Interspecific relationships in co-occurring populationsof social parasites and their host ants

MAGDALENA WITEK1*, LUCA PIETRO CASACCI2, FRANCESCA BARBERO2,DARIO PATRICELLI2, MARCO SALA2, SIMONE BOSSI3, MASSIMO MAFFEI3,MICHAL WOYCIECHOWSKI4, EMILIO BALLETTO2 and SIMONA BONELLI2

1Museum and Institute of Zoology, Polish Academy of Sciences, Wilcza 64, 00-679 Warszawa, Poland2Zoology Unit, Department of Life Sciences and Systems Biology, University of Turin, Via AccademiaAlbertina 13, 10123 Torino, Italy3Plant Physiology Unit, Department of Life Sciences and Systems Biology, University of Turin,Innovation Centre, Via Quarello 11 A-1, 10135 Torino, Italy4Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387 Kraków,Poland

Received 12 November 2012; revised 23 January 2013; accepted for publication 23 January 2013

Myrmica ant colonies host numerous insect species, including the larvae of Maculinea butterflies and Microdonmyrmicae hoverflies. Little is known about the interspecific relationships among these social parasites and theirhost ants occurring in sympatric populations. We investigated communities of social parasites to assess thestrategies allowing them to share the same pool of resources (i.e. Myrmica colonies). The present study was carriedout at five sites inhabited by different social parasite communities, each comprising varying proportions ofMaculinea teleius, Maculinea nausithous, Maculinea alcon, and Microdon myrmicae. We investigated their spatialdistributions, host segregation, the degree of chemical similarity between social parasites and hosts, and temporaloverlaps in colony resource exploitation. Spatial segregation among social parasites was found in two populationsand it arises from microhabitat preferences and biological interactions. Local conditions can drive selection on onesocial parasite to use a Myrmica host species that is not exploited by other social parasites. Myrmica scabrinodisand Myrmica rubra nests infested by larvae of two social parasite species were found and the most commonco-occurrence was between Ma. teleius and Mi. myrmicae. The successful coexistence of these two species derivesfrom their exploitation of the host colony resources at different times of the year. © 2013 The Linnean Society ofLondon, Biological Journal of the Linnean Society, 2013, 109, 699–709.

ADDITIONAL KEYWORDS: competition – cuticular hydrocarbons – host–parasite interaction – Maculinea– Microdon – Myrmica.

INTRODUCTION

Social parasites exploit the resources of an entireinsect colony (Nash & Boomsma, 2008). Manyorganisms have evolved to live within ant societies,showing various degrees of interaction, rangingfrom mutualism to parasitism (Hölldobler & Wilson,1990). An estimated 10 000–20 000 morphospecies of

arthropods, most of which are ants themselves(Hölldobler & Wilson, 1990), have evolved as antsocial parasites (Thomas, Schönrogge & Elmes, 2005).Numerous other insects also exploit ant colonies; forexample, Myrmecophila spp. (crickets), Atemeles spp.(beetles), Microdon spp. (hoverflies), and Maculineaspp. (butterflies) (Henderson & Akre, 1986; Thomaset al., 2005).

Among ant social parasites one of the best studiedsystems is the interaction between Maculinea butter-flies and Myrmica ants. Maculinea butterflies are*Corresponding author. E-mail: mawitus@yahoo.co.uk

bs_bs_banner

Biological Journal of the Linnean Society, 2013, 109, 699–709. With 2 figures

© 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 699–709 699

obligate social parasites for which larval survivaldepends on specific food plants and the presence ofMyrmica ants (Thomas, 1980). Maculinea larvae areadopted by Myrmica foragers from early to latesummer and then live inside ant colonies for 11or 23 months (Thomas, Elmes & Wardlaw, 1998;Schönrogge et al., 2000; Witek et al., 2006). Onceinside the ant colony, butterfly larvae use differenttypes of feeding strategies: Maculinea teleius (Berg-strässer, 1779) and Maculinea arion (Linnaeus,1758) are predators that actively prey on the antbrood (Thomas & Wardlaw, 1992), whereas Macu-linea alcon (Denis & Schiffermüller, 1775) andMaculinea rebeli Hirschke 1905 are consideredcuckoo feeders because their larvae are fed directlyby ant workers (Elmes, Wardlaw & Thomas, 1991;Thomas & Elmes, 1998). The feeding behaviour ofMaculinea nausithous (Bergsträsser, 1779) has notbeen fully clarified (Thomas & Elmes, 1998),although recent studies suggest that it is moresimilar to the cuckoo strategy (Patricelli et al.,2010). Each feeding method implies particular costsand benefits. Cuckoo feeders such as Ma. alconlarvae have higher larval survival rates inside thehost colony (Thomas & Elmes, 1998), although thisstrategy apparently results in higher host specificity,at least on a local scale. By contrast, Ma. teleiuspredatory caterpillars have lower larval survivalrates inside Myrmica nests, although the parasitemay be less specialized towards a single ant hostspecies (Thomas & Elmes, 1998).

Microdon myrmicae Schönrogge et al., 2002(Schönrogge et al., 2002) is another social parasitethat exploits Myrmica ants. This syrphid fly belongsto the Microdontinae subfamily, whose members havevarious levels of association with ants (Cheng &Thompson, 2008). Similar to many other Microdonspecies, Mi. myrmicae larvae and pupae are known tolive inside ant colonies, whereas adults are free-flyingorganisms (Duffield, 1981; Witek et al., 2012). In Mayand June, Mi. myrmicae females lay their eggs on thesurface of Myrmica ant nests (Witek et al., 2012).Detailed studies on host ant specificity across Europehave shown that Mi. myrmicae exploits variousMyrmica species, although Myrmica scabrinodisNylander 1846 is the most frequently used (Bonelliet al., 2011).

Most previous studies have dealt with the inter-actions between a single social parasite species andits host ant and investigations on social parasitecommunities are scarce, particularly those address-ing potential competition among parasites (Johnson& Herbers, 2006). This is probably a result of thefact that social parasites of ants are very rare andrestricted to much smaller areas compared to thedistribution of their hosts (Thomas et al., 2005).

Nevertheless, in wet meadows typically dominatedby Molinia spp., a few social parasite species ofMyrmica ants can coexist on a local scale. In pre-vious studies, many localities were found where atleast two (but sometimes three or even four) speciesof social parasites of Myrmica ants occur together(Stankiewicz & Sielezniew, 2002; Zakšek et al., 2005;Tartally 2008; Tartally et al., 2008; Witek et al.,2008; Batáry et al., 2009; Van Langevelde &Wynhoff, 2009; Nowicki et al., 2009; Bonelli et al.,2011; Nowicki & Vrabec, 2011; Korösi et al., 2012).These sites are usually preferred habitats for threeMaculinea butterfly species (i.e. Ma. teleius, Ma.nausithous and Ma. alcon), as well as for the hov-erfly Mi. myrmicae (Stankiewicz, 2003; Nowickiet al., 2007; Witek et al., 2008; Bonelli et al., 2011).The number of such sympatric populations might beunderestimated because it is known that at leastMa. teleius and Ma. nausithous often co-occur inEurope and in the western parts of Central Asia(Woyciechowski, Slowik & Muehlenberg, 2006).Little is known about the distribution of Mi. myr-micae, except that it was frequently found at placesinhabited by Maculinea butterflies (Bonelli et al.,2011). Some studies suggest that various ecologicalfactors may be responsible for the emergence ofsocial parasite ‘hot-spots’ by making ant populationsor individual colonies more vulnerable to socialparasitism (Thomas et al., 2005; Fürst, Durey &Nash, 2011). In the present study, we investigatedseveral sympatric populations of Maculinea butter-flies and Mi. myrmicae hoverfly aiming to assesshow these parasites share the same pool ofresources (i.e. Myrmica colonies). When more thanone conspecific parasite enters the same ant nest,there can be competition between them. In the caseof Maculinea caterpillars, either ‘scramble’ or‘contest’ competition can arise, depending on thelife-history traits of the butterfly (Thomas, Elmes &Wardlaw, 1993). Such competition can affect hostand parasite population dynamics (Thomas et al.,1997), as well as larval developmental strategies(Hovestadt et al., 2007). Given the importance ofcompetition between conspecific social parasites,we can predict that the effects on the populationdynamics of the interacting species should be detect-able also when heterospecific social parasites usingthe same resources coexist in the same ant popula-tion. We hypothesized that competing populations ofsocial parasites might be separated in space, either:(i) by using different parts of the habitat; or (ii) byexploiting different host species, showing differentstrategies of chemical integration; or temporally (iii)by infesting the same Myrmica nests but usingcolony resources at different times of the year. Theabove hypotheses are not mutually exclusive.

700 M. WITEK ET AL.

© 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 699–709

MATERIAL AND METHODSSTUDY SITES

Studies were conducted at five sites: (1) Kosyn(Eastern Poland, 51°23′N/23°34′E); (2) Aleksan-drówka (Eastern Poland in 51°33′N/23°33′E);(3) Wojciechów (Eastern Poland, 51°34′N/23°32′E);(4) Kraków (South Poland, 50°01′N/19°53′E); and(5) Caselette (North-western Italy, 45°70′N/07°29E).These study sites were characterized by differentcommunities of social parasites (see Supporting infor-mation, Table S1). All sites were wet meadows domi-nated by Molinia caerulea. Sanguisorba officinalis,the larval food plant of Ma. teleius and Ma.nausithous, was present at four sites (excludingWojciechów), whereas Gentiana pneumonanthe, thelarval food plant of Ma. alcon, was present at Case-lette, Kraków and Wojciechów.

DATA COLLECTION

To establish the host ant specificity and survival ratesof parasitic larvae, data were collected at the end ofthe parasite larval development (June). At Caselette,Aleksandrówka, and Wojciechów, Maculinea foodplants had patchy and restricted distributions,meaning that some parts of the habitat had no (orcontained only single) individuals of Maculinea foodplants. At these three sites, we collected data bothwithin and outside the food plant patches. Maculinealarvae could be found only in patches covered by their

food plants, whereas Mi. myrmicae was able to infestany Myrmica colony. We tested for possible spatialsegregation between Maculinea and Mi. myrmicae onthe basis of butterfly food plant distributions. Bycontrast, at Kraków and Kosyn, S. officinalis waswidespread, and all investigated ant nests wereinside Maculinea food plant patches.

At all sites within Maculinea food plant patches, wesearched for Myrmica ant colonies located within 2 mof the butterfly food plants (S. officinalis and/orG. pneumonanthe) because this is the average forag-ing distance of Myrmica ants (Elmes et al., 1998).This procedure allowed us to assume that all exam-ined nests were potentially available for all socialparasite species occurring at the site. Myrmica neststhat were located outside Maculinea butterfly foodplant patches and potentially infested only by Mi.myrmicae were searched for in a random way. Duringsampling procedures, Myrmica nests were openedto determine the presence/absence of Maculinea(Sliwinska et al., 2006) and Mi. myrmicae larvae,pupae, and exuviae. From each Myrmica colony, tento 20 ant workers were collected and preserved in70% ethanol. The key proposed by Czechowski,Radczenko & Czechowska (2002) was used for iden-tification of ant species. A total of 656 Myrmica nestswere studied. Details on the spatial distribution andcomposition of the Myrmica ant communities aredescribed in Table 1 (see also the Supporting infor-mation, Table S1).

Table 1. Number and percentage of nests, and number and percentage of social parasite larvae, reared by Myrmicacolonies showing single and double infestation

Site and ant species

Number ofinfestednests

Number (%)of singleinfested nests

Number (%)of doubleinfested nests

Number (%)of larvae insidesingle infestednests

Number (%)of larvaeinside doubleinfested nests

KrakówMyrmica scabrinodis 32 26 (81%) 6 (19%) 34 (67%)tel, 17 (33%)tel,

13 (54%)mic 11 (46%)mic

KosynMyrmica scabrinodis 12 11 (92%) 1 (8%) 10 (77%)tel, 3 (23%)tel,

3 (60%)mic 2 (40%)mic

Myrmica rubra 5 3 (60%) 2 (40%) 9 (14%)tel 55 (86%)tel,36 (100%)nau

CaseletteMyrmica scabrinodis (zone with

both Maculinea food plants)17 16 (94%) 1 (6%) 52 (94.5%)alc, 3 (5.5%)alc,

5 (100%)mic 5 (100%)tel

Myrmica scabrinodis (zone withSanguisorba officinalis)

12 10 (83%) 2 (17%) 9 (60%)tel, 6 (40%)tel,6 (54.5%)mic 5 (45.5%)mic

tel, Maculinea teleius; nau, Maculinea nausithous; alc, Maculinea alcon; mic, Microdon myrmicae.

CO-OCCURRING SOCIAL PARASITES OF ANTS 701

© 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 699–709

COMPARISON OF MI. MYRMICAE AND MA. TELEIUS

LIFE CYCLE

Data for the comparison of Mi. myrmicae and Ma.teleius life cycle focused on larval development insideMyrmica colonies originate from our former studies(Witek et al., 2011; 2012).

SURFACE CHEMISTRY

Social parasite integration into host colonies can bereflected in chemical profile similarities betweensocial parasite larvae and their Myrmica host ants.Therefore, we sampled cuticular chemical profiles ofindividual larvae and host ants from Kraków andKosyn (Poland) in June 2010. Ant worker cuticularchemicals were sampled from six colonies of My.scabrinodis, five colonies of My. rubra (Linnaeus1758), and two colonies of My. ruginodis Nylander1846. Surface chemicals were also sampled from para-sitic larvae: three of Ma. alcon (all found inside My.scabrinodis nests), four of Ma. nausithous (collectedfrom My. rubra colonies), 16 of Ma. teleius (eight inMy. scabrinodis, six in My. rubra, two in My. rugino-dis colonies), and three of Mi. myrmicae (collectedfrom My. scabrinodis colonies). Cuticular hydrocar-bons were extracted in the laboratory from singlepost-adoption caterpillars, as well as from fiveMyrmica workers from each colony. Extracts wereanalyzed by gas-chromatography/mass spectrometryusing standard methods (for further information, seethe Supporting information, Table S1).

STATISTICAL ANALYSIS

Fisher’s exact test was used to compare the degreeof nest infestation among habitat patches in Case-lette. The ant host specificity of Ma. teleius in theKraków and Kosyn populations was calculated bytwo separate tests. (1) Fisher’s exact test: the pro-portion of available nests of each Myrmica species(expected value) was compared with the proportioncontaining Ma. teleius larvae/pupae (observedvalue). (2) A general linear model for overdisperseddata (negative binominal distribution) comparingthe numbers of Ma. teleius specimens found withinthe nests of each Myrmica species. Data concerningMy. ruginodis nests from Kosyn were excluded fromthis analysis because only two nests were found.General linear model analysis allows testing forquantitative differences between the numbers of Ma.teleius reared by different Myrmica species. Themethods used to analyze data on cuticular hydro-carbons are described in the Supporting information(Table S1).

RESULTSSPATIAL SEGREGATION OF SOCIAL PARASITES

Spatial segregation was tested for three populations:Caselette, Aleksandrówka, and Wojciechów. In Case-lette, only My. scabrinodis colonies were present. Inan area containing both species of Maculinea foodplants, we found 15 (30%) nests exploited by Ma.alcon, two nests (4%) infested by Mi. myrmicae (one ofthem also contained Ma. alcon), and one nest (2%)with Ma. teleius. In the area where only S. officinaliswas present, ten nests (20%) were infested by Ma.teleius and four (8%) were infested by Mi. myrmicae.In the area lacking any butterfly food plants andhence having no Maculinea, 25 (25%) Myrmica colo-nies were infested by Mi. myrmicae. The proportion ofnests infested by Ma. teleius was significantly higherin the part of the meadow where only S. officinaliswas present compared to the zone where both Macu-linea food plants were present (Fisher’s exact test,P = 0.003). Significant differences in the proportion ofnests infested by Mi. myrmicae were observed acrossthe three zones (Fisher’s exact test, P < 0.001). Pair-wise comparisons demonstrated that the proportion ofnests infested by Mi. myrmicae was significantlyhigher outside of the area with butterfly food plantsthan in the area where both plants were present(Fisher’s exact test, P = 0.004).

At Aleksandrówka, only My. scabrinodis nests wereinfested by social parasites. In the area containingS. officinalis, 98% of the nests were of My. scabrino-dis. Six (12%) of these nests were exploited by Ma.teleius and none contained Mi. myrmicae, whereas, inthe area lacking Ma. teleius food plants, only 74% ofthe Myrmica colonies belonged to My. scabrinodis andsix of these (8%) were infested by Mi. myrmicae (seeSupporting information, Table S1).

Also at Wojciechów, only My. scabrinodis colonieswere exploited by social parasites. All infested nestswere found in an area where G. pneumonanthe wasgrowing; My. scabrinodis formed 95% of the nestpopulation, two nests (3%) were infested by Ma. alconlarvae and another two (3%) by Mi. myrmicae.

DOUBLE INFESTATIONS

Nests with double infestations were found at Case-lette (three nests), Kosyn (three nests), and Kraków(six nests) and they belonged to either My. scabrino-dis or to My. rubra. Depending on ant species andpopulation, the percentage of double infestationamong parasitized nests ranged from six to 40(Table 1). Also, the proportion of parasitic larvaereared in nests with double infestation was high and,in some situations, all larvae of a particular socialparasite species were found in such colonies (Table 1).

702 M. WITEK ET AL.

© 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 699–709

The most common co-occurrence was found betweenMi. myrmicae and Ma. teleius (nine out of 12 cases)and the mean ± SD number of parasitic larvae was4.8 ± 2.18.

COMPARISON OF MI. MYRMICAE AND MA. TELEIUS

LIFE CYCLE

A comparison of the life cycle of Mi. myrmicae andMa. teleius is shown in Figure 1. The most intensiveMa. teleius larval growth associated with exploitationof host colony resources occurs from April to June,which corresponds to the period when Mi. myrmicaeis present in the stage of pupa, adult or egg, and isnot using colony resources. Microdon myrmicaelarvae mostly grow from the beginning of July toSeptember, which is the time when Ma. teleius ispresent in the stage of pupae, adults, and eggs, aswell as I–III instar larvae feeding on the specific foodplants (Fig. 1).

SEGREGATION AMONG HOST ANT SPECIES

Myrmica scabrinodis was the only host ant speciesexploited by social parasites at Caselette, Wojciechów,and Aleksandrówka. At Caselette, My. scabrinodiswas the only Myrmica species present, whereas, atthe other two sites, it was the most abundant species(83% in Aleksandrówka and 81.5% in Wojciechów).Similarly, My. scabrinodis was the dominant speciesat Kraków and Kosyn, although other Myrmicaspecies were also used as hosts in these areas.

At Kraków, My. scabrinodis was the only hostexploited by Ma. alcon and Mi. myrmicae (see Sup-porting information, Table S1), whereas Ma. teleiusexploited all Myrmica species present. The proportionof Ma. teleius larvae/pupae reared by variousMyrmica host species differed significantly (Fisher’sexact test, P = 0.01), although pairwise comparisonsamong Myrmica host species did not reveal any sig-nificant differences. Results obtained by the generallinear model did not reveal any significant differencein the numbers of Ma. teleius reared by variousMyrmica host species (Table 2).

In Kosyn, four Myrmica species were found, threeof which were exploited by resident social parasites(see Supporting information, Table S1). Microdonmyrmicae exclusively exploited My. scabrinodis,whereas Ma. nausithous was found only inside My.rubra nests. Maculinea teleius exploited threeMyrmica species: My. rubra, My. scabrinodis, and My.gallienii Bendroit 1920. The proportion of Ma. teleiuslarvae/pupae reared by the various Myrmica hostspecies differed significantly (Fisher’s exact test,P < 0.001) and pairwise comparisons performed byFisher’s exact test indicated that Ma. teleius larvaeexploited My. rubra nests to a significantly greaterdegree than nests of My. scabrinodis (P < 0.001) orMy. gallienii (P < 0.001). Similar results wereobtained by the general linear model (Table 2).

SURFACE CHEMISTRY

Gas-chromatography analysis revealed a total of 111compounds across the pooled samples, with branchedalkanes being the most abundant hydrocarbons. Wedid not find any significant difference in the variabil-ity of cuticular hydrocarbon profiles of samples (My.scabrinodis, My. rubra, Ma. teleius) collected fromdifferent sites with respect to samples obtained fromthe same site (PANOSIM > 0.05 for each species). Datacollected from Kraków and Kosyn were thereforepooled for analysis.

A cluster representation of the 39 samples, basedon the fourth root-transformed relative abundances ofall recorded hydrocarbons, yielded a good discrimina-tion between the three Myrmica ant species and thefour parasite species (Fig. 2A). Pairwise within-

Figure 1. Comparison of the life cycle of Maculineateleius (inner circle) and Microdon myrmicae (outer circle).Dark grey, intensive larval growth of social parasite insideMyrmica colony connected with high exploitation of hostcolony resources. Microdon myrmicae: II and III instarlarvae. Maculinea teleius: IV instar larva. Light greycolour, diapause, larvae of social parasite stay inside hostnest but slightly use colony resources. Microdon myrmicae:III instar larva. Maculinea teleius: IV instar larva. Whitecolour, during this period, the social parasite does not usehost colony resources. Microdon myrmicae: pupa, adult,egg, I instar larva. Maculinea teleius: pupa, adult, egg,I–III instar larvae. The data used for this comparison arefrom Witek et al. (2011, 2012).

CO-OCCURRING SOCIAL PARASITES OF ANTS 703

© 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 699–709

species comparisons showed that My. scabrinodis hadthe lowest within-species similarity (approximately67%), whereas My. rubra and My. ruginodis had highwithin-species similarities (approximately 78% and89%, respectively). Analysis of similarity (ANOSIM)determined that six out of the seven analyzed specieswere significantly distinct from each other (P < 0.05),except Ma. alcon, which clustered together with My.scabrinodis, its host ant species (Fig. 2A). The hydro-carbon samples of Ma. teleius, which was the onlyparasite found within the nests of three differentMyrmica species presented a rich chemical profile(Ma. teleiusruginodis: 57.0 ± 0.0 peaks; Ma. teleiusscabrinodis:69.0 ± 7.8 peaks; Ma. teleiusrubra: 69.0 ± 7.8 peaks).Also, Ma. nausithous chemical profiles were charac-terized by a high number of hydrocarbons (50 ± 13peaks), whereas Ma. alcon larvae had considerablyfewer cuticular hydrocarbons (a maximum of 28peaks) than Ma. teleius or Ma. nausithous. The Ma.teleius chemical profile was 32%, which is similar tothat of My. ruginodis workers and 50% similar to thatof My. rubra. Maculinea nausithous, which exclu-sively exploits My. rubra colonies, clustered togetherwith Ma. teleius samples but had lower chemicalsimilarity (43%) with its host species than thatobserved for Ma. teleius caterpillars (51%). Maculineaalcon showed the highest pairwise similarity(approximately 67%) with its exclusive host ant, My.scabrinodis (Fig. 2B). The parasite species showingthe most peculiar and simple hydrocarbon profile,with an average of just eight hydrocarbon peaks, wasMi. myrmicae, which exclusively infested My. scabri-nodis colonies.

DISCUSSION

Sympatric populations of ant social parasites employa number of methods to share the same pool ofresources (i.e. colonies of their host ants). The spatialdistribution of Maculinea butterflies is strictly asso-ciated with the presence of their food plants. Conse-quently, only Myrmica nests located in the vicinity ofthese plants can be infested by butterfly larvae. Bycontrast, Mi. myrmicae females may apparently laytheir eggs on the surface of any Myrmica nest occur-ring in any part of the meadow. At three out of fivestudy sites, the distribution of Maculinea food plantsallows testing of the spatial distributions of varioussocial parasite species, and the data collected at twoof these sites clearly showed that they can be spa-tially segregated. At Caselette, we distinguished threezones, each dominated by one social parasite species.A similar spatial segregation pattern was detected atAleksandrówka, where no Myrmica colonies wereinfested by Mi. myrmicae in the part of the meadowwhere Ma. teleius food plants were present. SpatialT

able

2.R

esu

lts

ofge

ner

alli

nea

rm

odel

anal

ysis

com

pari

ng

the

nu

mbe

rsof

Mac

uli

nea

tele

ius

spec

imen

sfo

un

dw

ith

inth

en

ests

ofea

chM

yrm

ica

spec

ies

atK

rakó

wan

dK

osyn

(k-d

ispe

rsio

npa

ram

eter

ofth

en

egat

ive

bin

omia

ldi

stri

buti

onw

as0.

725

for

Kra

ków

and

0.15

8fo

rK

osyn

)

Sit

eH

ost

spec

ies

Hos

tsp

ecie

s

Nu

mbe

rof

Mac

uli

nea

tele

ius

larv

aein

side

hos

t*n

ests

(mea

n±

SE

)L

ikel

ihoo

dra

tio

d.f.

P

Kos

ynM

yrm

ica

rubr

ave

rsu

sM

yrm

ica

gall

ien

i4.

57±

3.10

6.61

81

0.01

0M

yrm

ica

gall

ien

ive

rsu

sM

yrm

ica

scab

rin

odis

0.19

±0.

140.

000

10.

984

Myr

mic

asc

abri

nod

isve

rsu

sM

yrm

ica

rubr

a0.

19±

0.07

15.1

421

<0.

001

Kra

ków

Myr

mic

aru

bra

vers

us

Myr

mic

aru

gin

odis

1.00

±0.

330.

237

10.

627

Myr

mic

aru

gin

odis

vers

us

Myr

mic

asc

abri

nod

is0.

63±

0.04

0.14

81

0.70

0M

yrm

ica

scab

rin

odis

vers

us

Myr

mic

aru

bra

0.73

±0.

020.

119

10.

731

Sig

nifi

can

tre

sult

sar

esh

own

inbo

ld.

Res

ult

ssh

owin

gth

em

ean

±S

En

um

ber

ofM

a.te

leiu

sla

rvae

refe

rto

Myr

mic

asp

ecie

sn

oted

inth

efi

rst

colu

mn

.

704 M. WITEK ET AL.

© 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 699–709

segregation can result from a mixture of variousfactors and the simplest explanation can be associ-ated with slightly different microhabitat preferencesbecause, for example, Mi. myrmicae females prefer tolay their eggs in very humid habitat patches (Bonelliet al., 2011). Another possible explanation might be aconsequence of competition among different species ofsocial parasites, as well as their influence on hostcolony behaviour; however, to explain these possiblemechanisms, further investigations are needed.

In the present study, only at Caselette was it pos-sible to detect spatial segregation between differentMaculinea species. In other places, only Ma. teleiuswas sufficiently abundant, whereas samples of otherbutterfly species were too small to make any spatialanalysis. Nevertheless, previous studies (Nowickiet al., 2005, 2007; Batáry et al., 2009; Van Langevelde& Wynhoff, 2009; Korösi et al., 2012), based on dataobtained on adult butterflies, showed that, in sympat-ric populations of Ma. teleius and Ma. nausithous,these two species are spatially separated, mostly as aresult of different microhabitat preferences. Theseresults can be viewed both in association with the useof different hosts ants and with the implementation of

different strategies of chemical integration into thehost colonies corresponding to different degrees ofhost-specificity. Our data clearly show that Ma. alconand Mi. myrmicae are highly specific with respect toMy. scabrinodis, whereas Ma. nausithous is specific toMy. rubra. Maculinea teleius is considered the mostgeneralist species among all Maculinea butterflies(Stankiewicz & Sielezniew, 2002; Woyciechowskiet al., 2006; Tartally & Varga, 2008; Witek et al.,2010). At Kraków and Kosyn, where several Myrmicaspecies were abundant, Ma. teleius uses all availablehost species. Our data concur with those obtained inprevious studies carried out in the Kraków region(Witek et al., 2010), which indicate that colonies ofMy. rubra and My. ruginodis can be used by Ma.teleius larvae even more successfully than nests ofMy. scabrinodis. It should be noted that, in thesepopulations, Ma. teleius competes with Ma. alcon andMi. myrmicae larvae for access to My. scabrinodiscolonies. In such situations, competition should posesufficiently strong selection on Ma. teleius populationsso that they use Myrmica host species not exploitedby other social parasites. In general, the local pat-terns of host ant specificity observed in Ma. teleius

Figure 2. A, dendrogram representing the relationship between the hydrocarbon signatures of the three ant species(Myrmica scabrinodis, Myrmica rubra, and Myrmica ruginodis) and the larvae of the four social parasite species foundinside these Myrmica host colonies: Maculinea alcon (alc), Maculinea teleius (tel), Maculinea nausithous (nau), andMicrodon myrmicae (mic). B, mean Bray–Curtis similarities (%; ± SE) between the chemical profiles of the host antspecies (squares) and their parasites (circles). Overlapping circles indicate the parasite species that were found togetherin the same colonies.

CO-OCCURRING SOCIAL PARASITES OF ANTS 705

© 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 699–709

might vary depending on the presence/absence ofother competitors. According to predictions of thegeographical mosaic model (Thompson, 1999), geo-graphical variation in the strengths of coevolutionmay lead to differences in host ant use at both localand regional levels. Thus, in some cases, not only theavailability of host species, but also the presence ofother competitors might shape coevolution betweenparticular species of social parasites and of theirhosts.

Although the sample size for some of the speciesconsidered in the present study is small, the resultsobtained from the analysis of post-adoption chemicalprofiles reflect degrees of integration inside the hostcolony and explain well the level of species-specificityobserved for the various social parasites in studypopulations. It is known that Maculinea caterpillarsinfiltrate Myrmica colonies mostly by mimicking thecuticular hydrocarbon composition used by the antsfor nest mate recognition (Akino et al., 1999;Schönrogge et al., 2004; Nash et al., 2008). Abandon-ing the food plant, Maculinea larvae possess a chemi-cal profile weakly mimicking that of their host ants(Nash et al., 2008). Such behaviour has not only beendemonstrated for the cuckoo feeders (Akino et al.,1999; Elmes et al., 2002; Schönrogge et al., 2004), butalso it is conceivable for the predatory species. Oncethe caterpillars are retrieved inside the ant colonies,the chemical composition of their cuticle changes andthe number of hydrocarbons increases to mimic moreclosely the host ant’s profile (Akino et al., 1999; Elmeset al., 2002; Schönrogge et al., 2004). In both popula-tions, Ma. alcon and Mi. myrmicae exclusively exploitMy. scabrinodis colonies. Data on the chemical pro-files of their post-adoption larvae show two differentpatterns of chemical similarity with respect to theMyrmica host species. Maculinea alcon larvae arehighly integrated within their host colonies andachieve almost 70% chemical similarity to their hostworkers (Fig. 2), which is comparable to the degree ofsimilarity found among My. scabrinodis colonies.Even if data are not available on the chemical profilesoccurring during the pre-adoption phase, it is possibleto assume that, after adoption, Ma. alcon caterpillarsdeveloped more complex chemical profiles eitherthrough the acquisition of hydrocarbons, by inducingdirect feeding by worker ants, or perhaps through thesynthesis of new hydrocarbons. Schönrogge et al.(2004) demonstrated that the latter option is imple-mented in a sister species of Ma. alcon (i.e. Ma. re-beli), which, in this way, improves and amplifies itsmimicry to Myrmica schencki. The chemical similar-ity between Mi. myrmicae and its host ants is muchlower than that of Ma. alcon, although its hydrocar-bon profile is still more similar to My. scabrinodisthan to any other Myrmica species. Relative to Macu-

linea larvae and Myrmica workers, the chemicalprofile of Mi. myrmicae exhibits few cuticular hydro-carbons, all at low concentrations, thereby indicatingthat it uses an improved ‘chemical insignificance’strategy (Lenoir et al., 2001) to survive withinMyrmica colonies. Such a poorly developed chemicalprofile might be explained by the fact that, aftersummer, Mi. myrmicae larvae appear to stop feedingon the ant brood and do not have many furthercontacts with workers, therefore becoming unable toacquire the more complex chemical profiles character-istic for Ma. teleius and Ma. nausithous. Moreover, inanalogy to Microdon mutabilis, which parasitizescolonies of Formica lemani (Schönrogge et al., 2008),we can assume that Mi. myrmicae females, followingthe olfactory trace of one or more specific chemicals,may recognize and lay their eggs in the host nests ofMy. scabrinodis, thereby maximizing the fitness oftheir offspring. For these reasons, it is likely thatlarvae having developed in the ‘correct’ host colony donot need to be chemically mimetic to integrate insideit, and simply use a chemical insignificance strategyto prey on the ant brood undisturbed. In the presentstudy, Ma. nausithous was observed only at Kosyn,although, in previous investigations, it also exploitedMy. rubra in the Kraków (Witek et al., 2008; Patricelliet al., 2010). Maculinea nausithous is highly specificto My. rubra colonies (Thomas et al., 1989;Stankiewicz & Sielezniew, 2002; Tartally & Varga,2005; Witek et al., 2008). However, its larvae do notreach the same level of chemical similarity as Ma.alcon does within My. scabrinodis colonies and it isalso lower than that of Ma. teleius larvae, whichshare the same My. rubra colonies. Nevertheless, itschemical similarity is sufficiently high (approximately43%) to successfully exploit colony resources. Thecuticular hydrocarbon profiles of post-adoption Ma.teleius larvae achieved the highest degree of similar-ity with the host workers of My. rubra colonies(Fig. 2), which may explain why Ma. teleius is able tosuccessfully exploit colonies of this ant species both atKraków and Kosyn, and might also indicate an ances-tral association with this Myrmica species. Variouschemical integration strategies could therefore havestabilized over time, thereby allowing a variety ofsocial parasites to survive at the expense of the sameant community of the genus Myrmica.

The results of the present study show that socialparasites are able to exploit the same Myrmica colo-nies and that most doubly-infested nests belong toMy. scabrinodis, which was the most abundantMyrmica species at all study sites. This is not sur-prising because this ant species is the only host of Ma.alcon and Mi. myrmicae and is also used by Ma.teleius. Another Myrmica species that could be poten-tially infested by more than one parasite species is

706 M. WITEK ET AL.

© 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 699–709

My. rubra, which is a host of Ma. nausithous and Ma.teleius. The highest number of parasitized nests werefound at Kraków, where almost half of the My. scabri-nodis colonies were infested by parasitic larvae and,among them, 19% were doubly infested. The percent-age of Ma. teleius and Mi. myrmicae larvae reared bythese colonies was also high, and 33% and 46%,respectively, of larvae were found inside doublyinfested nests. This result shows that doubleinfestation is not such a rare phenomenon and isparticularly interesting because even intra-speciescompetition among Maculinea larvae has crucial con-sequences for both larval survival and populationdynamics (Thomas et al., 1993). The most commonlyobserved double parasitic co-existing observed insideMyrmica nests was between Mi. myrmicae and Ma.teleius. Because our data were collected at the end ofthe larval development period, the co-occurrence ofthese social parasites indicates that they were able toshare the resources afforded by the same host colony.We found Mi. myrmicae exuviae in most of thesenests, indicating that this social parasite successfullycompleted its life cycle inside the host colonies. Theability to coexist in the same host colony might resultfrom temporal segregation in resource exploitation.The highest feeding activity of Mi. myrmicae larvaeoccurs from July to September (Witek et al., 2012),when Maculinea butterflies are present as pupae,imagoes and early-instar larvae feeding at specificfoodplants, and are therefore not yet exploiting colonyresources (Fig. 1). By contrast, the most intensivefeeding activity found for the majority of Maculinealarvae occurs before pupation, between the end ofApril until middle of June (Thomas et al., 1998;Schönrogge et al., 2000; Witek et al., 2006; Sielezniew& Stankiewicz, 2007), which is a time when Mi.myrmicae is present as pupa, imago or egg, and doesnot use host colonies resources. Therefore, this tem-poral segregation of feeding activities might allowboth social parasite species to undergo larval devel-opment inside the same host colony. It is important tonote that, in some populations of Ma. teleius and Mi.myrmicae, especially those from northern Europe, 1-and 2-year developed larvae can coexist (Schönroggeet al., 2000; Witek et al., 2006). Therefore, the mecha-nism of interaction between these two social para-sites, as well as their population dynamics, mightvary across their ranges.

To our knowledge, the present study has investi-gated, for the first time, how ant social parasitesoccurring in sympatric populations share the samepool of resources (i.e. ant colonies). Although thedatabase reported in the present study is not verypowerful (mostly as a result of difficulties in collectingsocial parasite material) and, although most of ourconclusions are based on field observations, we have

been able to distinguish patterns of sharing Myrmicacolonies among different social parasite species. It isassumed that the effects of Maculinea butterfly larvaeon host colony fitness are severe (Thomas & Wardlaw,1992; Nash et al., 2008), such that strong competitionamong larvae of these social parasites is expected tooccur. As hypothesized, we found context-dependentsegregation among social parasites either by spaceand host-ant species, as well as by temporal segrega-tion in colony resource exploitation. In the case ofspatial segregation, probably a mixture of variousecological factors is responsible for the observedpattern. When environmental conditions do not allowfor spatial segregation, the populations of somesocial parasite species may be forced to use Myrmicahost species that are not exploited by other morespecialized competitors. Finally, the most commonco-occurrence between social parasites was found forspecies that exploit host resources at different timesof the year. Thus, temporal segregation allows themto survive inside the same host nest and avoid directcompetition for resources.

ACKNOWLEDGEMENTS

We would like to thank Anna Amirowicz, ElzbietaRozej, Joanna Kajzer, and Paweł Mielczarek for theirhelp with the fieldwork in Kraków, as well as GrahamElmes and four anonymous referees for providingvaluable comments on earlier version of manuscript.This research was funded within the project CLIMIT(Climate Change Impacts on Insects and their Miti-gation; Settele & Kühn, 2009; Thomas, Simcox &Clarke, 2009) funded by DLR-BMBF (Germany),NERC and DEFRA (UK), ANR (France), Formas(Sweden), and Swedish EPA (Sweden) through theFP6 BiodivERsA Eranet, as well as by the project ‘Amultitaxa approach to study the impact of climatechange on the biodiversity of Italian ecosystems’ ofthe Italian Ministry of Education, University andResearch (MIUR). M. Witek was financially supportedby a grant from the Polish National Science Centre(post-doctoral internship – No. DEC-2012/04/S/NZ8/00218).

REFERENCES

Akino T, Knapp JJ, Thomas JA, Elmes GW. 1999. Chemi-cal mimicry and host specificity in the butterfly Maculinearebeli, a social parasite of Myrmica ant colonies. Proceedingsof the Royal Society of London Series B, Biological Sciences266: 1419–1426.

Batáry P, Korösi A, Örvössy N, Köver S, Peregovits L.2009. Species-specific distribution on two sympatric Macu-linea butterflies across different meadow edges. Journal ofInsect Conservation 13: 223–230.

CO-OCCURRING SOCIAL PARASITES OF ANTS 707

© 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 699–709

Bonelli S, Witek M, Canterino S, Sielezniew M, Stank-iewicz A, Tartally A, Balletto E, Schönrogge K. 2011.Distribution, host specificity and the potential for crypticspeciation in hoverfly Microdon myrmicae (Diptera: Syrphi-dae), a social parasite of Myrmica ants. Ecological Entomol-ogy 36: 135–143.

Cheng XY, Thompson FC. 2008. A generic conspectus of theMicrodontinae (Diptera: Syrphidae) with the description oftwo new genera from Africa and China. Zootaxa 1879:21–48.

Czechowski W, Radczenko A, Czechowska W. 2002. Theants (Hymenoptera, Formicidae) of Poland. Warsaw: MIZPAN.

Duffield RM. 1981. Biology of Microdon fuscipennis (Diptera:Syrphidae) with interpretation of the reproductive strate-gies of Microdon species found north of Mexico. Proceedingsof the Entomological Society of Washington 84: 716–724.

Elmes GW, Akino T, Thomas JA, Clarke RT, Knapp JJ.2002. Interspecific differences in cuticular hydrocarbon pro-files of Myrmica ants are sufficiently consistent to explainhost specificity by Maculinea (large blue) butterflies. Oeco-logia 130: 525–535.

Elmes GW, Thomas JA, Wardlaw JC, Hochberg ME,Clarke RT, Simcox DJ. 1998. The ecology of Myrmicaants in relation to the conservation of Maculinea butterflies.Journal of Insect Conservation 2: 67–78.

Elmes GW, Wardlaw JC, Thomas JA. 1991. Larvae ofMaculinea rebeli, a large blue butterfly, and their Myrmicahost ants: patterns of caterpillar growth and survival.Journal of Zoology 224: 79–92.

Fürst M, Durey M, Nash DR. 2011. Testing the adjustablethreshold model for intruder recognition on Myrmica ants inthe context of a social parasite. Proceedings of the RoyalSociety of London Series B, Biological Sciences 279: 516–525.

Henderson G, Akre R. 1986. Biology of the myrmecophilouscricket, Myrmecophila manni, (Orthoptera: Gryllidae).Journal of the Kansas Entomological Society 59: 454–467.

Hölldobler B, Wilson EO. 1990. The ants. Berlin: SpringerVerlag.

Hovestadt T, Mitesser O, Elmes GW, Thomas JA, Hoch-berg ME. 2007. An evolutionarily stable strategy model forthe evolution of dimorphic development in the butterflyMaculinea rebeli, a social parasite of Myrmica ant colonies.American Naturalist 169: 466–480.

Johnson CA, Herbers JM. 2006. Impact of parasite sympa-try on the geographic mosaic of coevolution. Ecology 87:382–394.

Korösi A, Örvössy N, Batáry P, Harnos A, Peregovits L.2012. Different habitat selection by two sympatric Macu-linea butterflies at small spatial scale. Insect Conservationand Diversity 5: 118–126.

Lenoir A, D’ettorre P, Errard C, Hefetz A. 2001. Chemicalecology and social parasitism in ants. Annual Review ofEntomology 46: 573–599.

Nash DR, Als TD, Maile R, Jones G, Boomsma JJ. 2008.A mosaic of chemical coevolution in a large blue butterfly.Science 319: 88–90.

Nash DR, Boomsma JJ. 2008. Communication betweenhosts and social parasites. In: d’Ettorre P., Hughes D.P., eds.Sociobiology of communication: an interdisciplinary perspec-tive. 55. Oxford: Oxford University Press.

Nowicki P, Bonelli S, Barbero F, Balletto E. 2009. Rela-tive importance of density-dependent regulation and envi-ronmental stochasticity for butterfly population dynamics.Oecologia 161: 227–239.

Nowicki P, Pepkowska A, Kudłek J, Skórka P,Witek M, Settele J, Woyciechowski M. 2007. From meta-population theory to conservation recommendations:lessons for special occurrence and abundance patterns ofMaculinea butterflies. Biological Conservation 140: 119–129.

Nowicki P, Vrabec V. 2011. Evidence for positive density-dependent emigration in butterfly metapopulations. Oecolo-gia 167: 657–665.

Nowicki P, Witek M, Skórka P, Settele J, Woycie-chowski M. 2005. Population ecology of the endangeredbutterflies Maculinea teleius and M. nausithous, and itsimplications for conservation. Population Ecology 47: 409–417.

Patricelli D, Witek M, Barbero F, Casacci LP, Bonelli S,Balletto E. 2010. Evidence of high larval host ant specifi-city in the first post adoption phase for the myrmecophilousbutterfly Phengaris (Maculinea) nausithous (Lepidoptera:Lycaenidae). Sociobiology 55: 861–870.

Schönrogge K, Barr B, Wardlaw JC, Napper E, GardnerMG, Breen J, Elmes GW, Thomas JA. 2002. Whenrare species become endangered: cryptic speciation inmyrmecophilous hoverflies. Biological Journal of theLinnean Society 75: 291–300.

Schönrogge K, Napper EKV, Birkett MA, Woodcock CM,Pickett JA, Wadhams LJ, Thomas JA. 2008. Host rec-ognition by the specialist hoverfly Microdon mutabilis, asocial parasite of the ant Formica lemani. Journal of Chemi-cal Ecology 34: 168–178.

Schönrogge K, Wardlaw JC, Peters AJ, Everett S,Thomas JA, Elmes GW. 2004. Changes in chemical sig-nature and host specificity from larval retrieval to full socialintegration in the myrmecophilous butterfly Maculinearebeli. Journal of Chemical Ecology 30: 91–107.

Schönrogge K, Wardlaw JC, Thomas JA, Elmes GW.2000. Polymorphic growth rates in myrmecophilous insects.Proceedings of the Royal Society of London Series B, Bio-logical Sciences 267: 771–777.

Settele J, Kühn E. 2009. Insect conservation. Science 325:41–42.

Sielezniew M, Stankiewicz A. 2007. Differences in thedevelopment of the closely related myrmecophilous butter-flies Maculinea alcon and Maculinea rebeli (Lepidoptera:Lycaenidae). European Journal of Entomology 104: 433–444.

Stankiewicz A. 2003. Hoverfly Microdon myrmicae Schön-rogge et al., 2002 (Diptera: Syrphidae) in Poland. PolishJournal of Entomology 75: 145–151.

Stankiewicz A, Sielezniew M. 2002. Host specificity ofMaculinea teleius Bgstr. and M. nausithous Bgstr.

708 M. WITEK ET AL.

© 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 699–709

(Lepidoptera:Lycaenidae). The new sight. Annales Zoologici52: 403–408.

Sliwinska EB, Nowicki P, Nash DR, Witek M, Settele J,Woyciechowski M. 2006. Morphology of caterpillars andpupae of European Maculinea species (Lepidoptera: Lycae-nidae) with identification table. Entomologica Fennica 17:351–358.

Tartally A. 2008. Myrmecophily of Maculinea butterflies inthe Carpathian Basin (Lepidoptera: Lycaenidae). Abstract ofthe PhD thesis. University of Debrecen.

Tartally A, Nash DR, Lengyel S, Varga Z. 2008. Patternsof host ant use by sympatric populations of M. alcon andM. rebeli in the Carpathian Basin. Insectes Sociaux 55:370–381.

Tartally A, Varga Z. 2005. Myrmica rubra (Hymenoptera:Formicidae): the first data on host-ant specificity of Macu-linea nausithous (Lepidoptera: Lycaenidae) in Hungary.Myrmecologische Nachrichten 7: 55–59.

Tartally A, Varga Z. 2008. Host ant use of Maculinea teleiusin the Carpathian Basin (Lepidoptera: Lycaenidae). ActaZoologica Academiae Scientiarium Hungaricae 54: 257–268.

Thomas JA. 1980. Why did the large blue become extinct inBritain? Oryx 15: 243–247.

Thomas JA, Elmes GW. 1998. Higher productivity at thecost of increased host-specificity when Maculinea butterflylarvae exploit ant colonies through trophallaxis rather thanby predation. Ecological Entomology 23: 457–464.

Thomas JA, Elmes GW, Clarke RT, Kim KG, MunguiraML, Hochberg ME. 1997. Field evidence and modelpredictions of butterfly-mediated apparent competitionbetween gentian plants and red ants. Acta Oecologica 18:671–684.

Thomas JA, Elmes GW, Wardlaw JC. 1993. Contest com-petition among Maculinea rebeli butterfly larvae in antnests. Ecological Entomology 18: 73–76.

Thomas JA, Elmes GW, Wardlaw JC. 1998. Polymorphicgrowth in larvae of the butterfly Maculinea rebeli, a socialparasite of Myrmica ant colonies. Proceedings of the RoyalSociety of London Series B, Biological Sciences 265: 1895–1901.

Thomas JA, Elmes GW, Wardlaw JC, Woyciechowski M.1989. Host specificity among Maculinea butterflies inMyrmica ant nests. Oecologia 79: 452–457.

Thomas JA, Schönrogge K, Elmes GW. 2005. Specializa-tion and host associations of social parasites of ants. In:Fellowes MDE, Holloway GJ, Rolff J, eds. Insect evolution-ary ecology. Wallingford: CABI Publishing, 475–514.

Thomas JA, Simcox DJ, Clarke RT. 2009. Successful con-servation of a threatened Maculinea butterflies. Science325: 80–83.

Thomas JA, Wardlaw JC. 1992. The capacity of a Myrmicaant nest to support a predacious species of Maculinea rebeliinhabitants in ant nests. Oecologia 91: 101–109.

Thompson JN. 1999. Specific hypotheses on the geographicmosaic of coevolution. American Naturalist 153: 1–14.

Van Langevelde F, Wynhoff I. 2009. What limits the spreadof two congeneric butterfly species after their reintroduc-tion: quality or spatial arrangement of habitat? AnimalConservation 12: 540–548.

Witek M, Sliwinska EB, Skórka P, Nowicki P, WantuchM, Vrabec V, Settele J, Woyciechowski M. 2008. Hostant specificity of large blue butterflies Phengaris (Macu-linea) (Lepidoptera: Lycaenidae) inhabiting humid grass-land in East-central Europe. European Journal ofEntomology 105: 871–877.

Witek M, Canterino S, Balletto E, Bonelli S. 2012. Lifecycle and growth pattern of the endangered myrmecophil-ous Microdon myrmicae (Diptera: Syrphidae). EuropeanJournal of Entomology 109: 457–461.

Witek M, Nowicki P, Sliwinska BE, Skórka P, Settele J,Schönrogge K, Woyciechowski M. 2010. Local host antspecificity of Phengaris (Maculinea) teleius butterfly, anobligatory social parasite of Myrmica ants. Ecological Ento-mology 35: 557–564.

Witek M, Skórka P, Sliwinska BE, Nowicki P, Moron D,Settele J, Woyciechowski M. 2011. Development of para-sitic Maculinea teleius (Lepidoptera: Lycaenidae) larvae inlaboratory nests of four Myrmica ant host species. InsectesSociaux 58: 403–411.

Witek M, Sliwinska E, Skorka P, Nowicki P, Settele J,Woyciechowski M. 2006. Polymorphic growth in larvae ofMaculinea butterflies, as an example of biennialism inmyrmecophilous insects. Oecologia 148: 729–733.

Woyciechowski M, Slowik J, Muehlenberg M. 2006.Hosts of the butterfly Maculinea teleius among Myrmicaants in northern Mongolia. Sociobiology 48: 493–502.

Zakšek V, Malacic K, Rebeušek F, Verovnik R. 2005.Distribution and autoecology of Maculinea teleius and M.nausithous (Lepidoptera: Lycaenidae) in Northeast Slov-enia. In: Settele J, Kühn E, Thomas JA, eds. Studies on theecology and conservation of butterflies in Europe, Vol. 2.Species ecology along a European gradient: Maculinea but-terflies as a model. Sofia-Moscow: Pensoft Publishers, 253–256.

SUPPORTING INFORMATION

Additional Supporting Information may be found in the online version of this article at the publisher’s web-site:

Table S1. General information on Myrmica host ants exploited by social parasites at five populations. tel,Maculinea teleius; nau, Maculinea nausithous; alc, Maculinea alcon; mic, Microdon myrmicae; double, numberof nests with double infestations (parasite associations are shown in parenthesis). Numbers of single parasiteinfestations include colonies with double infestation. The symbol ‘x’ means that parasite was not present at thesite, whereas ‘0’ that it was present but the larvae were not found.

CO-OCCURRING SOCIAL PARASITES OF ANTS 709

© 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 699–709