Hindrance in Rearing of Bumble Bee, Bombus hoemorrhoidalis (Smith)

Studies on rearing of bumble bee conducted during 2008–2010 revealed problems in successful establishment of colony under laboratory conditions. Twenty five queens were captured while foraging in the field during each year. These were maintained at 26 + 1^oC temperature and about 65% RH for rearing in wooden cages (size: 150x 80x65mm). Out of the caged bumble bee queens, 9.3% queens formed wax mounds, honey cups, laid eggs and initiated rearing worker bees, 45.5% formed wax mounds, honey cups but laid no eggs and 45.2% survived up to 4 months without any activity. Studies revealed presence of larva or pupa of some parasite in the abdomen of about 20% queens which were identified as conopid fly. These flies considered to lay eggs on adult bees while foraging in the field. The larva after hatching enters into the abdomen of queen and starts feeding on their abdominal contents. It pupates and overwinters inside the infested queens. That's why, the development of conopid fly inside the queen affected the egg laying and caused death. Further observations on dissected queens (90.7%) revealed presence of spermathecae without any sperms in about 65.3% queens which indicates that in nature some unmated queens overwinters. These studies revealed that hindrance in successful rearing or initiation of colony development / egg laying may be due to parasitization of queen bumble bees by this fly or survival of unmated queens in nature.