Effect of Host Plant on Parasitism of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) by Hyposoter didymator Thunberg (Hymenoptera: Ichneumonidae) and Cotesia kazak (Telenga) (Hymenoptera: Braconidae)

Abstract

The effect of host plant on parasitism of second-instar Helicoverpa armigera by two introduced larval parasitoids, Hyposoter didymator and Cotesia kazak, was investigated in glasshouse experiments. Parasitism was lowest on chickpea (5.4% for H. didymator and 11.8% for C. kazak). Higher levels of parasitism (50.1-85.0% for H. didymator and 25.7-55.3% for C. kazak) were recorded on sorghum, sunflower, cotton, soybean and pigeonpea. This suggests that the parasitoids should be released against Helicoverpa spp. infestations on the major summer crops—sorghum, sunflower, cotton and soybean—rather than against the first spring generation infesting chickpea. Sorghum and sunflower are preferred release crops because parasitism levels are high and disruption by insecticide sprays is less likely.