Diversity of Diurnal Insect Pollinators in Mustard (Brassica juncea) Agro-ecosystems

Abstract

Pollinator diversity enhances ecosystem resilience and ensures stable pollination under varying environmental conditions. A field study was conducted to assess the diversity and community structure of diurnal insect pollinators associated with mustard (Brassica juncea). Pollinators were recorded through quadrate observations, sweep netting and visual counts during the flowering period. Five insect orders were recorded during the study, among which Hymenoptera exhibited the highest species richness (16 species), followed by Diptera (11 species) and Lepidoptera (10 species). Hymenoptera also showed the highest diversity with a Shannon–Wiener diversity index (H′) of 2.30 and Simpson’s diversity index of 8.02, along with comparatively lower dominance (Berger–Parker dominance index = 0.19). Diptera and Lepidoptera also recorded relatively high diversity and evenness, indicating a balanced representation of species within these orders. In contrast, Coleoptera and Hemiptera were comparatively species-poor with lower species richness; however, these groups exhibited relatively higher evenness values, indicated a more uniform distribution of individuals among the limited number of species present. The study highlights the ecological significance of diverse diurnal insect pollinators in mustard agro-ecosystems and supports the need for their conservation to sustain pollination services.