FORAGING DYNAMICS OF PEPONAPIS-PRUINOSA (HYMENOPTERA, ANTHOPHORIDAE) ON PUMPKIN (CUCURBITA-PEPO) IN SOUTHERN ONTARIO

A large population of Peponapis pruinosa, a solitary, oligolectic, gro und-nesting bee and important pollinator of cucurbits in the United St ates and Mexico, was studied foraging on pumpkin (Cucurbita pepo) at a site in Cambridge, Ontario, from 23 July to 30 August 1990. We measur ed the diurnal and seasonal foraging trends for P. pruinosa and compar ed our findings with those for P. pruinosa elsewhere. The females are active on flowers in the mornings from dawn on. The males are active l ater in the mornings and spend afternoons and nights in closed flowers . The seasonal emergence of the bees closely parallels that of the pla nts' anthesis. Diurnal activity is related to the availability of poll en resources on the flowers of C. pepo. Almost all pollen is removed f rom the synandria within 2 h of the start of foraging by female bees. Ambient temperature threshold for foraging by both sexes is about 10 d egrees C.