Submitted to: Proceedings of the National Academy of Sciences
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/4/2007
Publication Date: 5/15/2007
Citation: Torto, B., Boucias, D.G., Arbogast, R.T., Tumlinson, J.H., Teal, P.E. 2007. Multitrophic interaction facilitates parasite-host relationship between an invasive beetle and the honey bee. Proceedings of the National Academy of Sciences. 104(20):8374-8378. Interpretive Summary: The beekeeping industry in the US is critical to many agricultural crops grown in the US. In fact pollination by domesticated European honeybees is the only way in which some crops, like almonds, are pollinated. Recently, an invasive pest of honeybees, the Small Hive Beetle was introduced into North America. Beetles invade hives and feed on pollen, bee brood, and ruin honey with their feces. As such, the beetle invasion has had a dramatic effect on the $14 billion/year apiculture and pollination industries in the United States, already are at risk from Varroa mites, other bee pests and diseases. Scientists at the Center for Medical Agricultural and Veterinary Entomology, USDA, ARS, in Gainesville Florida in collaboration with scientists at the University of Florida and Pennsylvania State University have discovered that the beetles are attracted to honeybee alarm pheromones. They also isolated a yeast vectored by the beetles which, when grown on bee collected pollen produces the bee alarm pheromones. European bees are less responsive to alarm pheromones and less aggressive in repelling intruders than the original host of the beetle, African honeybees, and, fail to recognize the beetle invasion until it is too late to avoid colony collapse. The scientists are currently using this knowledge to develop effective control programs for the beetle using in hive traps baited with these alarm pheromones.
Technical Abstract: Colony defense by honeybees is associated with a sting and mass attack, fueled by the release of alarm pheromones. As such, alarm pheromones are critically important to survival of honeybee colonies. However, we have discovered that in the host-parasite interaction involving the honeybee and the small hive beetle, Aethina tumida, the honeybee’s alarm pheromones serve as an attractant to the beetle. Further, the beetle is a vector of a yeast species that grows on pollen in hives and produces these same honeybee alarm pheromones, optimizing recognition of bee hosts and of conspecifics. Thus, the honey-beetle-yeast tritrophic interaction provides a fitness advantage to the beetle in host environments that favor growth of the fungus, which in turn, facilitates attraction of more beetles to the hive for reproduction and results in abandonment of the hive by the bees. We conclude that this tritrophic interaction has contributed significantly to the success of the beetle since its introduction into European honeybee (EHB) colonies in the United States and other places because EHBs are less responsive to alarm pheromones and less aggressive in repelling intruders than the original host of the beetle, African honeybees.