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ABSTRACT

During 2008-09, six bio-pesticides were evaluated, under field conditions, for their efficacy against major defoliators and capitulum borer, Helicoverpa armigera Hub. infesting sunflower, at the Zonal Agricultural Research Station, UAS, Bangalore. All the six bio-pesticides viz., Spodoptera NPV @ 2x108 POB/ml, Helicoverpa NPV @ 2x108 POB/ml, Pongamia Seed Kernel Extract @ 5%, Neem gold 0.03EC(300ppm)(0.5%), Neem Seed Kernel Extract @ 5 % and Prosopan @ 10ml/L. were on par with the insecticidal checks (endosulphan 35 EC @ 0.07% and profenophos 50EC @ 0.05 %) and they were found to be significantly superior than untreated check in the suppression of defoliators, 50 days after sowing. Neem seed kernal extract, (5%), prosopan (10 ml/lit) and both the insecticides were significantly superior than the other treatments, at one day after the second spray (i.e., @ 90 DAS) for H.armigera supression.

Key words: Helicoverpa armigera, crop pest, biopesticides, sunflower

INTRODUCTION

Among the biotic stress factors, insect pests and diseases are the major production constraints in sunflower production. As many as 251 insect and acarine species have been recorded on sunflower at the global level (Rajamohan, 1976). In India, sunflower crop is damaged by different species of insect pests, of which the polyphagous pests like capitulum borer (Helicoverpa armigera Hubner), green semilooper (Thysanoplusia orichalcea Fab.), Bihar hairy caterpillar (Spilarctia obliqua Walker), tobacco caterpillar, Spodoptera litura Fab., cabbage semilooper (Trichoplusia ni Hubner), cutworm (Agrotis spp.) and leafhopper (Amrasca biguttula biguttula Ishida) are of major economic importance (Basappa, 1995).

Crop loss due to insect pests in sunflower varies from region to region. As a result of severity of grasshopper and other seedling pests, the plant stand of sunflower crop could be reduced by more than 30 per cent (Basappa and Bhat, 1998). The loss in seed yield due to defoliators in a rainfed kharif crop was up to 268 kg per ha at Bangalore (Anon., 1976; Panchabhavi and Krishnamoorthy,1978). Similarly, Banerjee and Haque (1984) estimated yield losses up to 40 per cent due to Diacrisia casignetum Kollar. The capitulum borer, H. armigera is highly polyphagous, with about 181 host plants including important crop plants such as pulses, cotton, vegetables etc. (Manjunath et al., 1985). The pests like gram caterpillar H. armigera and tobacco caterpillar (S. litura ) in sunflower...

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