Strategies for the management of Calopepla leayana on Gmelina arborea

S. Singh, A. Kumar, N. Senthilkumar, and A.N. Singh Rain Forest Research Institute, Jorhat – 785 001, Assam (INDIA)

Introduction Gmelina arborea (Roxb.) an important member of the family Verbenaceae, is a commercially important fast growing deciduous tree species. It is widely distributed through out the greater part of India, Nepal, Bhutan, Bangladesh, Burma, Sri Lanka and Philippines. In India, G. arborea is found in eastern sub-Himalayan tract, indo-gangetic plains, Aravalli Hills, central India, western peninsula and western Himalayas. It is grown extensively in entire northeastern India, and grows well in wide range of temperature and rainfall. It prefers fertile alluvial and well-drained soils, but hardly grows in heavy clay soils and remains stunted in dry, sandy and poor soils.

G. arborea is considered to be one of the most reliable medium to large timber

tree found in India, and wood of the species falls in the category of extremely durable timbers with long life when exposed, and needs no preservatives. The wood of this species is an excellent source for pulp and paper industries as vessels and fiber configurations are most suitable for pulping (Redko, 1983). It has also a distinguished acceptability as fodder and medicinal plant, and used in treatment of various diseases like gonorrhea, catarrh of bladder and cough. Gmelina grows rapidly and can be harvested under short rotations. The forecasts indicate that there could be 8,00,000 Gmelina plantations both in tropics and subtropics by 2020 (Dovrak, 2003).

In India and particularly in northeast, it is grown extensively both in

government and private lands, and has substantially been contributing in timber, fodder and industrial wood. However, low productivity, poor bole form and susceptibility to various insect-pests and diseases are some of the reasons for its non deployment at commercial scale.

Although G. arborea suffers multifarious insect injuries by a complex of

insect pests including 21 defoliators and 13 shoot borers, Calopepla leayana is the most destructive defoliator (Mathur and Singh, 1960). It is known to destroy more than 2000 acres of young plantations in a single year in India (Mathur and Singh, 1960; Browne, 1968). It has been reported that trees remain leafless for almost half the period of the growing season due to defoliation by this pest. In northeastern India, monoculture of G arborea has been abandoned in past because of this insect (Ahamed, 1982). The beetle feeds by cutting circular holes on dorsal side of the leaves, and gnawing young buds and developing shoots. The pest is active from March/April to November/December in NE region. The trees are defoliated

Indian Forester 132 (5):581-588, 2006

completely two times in this region – once during May/June and secondly in August/September.

Earlier insecticides were thought to be panacea for an insect attack, and used

indiscriminately. The deleterious effects of insecticides on the environment had limited their use, especially in forestry. Hence, application of cultural, physical and biological control measures of insect pest is safe in plantations and nurseries. In India, a number of studies have been carried out on the biological control of insect pests in forestry. Possible biocontrol agents of Calopepla leayana have explored and presented in Table 1. Researchers of RFRI have conducted number of experiments on the biological control of Calopepla leayana on Gmelina arborea under laboratory conditions (Table 2). However, nothing has been reported on field applications. The present paper aims at providing a technology package model of practices for eco-friendly strategies for the management of C. leayana on G. arborea. Brief review of the status of research on the subject

A complex of insect pests –21 leaf defoliators, 13 shoot borers and many other species belonging to orders Coleoptera, Lepidoptera, Homoptera, and others attack G. arborea (Mathur and Singh, 1960). Of them, C. leayana is the most serious one (Ahamed and Sen Sharma, 1990). Gupta et al., (1989) evaluated the relative toxicity of 22 conventional pesticides against C. leayana on G. arborea, and proved that formothion, monocrotophos, quinolphos and chlordimeform were highly toxic to the adults. Singh et al. (1999) reported an exhaustive account on the bioecology of a promising biocontrol agent namely Brachymeria excarinata (Hymenoptera: Chalcidae) and found that wasp might has an immense biocontrol potential in managing the dreaded beetle. Entomopathogenic fungi viz., Beauveria bassiana and Metarhizium anisopliae were found to be significantly pathogenic to all the larval as well as adult stages of C. leayana. The fungi cause white and green muscardine diseases to the larvae and adults respectively (Singh et al. 2002). Neem seed kernal extract (Neemazal –F) was very effective against I-V instar larval stages of C. leayana. It was also reported that – 0.007% of Neemazal –F was used for 50% of mortality during July – August (Borthakur, 2001). Though all these experiments indicate effective control of Calopepla leayana, have limited to laboratory conditions and nothing is known about the field applications. In addition, host resistance is a valuable tool in pest management and varieties that are inherently less infested by insects than other varieties under comparable environmental conditions may be considered resistant. Efforts need to be direct towards search resistance genotypes. Researchers should identify such trees and bring it to the notice of tree breeders for further propagation and breeding. In an earlier experiment at RFRI on screening of insect resistance clones of G. arborea indicated that 16.1 percent of the total 70 clones selected were highly resistant to C. leayana (Singh et al., 2003). It has also been found that the clones with more hairs/unit area are least preferred by C. leayana. Only those clones should be recommended for propagation.

Importance of the study

G. arborea though is an important fast growing timber species, has greatly eclipsed by serious and repetitive defoliation by C. leayana. In the past it was only due to the fear of this pest that mass plantation of the species had been abandoned or limited only few patches under afforestation. Various management strategies were recommended by different researchers under laboratory. However, nothing is known about the field applications. So the main aim of the proposed project is to develop a package of management practices of G. arborea with special reference to C. leayana. Model package has reported in the form of a flow chart (Flow chart 1). Once developed, it will be feasible for farmers, private and government planters and industries to grow G. arborea as a large scale for industrial and timber purposes with ensured higher productivity. Various stages of methodology are here under discussed in brief.

(i) Rearing of Calopepla leayana

Calopepla leayana need to be reared on the large scale in the laboratory for

the mass multiplication of its natural enemies. For maintaining the laboratory culture of C. leayana adults and eggs to be collected from the respective field stations and reared in the laboratory at room temperature 28±2°C and 70-80% RH. The adults to be reared in round bottom glass Jars (20.5cm in height and 15.5cm in diameter). Mouth of each jar to be covered with muslin cloth with the help of a rubber band. Fresh leaves of G. arborea need to be provided to the larvae after every 24 hrs. (ii) Mass multiplication of Brachymeria excarinata.

B. excarinata should be cultured in the laboratory on the pupae of C. leayana. Singh et al. (2002) reported that this parasitoid could be of immense biocontrol potential agent of C. leayana, and thus should be mass reared in the laboratory and released in the months of April/May and also during August/September when the pupae of first and third generation appear in this region. Field collected III instar larvae of C. leayana to be reared in the laboratory in a fine wire net cabinet. The parasitoids to be procured from the laboratory reared infected pupae collected from field. The parasitoids to be provided to the 48hrs. old mated B. excarinata female for oviposition. Each pupae in which B. excarinata female oviposited should be removed and kept in 5cm size petridish. Adults are to be emerged after 11-13 days and are to be allowed to mate. 48hrs old B.excarinata mated females are to be released into the field as detailed in Flow chart 2. (iii) Mass culture of fungal pathogens

The fungal pathogens viz., B. bassiana and Metarhzium anisopliae should be isolated from the diseased larvae collected from the field. It is suggested to be cultured on Potato Dextrose Agar (PDA) medium and incubated at 26-27º C for 6-8days in the dark. Spores to be harvested in 0.1% Tween – 80 solution in double distilled water and the pure culture to be stored in double distilled and sterilized water in capped 30 ml vials at 4º C for future use. Concentration of spores/ml in the stock solution to be determined by haemocytometer method. 1X107 spores/ml of spores suspension of B. bassiana Metarhzium anisopliae to be prepared and sprayed to I to VI instars larvae and adults as recommended by Singh et al. (2002). The larval and adult mortality to be observed continuously after spraying. The dead insects are to be kept in petriplates lined with moist blotting paper for sporulation of the infecting fungi. The cause of the death should be confirmed by examining the cadavers for spores and associated mycelia of concerned pathogen under a phase contrast microscope. The mortality data could subject to further statistical analysis as suggested in flow chart 3. (iv) Botanical insecticides Neem seed kernal extract (Neemazal –F) – 0.007% can also be used for 50% of mortality during July – August followed by the method of Borthakur (2001) (v) Screening of resistant genotype

It is important technique to screen the resistance genotypes showing promise in the afforestation programmes. These genotypes need to be carefully observed for the incidence of C. leayana. Defoliation intensity to be rated visually by comparing the occurrence of attacked and uninfested leaves in all the individuals of the genotype for a period of three years. The intensity will be classified into 3 main classes based on a modified Wellendorf (1989) health score for trees and compare with Rohrmoser severity scale (Mac Dicken et al., 1991).

A range of productive clones needs to be selected for feeding experiments

under controlled conditions. Among the selected clones few clones could finally be taken for further observations. Fresh cut leaves of clones to be provided for equal aged larvae and adults of C. leayana for feeding for a period of 24 hrs. Area fed on each clone to be calculated carefully. Physical properties of leaves such as trichomes, silica content, and thickness of leaves are to be analysed. Biochemical estimation of clone leaves should be done for total protein (Lowery et al, 1951), carbohydrates (Dubois et al., 1958) and lipids (Floch et al., 1957). For detection of phenols, flavinoids and anthocyanidins, the method of Harbone (1973) could be adopted as detailed in flow chart 4. (vi) Field application of biological control agents

Biological control agents could applied to the field as per the recommendations of previous workers at RFRI as presented in table 2. B. excarinata, a pupal parasitoid should be released in the field as per the following recommendation. One fertile female should be released when the population is 57-76 pupae per tree. The two successive release once during the months of May - June when first generation pupae start appearing in the field and the second during August to September should be made when the pupae of third generation appear. The last release will be detrimental to the over wintering population. Observations should be made to evaluate the impact of B. excarinata on population reduction of C. leayana in the field. Entomopathogenic fungi namely, M. anisopliae and B. bassiana Spore suspension at the concentration of 1x107 spores/ml should be sprayed if population is about 20 individuals of I-V instar larvae and adults per tree. The freshly prepared spore suspension will be very effective on adults and release in the field. Rainy season is suitable for field application of fungal spores when temperature and humidity conditions are optimum for pathogenesis. The mortality of larvae and adults should be observed only upto 10 days after application and confirm the cause of death due to fungal attack. Commercially available neem seed kernel extract (Neemazal – F) should be prepared at the concentration of 0.007% and sprayed in the field for 50% mortality. Economics of management

The proposed management protocol is an efficient, economic and an ecofriendly approach for farmers, traders and researchers. References Ahamed, S.I. 1982. Studies on morphology, bionomics, ecology and digestive

physiology of Calopepla leayana Latr. (Chrysomelidae:Coleoptera) Ph.D thesis.

Ahamed, S.I. and Sen Sharma, P.K. 1990. Bionomics of Calopepla leayana Latr. A serious defoliator of Gmelina arborea plantations in India. Indian Forester. 116 (1): 71-82.

Brown, F.G. 1968. Pest and diseases of forest plantation trees. 1330 pp Clarendon press. Oxford.

Dev, A.C. and Ramaswamy, R. 1960. Indian woods used for match manufacture, Indi. For. Bull. 203 (NS) Minor Forest Products. Manager of Publication. New Delhi.

Dovrak, W.S. 2003. World view of Gmelina arborea : Opportunities and challenges. In: Recent advances with Gmelina arborea (eds> W.S. Dovrak, G.R.

Hodge, W.C. Woodbridge & J.L. Romero) CD .Rom CAMCORE, NC State University, Raleigh, NC, USA.

Dubois, M., Gilles, K.A., hamilton, J.K., Rebers, P.A., and Smith, F. 1958. Colorimetric determination of sugars and related substances. Anal. Chem., 28: 351-356.

Folch, J., Lees, M., and Sloane-Stanley, G.H. 1957. A simple method for the isolation and purification of total lipids from animal tissues. J. Biol. Chem., 226: 497-506.

Gupta, B. K. Ahamad, S.I. and Veer, V. 1989. Relative toxicity of some conventional insecticides against adult beetles of Calopepla leayana. Ind. For. 115: 430-434.

Harbone, J.B. 1973. Phytochemical methods. A guide to modern techniques of plant analysis. Chapman and Hall. London.

Mac Dicken, K.G., Wolf, G.V., and Briscoe, C.B. (Editor). 1991. Standard research methods for multipurpose trees and shrubs. Windrock international Institute for Agricultural development.

Lowry, O.H., Rosebrough, N.J., Farr, A.L., and Randall, R.J. 1951. Protein measurements with Folin phenol reagent. J. Biol. Chem., 193: 265-275.

Mathur, R.N. and Singh, B. 1960. A list of insect pests of forest insects of India and neighbouring countries. Forest Bulletin. Dehradun (N.S.) (Ent.) No.171 Part 1: 1-165.

Borthakur, N. D. 2001. Potentiality of neem seed kernal extract in the management of Calopepla leayana Latr. (Coleoptera :Chrysomelidae) A major pest of Gmelina arborea Roxb. Ph. D thesis, FRI Deemed University, Dehradun

Redko, B.V.P. 1983. Vessels of hardwoods: Eucalyptus deglupta, E. urophylla and Gmelina arborea. ABCB 16th Annual meeting/3rd Latin American Cellulose and paper congress. Sav Paulo Brazil.

Singh, S., Deka, B., and Barthakur, N.D. 1999. Bioecology of Brachymeria excarinata (Hymenoptera:Chalacidae), A promising biological control agent of Calopepla leayana (Coleoptera:Chrysomelidae) A major pest of Gmelina arborea. Proceedings of workshop cum peer review on biological control of forest insect pest. FRI, Deharadun.

Singh, S., Barman, H.K. and BArthakur, N.D. 2002. Pathogenecity of Entomogeneous fungi on Calopepla leayana (Coleoptera:Chrysomelidae) A major insect pest of Gmelina arborea. Ann. For. 10 (2): 351-355.

Singh, S., Barman, H.K. and Deka, B. 2002. Integrated pest management In: Gmelina arborea: A technology mission (Eds.) Ashok Kumar et al., RFRI, Jorhat, Assam

Wellendrof, H. 1989. Possible gains from selection for resistance to needle cast in Norway spruce. The Arboretum, Horsholm.