Diversity of Hymenopteran Parasitoids in different Crop Ecosystems

Abstract

Surveys were carried out in different districts viz., Shivamogga, Davangere and Chitradurga of Karnataka to collect and document hymenopteran parasitoids parasitizing insect pests attacking different crop ecosystems. A total of 42 hymenopteran parasitoids species represented by 33 genera belonged 12 families were documented from a collection of 1379 specimens from different stages viz., egg, larva, pupa and adult stage of host insects from different host plants viz., rice, maize, cabbage, cotton, coconut, brinjal, cashew, crape jasmine, tobacco, field bean, soybean, arecanut, cocoa, okra and pongamia. Among them, maximum parasitoids species (20) were collected from larval stage of host insects with per cent species composition of 47.62. Among the families, Braconidae was found most dominant (comprised of 23.81%), followed by Eulophidae (16.67%), Encyrtidae and Scelionidae (each with 14.29%). Alpha and beta diversity were computed for the three zones. Species diversity in terms of richness, evenness and abundance of hymenopteran parasitoids were calculated and compared during study period using Shannon-Wiener index, Simpson diversity index, Margalef’s diversity index, Menhinick’s index and Evenness. Species diversity was high in Shivamogga district as evidenced by Shannon-Wiener index (2.49), Simpson diversity index (0.88), Margalef’s index (4.09) and Menhinick’s index (1.22) and Evenness (0.46), followed by Davanagere district with respect to Shannon-Wiener index (1.69) Simpson’s diversity index (0.75), Margalef’s index and Menhinick’s index (2.27 and 0.90), respectively, while evenness was 0.24 and Chitradurga district with respect to Shannon-Wiener index (1.34) Simpson’s diversity index (0.54), Margalef’s index and Menhinick’s index (2.12 and 0.59), respectively.