International Journal of Environment and Climate Change

The current study records the diversity of Drosophila species during the transitional phase from late winter to early pre-monsoon (March–May) in the campus of Sikkim Alpine University and the surrounding Kamrang area of South Sikkim, India. Six different microhabitats were sampled twice a week using triplicate bait traps containing fermented fruits, and the collected flies were identified using standard taxonomic keys and morphological analysis. Simpson’s, Shannon’s, and Berger–Parker indices were calculated to assess diversity patterns, and climatic parameters—including temperature, rainfall, wind speed, and cloud cover—were analyzed for their correlation with species distribution.

A total of seven species comprising 526 individuals were identified. Drosophila immigrans (209 individuals) and Drosophila busckii (182 individuals) were the most dominant, particularly during April, when diversity peaked (Shannon H′ = 1.29; Simpson 1–D = 0.69) with seven species recorded. March exhibited the lowest richness (3 species; H′ = 0.93), while May recorded intermediate richness (5 species; H′ = 1.34). Correlation analysis revealed significant climatic associations, especially for Drosophila busckii, which showed strong positive relationships with temperature (r = 0.526, p < 0.01) and wind speed (r = 0.560, p < 0.01), but negative correlations with rainfall and cloud cover.

The findings provide the first baseline account of Drosophila diversity in South Sikkim and demonstrate how short-term climatic variability shapes community composition in subtropical montane habitats. This study highlights the ecological significance of Drosophila as bioindicators and underscores their potential role in long-term biodiversity monitoring and conservation planning in the Eastern Himalayas.