool

(priced up to $100 per kg). Chemicals are against our marketing of sustainable product.

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127302 Digby Heard Support Cost getting out of control and move to natural ways would be a huge help.

127303 Warwick Lissaman and

Malcolm Taylor

Support Horehound establishes easily in disturbed sites and displaces desirable forage. Burrs devalue the wool and cause distress in

lambs. The weed is exceptionally hard to control, reducing productivity. There are anecdotal reports of stand life reduction of

30% or more. A recent survey estimated the cost of horehound to dryland farming in New Zealand at $6.85 million per annum:

• One or two plants per ha can spread to multiple paddocks within one year from grazing rotations.

• Biocontrol minimises plant populations but the seed bank, that will continue to be a problem for many years, will allow the

biocontrol agent to establish and maintain itself.

127304 Herstall Ulrich Support I do not want to use brush weed chemicals that leaves me with spot hand gun spraying or grubbing which are labour intensive.

Most problematic in lucerne.

127305 Dawn and David

Sangster

Support We noticed that the horehound population is growing and spreading. Spraying also affects lucerne and horehound is back 3

years later. Burrs devalue the wool and affect young lambs. Burrs present in mohair fleece renders it non-valuable.

127306 Bill Bayfield, Environment

Canterbury

Support Horehound is a widespread weed in dry hills and high-country of Canterbury and a problem in lucerne and open pastureland. It

reduces wool value. Planting lucerne is a common practice and herbicides are too damaging.

127307 Pat Garden Support The lucerne plant is not tolerant to chemicals, spot spraying is the only option but the rapid expansion of the weed makes it

totally uneconomic. Spraying results in a spell for two years before re-sowing. Lucerne needs to be replaced more often, every

7 years instead of 10. Annual maintenance costs of a lucerne stand increases. Horehound lowers the dry matter yield,

increases chemical application, shortens the stand life of crops and contaminates wool. A reduction of vigour through biocontrol

would greatly assist in its management.

127310 Rod Hitchmough, DoC Support With its very narrow host specificity and success as biocontrol agents in Australia, we agree that the likelihood of non-target

impacts is extremely low and would benefit conservation as well as agricultural activities. We note that there is too much

reliance on overseas information and too little testing of potential New Zealand hosts and we do not support this general

approach.

127311 Will and Emily Murray Support Invasion of native tussock and lucerne is getting worse. Also a major threat for our merino wool quality. We are spending

around $7000 pa on control and have to renew our legume based pastures every 5 years.

127312 John Gardner Support Bigger cost in wool process and control. It also smothers out the lucerne and pasture. Lucerne is vital for farming in dry areas

and has increased benefit, approximately 25% in gross income.

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August 2018

127313 Daniel Maxwell, Hurunui

Adverse Events

Committee

Support Canterbury is prone to drought which has a significant financial impact on farmers. Lots of dormant seeds wait for the right

conditions to emerge. Current options, grubbing and spraying, are inefficient and each cost $70/ha annually. Extensive and

expensive spray treatments were not conclusive. The increase in the costs to process wool is $2000 to $7500 per shearing. In

2016, spraying horehound out of stock camps and permanent pasture cost $1,719 plus GST for 18 ha, therefore $95.50 per ha.

Lucerne life-expectancy goes from 10 to 2 years.

127314 Jerry Hurst Support Horehound has become our biggest problem in the last 5 years. It infests lucerne and some young pasture paddocks. Spraying

and re-drilling lucerne are the major cost. It devalues wool and certain paddocks infested are closed for grazing when the weed

is in seed.

127315 John Murray Support Horehound is an increasing problem. We find more and more in uncultivated tussock grasslands. Herbicides kill non-target

species. Spot spraying is not working due to its extensive nature and inaccessibility. Horehound displaces indigenous

vegetation and decreases productivity. Hard grazing is not a viable option as it impacts biodiversity and requires sub-divisional

fencing (expensive and hard to get resource consent). Horehound won't go extinct because of the two biocontrol agents and

will still be available to anyone who wishes to use it. If horehound infestation increases, the cost of early replacement of lucerne

and spot spraying will be in the tens of thousands of dollars.

127316 Gordon and Spin Lucas Support Major problem in our lucerne paddocks and sunny faces of our hill country. Too invasive to spot spray. Affects wool quality.

127317 David Black Support Horehound grows prolifically in our region (Parnassus). Our farm relies on lucerne, clover and chicory for their resistance to

harsh climatic conditions. Herbicides and ploughing are the only options to control horehound but it is expensive and

unsustainable. Horehound could be easily cultured and/or grown in controlled conditions for herbalists and the biocontrol agent

won't lead to the end of the plant. We have 300 ha of lucerne, 150+ ha chicory and red clover and 5,000 ha of pasture with

10% contaminated by horehound. Biocontrol represents a huge opportunity to improve the sustainability and viability of our

farm and indeed the entire New Zealand pastoral sector.

127318 Davor Bejakovich,

Greater Wellington

Regional Council

Support Horehound displaces desirable foliage and is extremely hard to control without causing adverse impacts on valuable crops.

Burrs devalue the wool. The weed is widespread in the Wellington Region. Climate change will provide favourable conditions

for horehound. Conventional methods of control (herbicides and manual) are often unsuccessful and uneconomic. Biocontrol is

the only effective long term management option. In the absence of control, testing and management need to be thorough prior

to release. Biocontrol agents will reduce the reliance on manual removal and the use of herbicides.

127319 Kataraina O’Brien, Bay of

Plenty Regional Council

Support We support the biological control of this weed as this will reduce the current distribution and potential future spread of

horehound.

39


August 2018

127326 David Ensor Support Horehound is a serious threat to our farming operation. The weed is increasing and has a complete cover on some sheep

camps. These areas cannot be used for grazing at certain times of the year to avoid wool contamination. We used to have 100

ha of lucerne but it has been reduced to 15 ha due to horehound.

127330 Warren Hanley, Otago

Regional Council

Support There is significant presence of horehound in the drier central areas of Otago.

127331 Glenn Tomlinson Support Our 35ha of lucerne is reduced due to the infestation of horehound. We do not spray and our only option is grubbing by hand

which is labour intensive and time consuming. The weed decreases wool value. If we cannot control horehound we will need to

use more herbicides and re-grass paddocks with different crops which may not be as adapted to dry conditions.

127332 Lyndon and Millie

Mattews, Puketira deer

Support Climatic conditions have led to an explosion of horehound (dry summers and wet autumns). Grubbing not an economically

viable control anymore. Lucerne has improved the productivity and profitability on our dryland pastoral farming system.

Spraying increases bare ground and risk of windblown soil erosion. We will try to smother seedling by sowing pasture mix.

127333 Marty Deans Support Chemicals are not specific to horehound and kill lucerne.

127334 Angela Johnston,

Federated Farmers of

New Zealand

Support Horehound is becoming a serious weed problem for farmers, it establishes quickly on disturbed ground, produces burrs that

devalue wool and cause animal welfare issues. Horehound reduces the productivity of the crop. The use of herbicides kill other

plants and leave an erosion prone bare ground favourable to the weed reestablishment. Horehound is allegedly valued as a

medicinal herb, but the New Zealand market size has not been provided by the horehound foraging community. Biocontrol

agents will not eliminate horehound and options to mitigate losses to herbalists are easy to implement.

127335 Nicola Chisholm, Beef

and Lamb New Zealand

Central Otago

Support Farmers are struggling to control horehound. Lucerne is particularly affected and productivity is reduced. Crops affected by

chemicals and manual grubbing is time consuming, expensive and not effective in the long-term. Costs for sprays alone are

estimated to be $3000 to 5000 per year for medium scale growers of lucerne. Horehound reduces wool quality and value.

127336 Guy & Jackie Simpson Support Horehound is taking over vast areas of productive farmland, competing with introduced clovers and grasses but also native

tussock. It makes paddocks less productive and decreases wool income. Current control methods are time consuming,

increase cost and not very effective. Some sprays may leave barren areas. Biocontrol will be more environmentally friendly.

40


August 2018

127337 D A Young Support Horehound is the worst weed on my property, invading lucerne, and sunny gullies and faces. Spraying kills everything and

sterilizes the soil for months. Horehound burrs downgrade the value of merino wool. Horehound reaches water deeper than

pasture species and makes sowing impossible. Large areas of inland Otago and Canterbury are invaded which destroys the

pasture.

127338 Geva Innes Support Horehound exploded since we started reseeding paddocks. Tried poisoning with very little effect and grabbing them out is only

temporary. Happy to try biocontrol agents if they do not affect other plant species

127339 Peter Barrett Support Horehound is more and more prevalent on our farm and the surrounding farms. We need an alternative to limit chemicals that

kill soil microorganisms and decrease organic matter. Our income could be reduced to half if the proliferation of horehound is

not stopped. Horehound seems to get tolerant to chemicals that only delay its proliferation whilst also impacting the

environment. Manually pulling disturbs the existing bed and increases germination. The loss in farm production and increase in

expenses are forcing us to sow rye corn only.

127340 Barry Wards, MPI Support MPI supports the application through the allocation of funding from the Sustainable Farming Fund. Horehound is spreading

rapidly, becoming a serious weed in many parts of New Zealand, especially in dryland lucerne pastures. Chemicals are not

efficient, killing lucerne crops and favouring the return of more weed plants. Biocontrol offer a long term cost-effective and

sustainable option. While the moths would have a beneficial effect on the environment, the farming industry and the

sustainability of some farming enterprises, they will also have an adverse effect on the medical use of horehound. MPI

recognises that the release of the two moth species is unlikely to eradicate nor eliminate all horehound from New Zealand.

127341 Julia Mackenzie,

Mackenzie Country Trust

Support Protect biodiversity hotspots in the unique Mackenzie intermontane basin and benefits to local farmers.

127342 Jamie McFadden, Rural

Advocacy Network

Support Horehound invading valued crop lucerne to an extent that farmers are questioning the viability of growing lucerne. Existing

control measures are struggling to effectively control horehound.

127343 Denis Fastier Support Helicopter spray not effective long term, horehound back after 2 or 3 years. Spraying is labour intensive and infestation so

extensive that effective control is no longer feasible.

41


August 2018

127344 Matthew Tayler Support Our conversion to lucerne triggered the infestation of horehound. In 2017 we spent approx. 12 h grubbing and applying

chemicals on 20 ha. In 2018, it was present on 50 ha and required 20 h of control work. We have purchased a weed wiper

($10,000) to apply targeted chemicals to horehound for the coming season as I anticipate at least 150 ha will need attention

and the first 50 ha infestation is becoming thicker. With potentially 600 ha of lucerne to control it will cost us $10,000 (labour +

chemicals) for a sparse infestation of one plant /100m². Old lucerne fields have now one plant per 40m² and my neighbour has

older fields with one plant per 5m². Controls not efficient and in the future it may reduce the gross farm income by one third.

Changing climate and more frequent drought will increase the infestation. Horehound for medicinal purposes can be grown in

isolated and confined areas.

127345 Carolyn Dundass Support Horehound is found on lower hill faces where the soil is bare and more recently in our paddocks. Grubbing not feasible on the

hill where the infestation is too dense to control. I do not want to spray as it is too damaging for other species.

42


August 2018

Appendix 2: Cultural Risk Assessment (CRA) for New Organisms

Application

Purpose of CRA

The purpose of this Cultural Risk Assessment (CRA) is to assess the potential risks and impacts on Māori interests

associated with releasing the horehound plume moth (Wheeleria spilodactylus) and the horehound clearwing moth

(Chamaesphecia mysiniformis) as biological control agents for the weed horehound (Marrubium vulgare). Cultural risk

includes any negative impacts to treasured flora and fauna species, the environment, and the general health and well-

being of individuals and the community.

Ngā here ture (Statutory obligations)

This CRA has been undertaken in accordance with sections 5(b), 6(d) and 8 of the Hazardous Substance and New

Organisms Act 1996 (HSNO) which oblige all persons exercising functions, powers, and duties under the HSNO to:

Recognise and provide for the maintenance and enhancement of people and communities to provide for their cultural well-being, and

Take into account the relationship of Māori and their culture and traditions with their ancestral lands, water, taonga and the principles of The Treaty of Waitangi (Te Tiriti o Waitangi).

The Treaty principles most relevant to assessing and deciding this application are:

The Crown has a duty to actively protect Māori interests.

The Crown has a duty to be informed and make informed decisions.

‘Taonga’ include all valued resources and intangible cultural assets.

Introduction

Horehound weed arrived with settlers in the middle of the 19th century and was recorded as naturalised in New Zealand

in 1867 before being classified, for the first time, in 1902 as a weed.

Under favourable conditions, the weed can quickly colonise newly disturbed areas and form dense monocultures. Its

efficient seed germination strategy and its adaptability to different environmental conditions are factors that support the

invasive tendencies of horehound on pastures areas in Australia and New Zealand.

Climate changes associated with drier summers, harsh climatic conditions that contribute to the decrease of other pasture

species and intense grazing by sheep on other species, due to the unpalatable taste of horehound, create ideal

conditions for horehound to grow and invade pastoral areas. The areas most impacted by the horehound weed are semi-

arid states, like north-western Victoria and south-eastern South Australia, and Otago and Canterbury in New Zealand.

In New Zealand, horehound has been observed in tussock grass where threatened and naturally uncommon species are

present.

43


August 2018

The increase of horehound in pastoral areas has a direct impact on livestock by reducing the amount of food available,

which increases the time required to reach slaughter weight spent grazing before being ready to go to the abattoir.

The presence of horehound also affects wool quality and increases the cost for farmers by adding steps to the cleaning

process to eliminate the burrs from the fleeces.

Spraying large areas infested by horehound helps manage infestations but this has a negative impact on the others

species. Furthermore, the use of herbicides increases the risk of erosion as soil becomes exposed to the elements

creating a favourable environment for the weed.

While a pest for farmers, horehound is considered a therapeutic plant. Its medical properties have been used for

centuries in traditional medicine to treat various diseases including inflammatory, gastroenteric and respiratory disorders.

Māori worldviews of insects, plants and biocontrols

Insects are culturally significant due to the part they play inkorero o mua (traditional narratives) and Māori environmental

lore. Kōrero o mua tell us that insects and other arthropods belong to a group within the domain of Tāne-mahuta (deity of

humans, forests and forest dwelling species) known to Māori as Te Aitanga Pepeke (insect relatives) and Te Tini o

Hakuturi (the multitude of bow-legged ones). The broad domain of Tāne is sometimes known as Te Marae o Tāne

(literally ‘the precinct of Tāne’), which can be interpreted loosely from a western point of view as being terrestrial

ecosystems. Te Aitanga Pepeke is a sub-group representing arthropods. The moths are pepeke (insects) and therefore

belong to Te Marae o Tāne (terrestrial ecosystems), and specifically Te Aitanga Pepeke.

Plants, such as the horehound weed, also belong to the domain of Tāne-mahuta, along with the two moths. Māori value

plants in a multifaceted way that recognises their tangible and intangible uses as well as historical and contemporary

importance. This worldview respects past and evolving relationships between people and plants, and connects Māori with

their culture and history. There is hardly a facet of classical Māori culture that did not somehow connect with plants. Māori

regard all native flora and fauna as taonga species and value exotic species for their many beneficial uses. While the

horehound weed is an exotic species, its use overseas in traditional medicine can be considered beneficial.

Plant cultivation is not only important for sustenance and economic reasons but also for connecting Māori to the land, as

the term ‘tāngata whenua’ suggests – people of the land. This relationship is important to Māori irrespective of the size of

the area under cultivation from large scale commercial operations to ngakinga (small domestic plots).

Māori historically used biological control agents, albeit on a domestic scale, to manage pests prior to European contact.

For example, Māori are known to have kept karoro (black-backed gulls) as pets which they trained to eat caterpillars that

infested kumara crops. Post-contact, introduced animals became prominent in the everyday biosecurity of kāinga (homes

and settlements). For example, when Māori began to keep cats their effectiveness in controlling mice and rats was well-

known and appreciated by their owners. Similarly, in rural environments, dogs are used to hunt other pests such as

mustelids, rabbits and possums. Dogs and cats help to suppress rodents and lower risk to poultry and eggs – valuable

home-sourced food for rural whānau. Biological controls are also employed in contemporary gardens where companion

planting is used to attract beneficial insects and repel pests.

A report commissioned by Ngā Pae o te Maramataga , New Zealand’s Māori Centre for Research Excellence, Rongoa

Pastures Heathy Animals Resilient Farms, which includes Horehound Weed as a rongoa (traditional medicane) herb that

could contribute to developing pasture mixes that would be beneficial as rongoa for animals. Is this an aspect that could

be explored further prior to considering the introduction of the two moths?

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August 2018

The horehound plume moth and the horehound clearwing moth and their relationship to New Zealand species

The horehound plume moth and the horehound clearwing moth appear to have no relationship with New Zealand native

moths, which suggests this may not be an issue.

Issues and concerns for Māori

It appears that eradicating horehound weed by conventional means alone (i.e. spraying insecticides) would likely be

impractical, uneconomic and ultimately unsuccessful. Furthermore, any insecticide that posed risk to native or beneficial

species would be regarded as undesirable from a Māori point of view.

In general, Māori favour natural methods for solving environmental issues. Releasing the two moths provides a natural

alternative to possibly more harmful interventions. Firstly, not using insecticides to eradicate horehound weed would avoid

potential adverse impacts on culturally significant species from spays. Secondly, use of insecticides would increase

chemical loading on the environment.

The proposal to release the two moths would be reassuring to Māori involved in primary sector industries. Māori

economic assets are currently valued at around 50 billion dollars, with a significant portion of this being in primary sector

production. Agriculture and horticulture are keystones of Māori development. Māori account for 36% of New Zealand’s

forestry, 30% of lamb production, 12% of sheep and beef units, 10% of dairy production and 10% of kiwifruit production.

Many Māori families and households depend on the primary sector for their livelihoods and well-being. Into the future, as

the Māori economy continues to grow, Māori are likely to be increasingly represented in this sector. Māori are also

involved dry stock operations and are large landholders. The horehound weed could potentially have negative impacts for

these operations and have a substantial adverse economic and social impact on Māori.

Māori will be concerned about whether the two moths can interbreed with native moths, resulting in hybridisation and/or

decimation of the native species. How certain is the applicant that this is not a possibility?

Taha hauora (human health)

No adverse impacts on taha hauora (human health) are anticipated as a result of releasing the two moths. However, as

noted above, the horehound weed is considered a therapeutic plant. Its medical properties have been used for centuries

overseas in traditional medicine to treat various diseases including inflammatory, gastroenteric and respiratory disorders.

It may also have potential in supporting the health of animals.

Taha wairua is spiritual health and well-being obtained through the maintenance of a balance with nature and the

protection of mauri. Restoring ecological equilibrium by controlling an invasive and damaging insect pest will enhance

taha wairua.

Taha hinengaro is mental health and well-being and the capacity to communicate, think and feel. This is about how Māori

see themselves in this universe, their interaction with that which is uniquely Māori and the perception that others have of

them. Thus, doing what is right in terms of tikanga Māori in relation to the horehound weed will engender a sense of

validation and respectability.

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August 2018

Summary of commentary from Māori

As noted in the staff report, the applicant took into consideration some key Māori cultural principles that apply to biological

control proposals in general identified by the Māori Reference Group (MRG) in 2015. The applicant engaged with Māori

via consultation with members of Te Herenga, iwi and Treaty settlement authorities in the South Island, the Ngāpuhi

HSNO komiti and the Ngāi Tahu HSNO komiti.

Members of Te Herenga were given information on the biocontrol agents propose to control horehound in May 2017. No

feedback was received.

The MRG was established to facilitate consultation with Māori interests that may be impacted by the release of new weed

biocontrol agents. The MRG noted that they will not comment on every application for a new pest control agent but

consider the principle level impacts of new biocontrol agents and provide guidance that should be covered in individual

applications.

The MRG noted that the broad cultural principles that apply to considerations on the introduction of new biological control

agents, pest management and environmental protection are Kaitiakitanga and Manaakitanga. The MRG considered that

new biocontrol agents pose the potential to both have a positive impact by aiding in the restoration of balance and

reduction in environmental degradation, and a negative impact by leading to further disturbance.

The applicant did not identify costs or benefits exclusive to Māori as horehound does not seem to have encroached any

taonga species and the host-range of the biocontrol agents does not include native plants (see section 53 to 93).

Furthermore, the number of insects collected around horehound is low and therefore, the impact of the moths will be

minimal.

Horehound is mainly found in the South Island therefore, information was provided to the HSNO komiti of Ngāi Tahu, Ngā

puhi HSNO komiti, and eight iwi and hapū of Te Tau Ihu. No response has been received.

Kaitiakitanga (guardianship & stewardship)

Uncertainties and information gaps aside, this proposal is broadly consistent with principles of kaitiakitanga – stewardship

and guardianship enabling the protection of resources for the current and future welfare of people and the environment.

Kaitiakitanga seeks to maintain balance and harmony within the environment from a perspective of intergenerational

sustainability.

As a general principle, introducing exotic species into the New Zealand environment is culturally undesirable. Approval of

the two moths would address a potentially significant economic problem as well as contribute to the social and cultural

well-being of people and communities. Further information and evidence would definitively determine whether the

premise of kaitiakitanga is met.

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August 2018

Conclusion

Based on the information provided, the benefits of the proposal to introduce the horehound plume moth and the

horehound clearwing moth appear to outweigh its disbenefits. The potential risks to Māori interests may be acceptable

but information gaps remain.

Staff Assessment Report - EPA NZ

Documents

Transcript of Staff Assessment Report - EPA NZ