Species Composition and Conservation Risk Factors for Bumblebees (Bombus spp.) Across the Chitwan Annapurna Landscape, Nepal

The study was conducted in Chitwan Annapurna Landscape(CHAL) to explore the species composition of bumblebee (Bombus spp.) and their conservation risk factors along elevation gradients. The field surveys were conducted in a range of different habitats along an altitudinal gradient (500 to 3500 m asl) in the Kaligandaki, Marsyangdi, and Budhigandaki river basins of study area. A total of 656 Bombus specimens were identified comprising 16 different species with eight new records (Bombus grahami, B. pressus, B. branickii, B. cornutus, B. novus, B. turneri, B. lepidus, and B. asiaticus ) from this region. The highest relative abundance was of B haemorrhoidalis followed by B. festivus. The major survival risks factors for bumblebee were habitat loss, ecosystem alternation by invasive plants, pesticide application and nesting sites destruction by many human activities. The severity of conservation risk factors varies along elevation gradient that determine on species filtering of bumblebee along the CHAL.