Rural–Urban Differences in Odonata Diversity and Population Dynamics across Agricultural Landscapes of the Eastern Gangetic Plains

Abstract

Odonates are sensitive indicators of ecological condition because their life cycle depends on the integrity of both aquatic and terrestrial habitats. Here, we compared odonate diversity, assemblage composition and seasonal population dynamics across rural and urban agricultural landscapes in the Eastern Gangetic Plains. Weekly visual surveys of adult odonates were conducted from March 2022 to February 2024 in the agricultural areas of Manpur (rural) and Gaya city (urban), spanning fields of food grains, vegetables, pulses and oilseeds. Community structure was analysed using relative abundance, species richness, Shannon diversity, evenness, dominance, Sørensen similarity, one-way ANOVA and principal component analysis. The rural landscape supported 24 species, compared with 17 in the urban landscape, and the two assemblages showed only moderate similarity (SSI = 0.571). Food-grain fields showed the strongest association with odonate community structure and had the highest richness (S = 21), abundance (N = 2239) and Shannon diversity (H′ = 2.734). Seasonal effects were significant in both landscapes, with abundance peaking during the monsoon; this seasonal dependence was slightly stronger in the urban landscape (ICC = 0.426) than in the rural landscape (ICC = 0.368). These findings show that habitat heterogeneity, crop mosaics and monsoon-linked aquatic microhabitats are key determinants of odonate persistence in agricultural landscapes of the Gaya region.