Ecology, Diversity, and Seasonal Occurrence of Bombardier Beetles (Coleoptera: Carabidae: Brachininae) in Kolhapur District, Maharashtra

Bombardier beetles (Coleoptera: Carabidae: Brachininae) are ecologically significant ground-dwelling predatory insects known for their unique chemical defense mechanism and important role in maintaining soil ecosystem balance. Despite their ecological importance, systematic information on the diversity, habitat association, and seasonal occurrence of bombardier beetles from the Kolhapur district of Maharashtra, located in the northern Western Ghats biodiversity hotspot, is limited. The present study was undertaken to investigate the ecology, species diversity, and seasonal dynamics of bombardier beetles across different habitats of Kolhapur district. Field surveys were conducted in forest ecosystems, agricultural fields, grasslands, and riparian zones during pre-monsoon, monsoon, and post-monsoon seasons using pitfall traps, hand collection, and leaf-litter sampling techniques. Specimens were identified using standard taxonomic keys for the subfamily Brachininae. The study recorded moderate diversity of bombardier beetles, with dominant representation from the genera Brachinus and Pheropsophus. Species richness and abundance showed clear seasonal variation, with peak activity during the monsoon and post-monsoon periods, coinciding with favorable microclimatic conditions such as increased soil moisture and prey availability. Habitat-wise analysis revealed higher diversity in forest margins and low-intensity agricultural ecosystems compared to highly disturbed habitats, indicating sensitivity of bombardier beetles to environmental changes. Riparian habitats also supported notable beetle populations, emphasizing the importance of moisture-rich microhabitats. The present study provides baseline ecological data on bombardier beetles from Kolhapur district and highlights their potential as bioindicators of soil health and habitat quality. The findings contribute to future biodiversity assessments, ecological monitoring, and conservation planning in the Western Ghats region.