Foraging Behaviour of Some Syrphid Flies on Mango

Abstract

This study in on the foraging behaviour of syrphid flies belonging to the tribes Eristalini (Eristalinus arvorum, E. quinquestriatus and Mesembrius quadrivittatus) and Syrphini (Episyrphus balteatus). The foraging activity, rate and speed, loose pollen grains and abundance were evaluated at Jorhat during 2018 and 2019 on mango flowers var. Amrapali. These revealed that the peak period of visit was 1 000-1200 hr. The relative abundance of the syrphids was maximum (8.90 ± 0.22/5 min) at 1100-1200 hr and (7.07 ± 0.51/5 min) at 1200-1300 hr; it was minimum (2.40 ± 0.17 and 2.49 ± 0.09/5min) at 0700-0800 hr, respectively. The loose pollen grains adhering to them ranged from 1294.80 ± 60.82 to 1415.80 ± 110.80/forager. The maximum pollination index of 12.52 was obtained with the Eristalini, while it was 8.14 in Syrphini (2018); in 2019, it was 9.63 and 7.14, respectively. These syrphids visited flowers during midday with more activity, foraging rate and foraging speed.