Social insect colonies are organized by a reproductive division of labor, in which non-reproductive workers cooperate to rear the offspring of the queen. Queen pheromones, chemical compounds produced by queens that regulate worker fertility, have been identified in a handful of bees, ants, wasps, and termites. However, recent studies on bumblebee (Bombus spp.) queen signals have yielded conflicting findings. Here we provide an independent investigation of experiments to test the hypothesis that queen-produced non-volatile cuticular compounds influence worker’s reproductive behavior. We exposed small groups of Bombus impatiens workers to extracted cuticular compounds from queens collected from either mid-season (pre-reproductive) or late-season (reproductive) colonies and tracked worker reproduction and ovary development. We observed no difference in worker’s ovarian development or egg production when comparing among the mid-season queen extract, late-season queen extract and the solvent control treatments. Our data replicate the finding that body size positively correlates with ovarian development in workers. These results are consistent with recent studies showing that queen cuticular compounds do not inhibit worker reproduction in B. impatiens.
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We thank Biobest for providing bumblebee colonies, and Hollis Woodard for providing the frozen late-season queens used in Experiment I. Etya Amsalem, Jenny Jandt and Jocelyn Millar provided helpful advice. Funding for this project came from fellowships to V. M. from UCR Research in Science and Engineering (RISE) summer program and California Alliance for Minority Participation (CAMP-UCR). K. J. L. was supported by a USDA-NIFA postdoctoral fellowship.
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