Population assemblage of the small fruit flies (Diptera, Drosophilidae) in the North Western Ghats of Karnataka (India) with special report on the dominant species

The population assemblage of Drosophilidae in the four districts of North Western Ghats was analysed. A total of 13,604 individuals comprising 17 species collected from 8 localities during the period of 2021–22 across various seasons. The study highlights the dominance of three species (Drosophila bipectinata Duda, D. malerkotliana Parshad & Paika and D. eugracilis Bock & Wheeler) belonging to ananassae and eugracilis subgroups. Overall collection data revealed the highest species richness and diversity for Dharwad and UK interior forests, whereas the maximum abundance and the highest evenness were observed in UK coastal and Belagavi forests respectively. The species rank-abundance curve revealed Dharwad forest had higher species richness and comparatively stable species assemblage. Drosophila eugracilis was the dominant species in localities of Dharwad and Belagavi forests, whereas D. bipectinata was the dominant species in both coastal and interior localities of UK forests. Rare faction curves plotted across the different seasons for all the forest localities revealed population assemblage and species richness of all forests across different seasons. Morisita index of similarities showed similarities for populations across localities and seasons. Nonparametric independent sample Kruskal-Wallis test was done to test distribution of abundance of individual species across spatial and temporal groups. The study reveals variation of population assemblage across the forests of Dharwad, Belagavi, and Uttara Kannada (coastal and interior) and dominance of D. bipectinata, D. malerkotliana and D. eugracilis.