Study of foraging behaviour of syrphids viz. Episyrphus balteatus (De Geer) and Eupeodes frequens (Matsmura) (Diptera: Syrphidae)onmustard bloom (Brassica juncea L.: Cruciferae) under mid hill conditions
The present study was carried out in the Farm of Department of Entomology, UHF Nauni, Solan (India) on Indian mustad (Brassica juncea L.). Hoverflies are important pollinators and play an important role in cross pollination in mustard. To determine the pollination efficiency of syrphids viz.Episyrphus balteatus (De Geer) and Eupeodes frequency (Matsmura), different parameters viz. foraging rate, foraging speed, relative abundance and loose pollen grains adhering to the body of forager were recorded under open field conditions on Indian mustard bloom (Brassica juncea L.). Foraging rate, foraging speed, relative abundance loose pollen grains was recorded as 8.26 flowers/min, 6.45 sec/flower, 5.21 syrphids/ m2/5min and 475.60 pollens per forager, respectively for E. balteatus and these for E. frequens was 11.20 flower/min, 4.68 sec/flower, 3.51 syrphids/m2/5min and 305.40 pollens/forager, respectively. E. balteatus showed a higher pollination index (6.93) than E. frequens (5.83), hence, E. balteatus ranked higher than E. frequens in study of comparative pollination efficiency.