Christina M. Grozinger, Jessica Richards, Heather R. Matilla
Department of Entomology, Center for Pollinator Research, The Pennsylvania State University, 4A Chemical Ecology Lab, Orchard Road, University Park, PA 16802, USA
Department of Biological Sciences, Wellesley College, 106 Central Street, Wellesley, MA 02481, USA Received 16 July 2013 – Revised 18 October 2013 – Accepted 25 October 2013
Abstract – Reproduction by colony fission, or swarming, is a spectacular example of a behavior that requires the simultaneous coordination of the activities of thousands of honey bee workers and their queen. The successful execution of this collective phenomenon relies on the appropriate response of individuals in swarms to a myriad of signals that are produced by workers and queens to synchronize their nest exodus, subsequent house hunting, and eventual relocation to a new nest site. In this review, we describe our current understanding of the social factors that trigger swarming in colonies and the nonchemical and chemical signals that mediate a coordinated transition between its stages. We also highlight emerging work on the physiological and genomic mechanisms underpinning swarming behavior. Finally, we discuss the possible evolutionary origins of swarming behavior, through comparisons with related behaviors of migration, overwintering, estivation, and diapause in honey bees and other insects.
PESTS & PREDATORS
WASHINGTON STATE UNIVERSITY EXTENSION FACT SHEET • FS017E
Samuel D. Ramsey, Ronald Ochoa, Gary Bauchan, Connor Gulbronson, Joseph D. Mowery, Allen Cohen, David Lim, Judith Joklik, Joseph M. Cicero, James D. Ellis, David Hawthorne, and Dennis vanEngelsdorp
Proceedings of the National Academy of Sciences of the United States of America (PNAS) January 29, 2019 116 (5) 1792-1801; first published January 29, 2019
Edited by Gene E. Robinson, University of Illinois at Urbana–Champaign, Urbana, IL, and approved December 6, 2018 (received for review October 26, 2018)
Abstract: The parasitic mite Varroa destructor is the greatest single driver of the global honey bee health decline. Better understanding of the association of this parasite and its host is critical to developing sustainable management practices. Our work shows that this parasite is not consuming hemolymph, as has been the accepted view, but damages host bees by consuming fat body, a tissue roughly analogous to the mammalian liver. Both hemolymph and fat body in honey bees were marked with fluorescent biostains. The fluorescence profile in the guts of mites allowed to feed on these bees was very different from that of the hemolymph of the host bee but consistently matched the fluorescence profile unique to the fat body. Via transmission electron microscopy, we observed externally digested fat body tissue in the wounds of parasitized bees. Mites in their reproductive phase were then fed a diet composed of one or both tissues. Mites fed hemolymph showed fitness metrics no different from the starved control. Mites fed fat body survived longer and produced more eggs than those fed hemolymph, suggesting that fat body is integral to their diet when feeding on brood as well. Collectively, these findings strongly suggest that Varroa are exploiting the fat body as their primary source of sustenance: a tissue integral to proper immune function, pesticide detoxification, overwinter survival, and several other essential processes in healthy bees. These findings underscore a need to revisit our understanding of this parasite and its impacts, both direct and indirect, on honey bee health.
Population growth of Varroa destructor (Acari: Varroidae) in honey bee colonies is affected by the number of foragers with mites
Gloria DeGrandi-Hoffman, Fabiana Ahumada, Victor Zazueta, Mona Chambers, Geoffrey Hidalgo, Emily Watkins deJong
Carl Hayden Bee Research Center, USDA-ARS Tucson USA, AgScience Consulting LLC Tucson USA
Abstract: Varroa mites are a serious pest of honey bees and the leading cause of colony losses. Varroa have relatively low reproductive rates, so populations should not increase rapidly, but often they do. Other factors might contribute to the growth of varroa populations including mite migration into colonies on foragers from other hives. We measured the proportion of foragers carrying mites on their bodies while entering and leaving hives, and determined its relationship to the growth of varroa populations in those hives at two apiary sites. We also compared the estimates of mite population growth with predictions from a varroa population dynamics model that generates estimates of mite population growth based on mite reproduction. Samples of capped brood and adult bees indicated that the proportion of brood cells infested with mites and adult bees with phoretic mites was low through the summer but increased sharply in the fall especially at site 1. The frequency of capturing foragers with mites on their bodies while entering or leaving hives also increased in the fall. The growth of varroa populations at both sites was not significantly related to our colony estimates of successful mite reproduction, but instead to the total number of foragers with mites (entering and leaving the colony). There were more foragers with mites at site 1 than site 2, and mite populations at site 1 were larger especially in the fall. The model accurately estimated phoretic mite populations and infested brood cells until November when predictions were much lower than those measured in colonies. The rapid growth of mite populations particularly in the fall being a product of mite migration rather than mite reproduction only is discussed.