Parasitism potential of Diadegma argenteopilosa (Cameron) (Hymenoptera : Ichneumonidae), an internal larval parasitoid of Spodoptera litura (Fab.) (Noctuidae: Lepidoptera)

Abstract

Diadegma argenteopilosa (Cameron) (Ichneumonidae: Hymenoptera) is an internal larval parasitoid of Spodoptera litura (Fab.) (Noctuidae: Lepidoptera), a notorious and polyphagus pest of pulses and vegetables in India. Attempt has been made to initiate their mass multiplication for successful biocontrol programme. Behavioral studies, food stuffs, host selection aspects plays a crucial role in mass multiplication of biocontrol agents. Therefore, present work was conducted to study the optimum host age, specificity and host density for maximum progeny production of the parasitoid under laboratory conditions and later their release in the field for the management of pest species. The parasitoid caused highest mortality in the pest larvae of second instars, 4 day old larvae were attacked most with high percent parasitism, 39.00%. Optimum density for maximum progeny production of D. argenteopilosa was 20, which generate maximum parasitism (43.00%). Host specificity by exposing the parasitoids towards different host species and analyse parasitoid preference by S. litura > Helicoverpa armigera (Hubner) > Mythimna separata Walker > Achaea janata (Linnaeus). Nutritional requirement of parasitoid was tested with different foodstuffs and found 50% honey best suited for maximum longevity 8.2 and 11.4 days for males and females respectively. The longevity ratio also female biased, 1: 1.39 (Male: Female). From the results it concludes that D. argenteopilosa fed with 50% honey solution, exposed to 3-5 day old caterpillars of S. litura at density of 20 gave maximum progeny production and effectively utilized in the biocontrol programme.