Abstract
This study was conducted to understand the effect of abiotic factors on the foraging behavior of two native honeybee species (Apis dorsata and A. florea) andits ultimate impact on reproductive success of Brassica napus L. Foraging behavior of honeybees was studied in terms of visitation rate, visitation frequency, stay time on flower, stigma contact events, nectar robbing and pollen grain deposition on stigma. Simple linear regression model was used to find relationship between foraging behavior parameters and abiotic factors including ambient temperature, light intensity, wind speed and relative humidity. The results showed that A. dorsata had statistically higher visitation rate (54.23 +/- 1.307 flowers/ 300 seconds), number of stigma contact events (0.98 +/- 0.008) and pollen deposition (287.72 +/- 6.58 pollens) than A. florea i.e. 22.65 +/- 0.808 flower/300 seconds, 0.51 +/- 0.032 events and 154.83 +/- 7.83 pollens, respectively. The linear regression analysis showed that the stay time and nectar robbing of A. dorsata was not affected by any of the abiotic factors. Visitation frequency had negative relationship with all the abiotic factors. Stigma contact time decreased with the increase in temperature and increased with the increase in light intensity. In case of A. florea, stigma contact time had no relationship with any of the abiotic factor. Visitation rate and stay time were affected by light intensity. However, the value of R-2 did not exceed 0.25 in all these significant relationships. Nectar robbing events increased with the increase in relative humidity and decreased with the increase in wind speed. Apis dorsata was more efficient pollinator of B. napus than A. florea in terms of seed weight per pod and germination percentage.