Vol. 4, Issue 3 (2019)
Parasitism potential of Diadegma insulare (Cameron) (Ichneumonidae: Hymenoptera) against Plutella xylostella (L.) (Plutellidae: Lepidoptera)
Author(s): AM Bhosale, VA Bhosale
Abstract: Diadegma insulare(Cameron) (Ichneumonidae: Hymenoptera) is a solitary larval parasitoid of Plutella xylostella (L.) (Plutellidae: Lepidoptera), a notorious and polyphagous pest of cabbage and cauliflower in India. Nutritional requirement, host age, specificity and density dependent factor play a very crucial role in biocontrol program of parasitoids and further their release in the field for pest control strategies. Attempt has been made to initiate their mass multiplication for successful biocontrol programme. Therefore, present work was conducted to find out the optimum host stage and density for maximum progeny production of the parasitoid under laboratory conditions. 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. insularewas 20, which generate maximum parasitism (41.00%). Host specificity by exposing the parasitoids towards different host species and analyse parasitoid preference by P. xylostella > Spodoptera litura (Fabricius) > Mythimna separate 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. insulare fed with 50% honey solution, exposed to 3-5 day old caterpillars of P. xylostella at density of 20 gave maximum progeny production and effectively utilized in the biocontrol programme.
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