Flower-visiting insect pollinators of Brown Mustard, Brassica juncea (L.) Czern and Coss and their foraging behaviour under caged and open pollination

Honey bees are the primary pollinators of mustard crop because it is highly attractive to bees and provides both nectar and pollen. To analyze the diversity and foraging behavior of insect pollinators under caged and open pollination, different varieties/ lines (Kranti, Varuna, Marigold, Vardan, Vaibhav, EC399299, EC399301, EC399312 and EC399313) of Brassica juncea were planted during Rabi season 2010-2011 at Apiary Garden, G. B. Pant University of Agriculture and Technology, Pantnagar. It was revealed that 30 species of insect pollinators belonging to ten families under four orders visited mustard flowers. In open pollination, Trigona laeviceps had maximum average abundance (4.51 bees/m2/2 min) and foraging speed (18.55s) in Vardan and EC399313, respectively whereas Apis mellifera showed highest foraging rate (10.68 flower/min.) in EC399313 as compared to other bees in different varieties. Under caged pollination, line EC399313 was most preferred by A. mellifera with maximum abundance (6.24 bees/m2/2 min), foraging speed (2.33 s) and foraging rate (7.69 flower/min). The results indicated that A. mellifera visited all nine varieties/lines in both open and caged plots. Overall average abundance (4.09 bees/1 m2/2 min) and foraging speed (1.97s) of A. mellifera was found maximum under caged pollination while highest foraging rate (8.52 flower/min) was recorded in open pollination per day.   Key words: Brassica juncea, foraging behavior, Insect pollinators, caged pollination, open pollination.