UTTAR PRADESH JOURNAL OF ZOOLOGY

Agriculture-based ecosystems support a rich diversity of insect fauna that play vital roles in maintaining ecological balance through pollination, decomposition, nutrient cycling and biological pest regulation. Understanding the composition and diversity of insect communities in crop ecosystems is therefore essential for conserving biodiversity and promoting sustainable agricultural production.

The present study examined the diversity, abundance and guild structure of insects associated with tomato agro-ecosystems in Kalyani and Islampur regions of the Lower Gangetic Alluvial Plains of West Bengal. Weekly observations recorded 1241 insect specimens belonging to 11 species under 6 orders, with Myzus persicae being the dominant species in both the locations. Diversity analysis revealed clear temporal variation in insect communities. In Kalyani, Simpson’s diversity index ranged from 0.3704 to 0.7907 during 2019–20 and 0.4625 to 0.7426 during 2020–21, while Shannon diversity values varied between 0.684 and 1.783. Margalef’s species richness reached a maximum of 2.025 (2019-’20) and 2.796 (2020-’21). In Islampur, Simpson’s index ranged from 0.4626 to 0.7704, indicating moderate diversity and richness throughout the study period. In case of spatial pattern, Kalyani exhibited comparatively higher diversity and evenness, whereas Islampur showed greater species richness. The abundance and diversity of predatory insects were considerably lower than those of pest species, and the pest guild became more stable over time while predator populations remained relatively unchanged. The findings indicate ecological dynamics in tomato fields under intensive chemical-based management, where reduced natural enemy diversity may weaken biological pest regulation. The study highlights the need for biodiversity-based pest management, habitat diversification and conservation of natural enemies to ensure sustainable tomato cultivation in the region.