author(s)
Navendu Nair, U Giri, T Bhattacharjee, B Thangjam, N Paul and MR Debnath

abstract
Field experiments were conducted to study the biodiversity of insect pest species infesting okra in Tripura during two seasons viz, summer (April to July, 2016) and winter (October, 2016 to January, 2017). A total of twenty eight insect pest species belonging to 6 orders were found to infest this crop. Maximum number of species were belonging to Hemiptera (12 nos.) followed by Lepidoptera (9 nos.) and Coleoptera (4 nos.). The Shannon and Wiener diversity index (H’) during summer and winter season for the insect pest complex of okra was calculated as 1.01 and 0.91, respectively. The Simpson’s diversity index (D) during summer and winter season was calculated as 0.14 and 0.19, respectively. These two indices for summer and winter season were more or less equal and exhibited a similar diversification. Similarly, Species Richness (7.31 and 7.49) and Species Evenness (0.71 and 0.64) during summer and winter season were more or less equal. However, by number the Leaf hopper (Amrasca biguttula biguttula ), Leaf beetle (Podagrica sp.), Blister beetle (Mylabris pustulata) and Leaf folder (Syllepte derogata) were more abundant in the field during summer season where as, Leaf hopper (Amrasca biguttula biguttula), Aphid (Aphis gossypii), White fly (Bemisia tabaci) and Leaf folder (Syllepte derogata) were more abundant during winter season. However, during Summer season Blister beetle (Mylabris pustulata), Leaf beetle (Podagrica sp.) and Red cotton bug (Dysdercus cingulatus) were found to be major pests causing considerable damage whereas, during winter season Shoot and fruit borer (Earias vittella) was found to be the major pest.