author(s)
M Sonowal Bora, MK Deka and SS Bora

abstract
A study was carried out on foraging behaviour of Eristalinus and Syrphini in respect to foraging activity, foraging rate, foraging speed, loose pollen grains and abundance in Assam Agricultural University, Jorhat during 2017-2018 and 2018- 2019 on pollination of rapeseed flower var. TS-38. The results revealed that the maximum number of flower visit by Eristalinus and Syrphini were made during 1000-1300 hours and 1100-1200 hours whereas minimum activity at 1500-1600 hours and 0700-0800 hours of the day respectively. Relative abundance of Eristalinus and Syrphini was recorded to be maximum at 1100-1200 and 1000-1300 hours of the day. The number of loose pollen grain adhering to the bodies of Eristalinus and Syrphini was recorded to be 1418.2 ± 44.19 and 1268.4 ± 60.33 in 2017-18 and during 2018-19 were 1333.2 ± 50.48 and 1294.6 ± 65.10 per forager. The maximum pollination index of 8.01 was recorded from Syrphini as compared to 7.20 Eristalinus in 2017-18 and during 2018-19 were recorded 7.40 from Eristalinus as compared to 7.21 of Syrphini on rapeseed. The present study revealed that Eristalinus and Syrphini made more visit during midday as compared to morning and evening with more activity, foraging rate and foraging speed to rapeseed flowers bloom whereas number of loose pollen grain adhered to body of Eristalinus was more compared to Syrphini.