Vol.12_No.2 - Pesticide Alternatives Lab - Michigan State University

Spring 2003 Resistant Pest Management Newsletter Vol. 12, No.2greenhouse. Pest Management in Horticultural Ecosystems. 7 (1):54-58.Morse, J.G. and Brawner,O.L. 1986. Toxicity of pesticides of Scirtothripscitri and implications to resistance management. Journal ofEconomic Entomology. 79:560 570.Nair, V.V., Regunath and Visalakshi, A. 1991. Control of thripsScirtothrips dorsalis Hood on rose. Entomon, 16 (4): 327-329.Reddy, G.P.V., Deva Prasad, V. and Srinivasa Rao, R. 1992. Relativeresistance in chilli thrips, Scirtothrips dorsalis Hood populations inAndhra Pradesh to some conventional insecticides. Indian J. PlantProt. 20(2): 218 - 222.V. Sridhar and B. Jhansi RaniDivision of Entomology and NematologyIndian Institute of Horticultural ResearchHessaraghatta Lake Post, Bangalore-560 089IndiaStatus of Pyrethroid Resistance in Helicoverpa armigera in IndiaHelicoverpa armigera (Hubner) (Lepidoptera:Noctuidae) is charismatic and one of the most dreadedinsect pests in agriculture, accounting for theconsumption of over 30% of the total insecticide useworldwide. The frequent and rapid changes in croppingpatterns and agro-ecosystems, the polyphagus nature ofthe pest, and its cosmopolitan abundance haveaccentuated the problem globally. The problems of thispest are magnified due to its direct attack on fruitingstructures, its voracious feeding habits, its highmobility and fecundity, its multivoltine, overlappinggenerations with facultative diapause, its nocturnalbehaviour, migration, and host selection by learning,and a propensity for acquiring resistance againstinsecticides (Satpute and Sarode, 1995; Sarode, 1999).This pest has been recorded feeding on 182 plantspecies across 47 families in the Indian subcontinent,of which 56 are heavily damaged and 126 are rarelyaffected (Pawar et al., 1986). Losses due solely to thispest of up to Rs.10,000 million have been reported incrops like cotton, pigeonpea, chickpea, groundnut,sorghum, pearl millet, tomato, and other crops ofeconomic importance (Raheja, 1996).In India, Helicoverpa is represented by threespecies, with H. armigera constituting 99.2%, H.peltigera at 0.6%, and H. assulta at 0.2% of the totalpopulation (Pawar, 1998). In recent years, H. armigerahas assumed such serious proportions in the countrythat for the past decade, farmers and plant protectionagencies of central and state governments havevirtually become perplexed regarding its control whichultimately has lead to an array of social, economical,and political problems. Of these, a primary problemconcerns the development of resistance in this pest to anumber of insecticides including pyrethroids.Resistance to pyrethroids in H. armigera had beenreported from a number of countries through out theworld including India. The control failures of syntheticpyrethroids were first detected on pigeonpea against H.armigera at Lam farm, Guntur, A.P. in 1986. From1987-88 to 1989-90, continuous monitoring andevaluation of the H. armigera population revealed thatthe resistance levels were low during 1988-89 inAndhra Pradesh, decreased by a factor of 10 (Table 1).During the cotton season 1989-90, it increased nearly2-fold greater than that encountered in 1988-89. It mayalso be elucidated that the resistance response inNorthern India, i.e. the Delhi and Karnal strains,remained constant. It was also shown that theresistance was not restricted to one or the otherpyrethroid, but had extended to all the three pyrethroidsused in the country viz., cypermethrin, fenvelerate, anddeltamethrin (Mehrotra, 1991). The subsequent studiesconfirmed the major cause of crop failure in A.P. wasresistance to synthetic pyrethroids in this pest(Srivastava, 1995). Although, the pyrethroid resistancein H. armigera was found to be restricted to anapproximately 75km wide and 200km long beltcomprising three districts of A.P. viz. Prakasham,Guntur, and parts of Krishna (Dhingra et al., 1988), thepresence of increased tolerance to cypermethrin in thetwo strains collected in Tamil Nadu from cotton (1989)and groundnut (1991) suggested that resistance topyrethroids was wide spread and could be featuredthroughout South India (Armes et al., 1992). InCoimbatore, resistance to cypermethrin was found to64