Comparative foraging behaviour and pollination efficiency of Apis laboriosa S. and Apis cerana F. on black mustard (Brassica nigra L.) in Western Himalaya, India

Crop productivity profoundly depends upon efficient pollination. Pollinator diversity and foraging behaviour patterns of pollinators ensure efficient pollination. Therefore, we conducted an observational study on the diversity of insect pollinators of black mustard (Brassica nigra). We also compared the pollination efficiency of its two primary pollinators, i.e. Apis dorsata laboriosa and Apis cerana indica. The study was conducted in Uttarakhand, India, during the peak flowering season (February and March). The flower visitation rate of A. cerana (9.87 ± 2.45 flowers/min) was significantly higher (P < 0.0001) than that of A. laboriosa (7.52 ± 2.08 flowers/min). Time spent per flower and time spent per flight were higher for A. laboriosa than A. cerana. Also, A. cerana started its diurnal activity earlier (08:00 h) and ceased later (17:30 h) compared to A. laboriosa (09:00 h and 17:00 h respectively). A brief decline was observed in the activity of A. cerana during the peak activity of A. laboriosa. This is possibly due to asymmetric interspecific competition, which might lead A. cerana to shift its peak activity earlier (11:30 to 12:00 h) than A. laboriosa (13:00–13:30 h). The pollen load and area of corbiculae of A. laboriosa were more than that of A. cerana. Our results suggest that A. cerana is a more efficient pollinator of black mustard than A. laboriosa.