Our lab is actively studying the effects parasites and pesticides on honey bee health, two factors that are thought to play a roles in honey bee declines and, potentially, in Colony Collapse Disorder. The microsporidian parasite, Nosema, poses a major problem for honey bee health and is associated with honey bee colonies that have collapsed. Currently, Daren Eiri is studying the effect of Nosema apis at different doses on the growth, development, and adult behaviors of honey bee larvae.
Nosema ceranae spores (green ovals) photographed on a hemocytometer under a light microscope at 400x. The inset photo shows a honey bee larvae in comb.
Our research on pesticides focuses on the effects of the pesticides Spinosad and imidacloprid. Recently, we began a collaboration with Mexican researchers in Chiapas at El Colegio de la Frontera Sur to explore the compatability between the use of Spinosad in agriculture and social pollination by Mexican bees. Spinosad consists of spinosyn A and spinosyn D and is derived from a soil bacterium.
Imidacloprid is found in several types of common garden pesticides (check the active ingredients list) and in seed dressings. We are interested in (1) how bees are exposed to imidacloprid, (2) how this compound affects their willingness to forage, and (3) how it affects their navigation.
Currently, we are completing studies on how imidacloprid affects the sucrose response threshold of honey bees and how bees are able to resist this pesticide. Natural nectar sources vary in their concentration of sugars. Each forager has a minimum threshold, the lowest concentration of sugar that she will feed upon. In the lab, harnessed foragers are given a sequence of increasing sucrose concentrations and the lowest sucrose concentration that will elicit feeding (proboscis extension) is the sucrose response threshold. Thus far, our experiments reveal that sublethal doses of imidacloprid can elevate this response threshold. As a result, bees become like “picky eaters,” only feeding on higher sucrose concentrations than control bees. If such bees forage less and reject more natural nectar sources, less food would flow into the nest. This should reduce colony health (Eiri and Nieh, 2010).
Interestingly, winter foragers are more resistant to the effects of imidacloprid than summer foragers. This may be related the presence of elevated levels of the egg precursor protein vitellogenin, which is significantly higher in winter than summer bees and which is associated with bee longevity, health, and immunity. Lee BenVau is currently investigating this phenomenon.
We will also continue to investigate the behavioral effects of pathogens and pesticides, using flight mills to determine how these stressors affect honey bee flight, essential for colony food collection and for mating of virgin queens.
Learn more about the study of Trophic Interactions and Animal Behavior at UCSD.
Information for San Diegans
Are you a beekeeper with questions about local bees? The San Diego Beekeeping Society has great information for you. This group meets regularly and welcomes new members.
Do you have a swarm or a colony that you would like humanely removed rather than exterminated? This site has a list of people who can help you out.
Would you like to learn more about honey bee disease and parasites? This Penn State site has a document, A field guide to honey bees and their maladies that has great information and detailed photos.
Useful Links
Global declines in multiple bee species have been much in the news. Bees are important pollinators of agricultural crops as a keystone pollinators in multiple ecosystems. Much attention has been given in the press to Colony Collapse Disorder, which has led to declines in the honey bee population. However, this is part of a larger overall decline in pollinators. The following links provide useful information and other resources if you are interested in learning more about these problems. Find out what you can do to help pollinators.
Questions about Colony Collapse Disorder? the Mid-Atlantic Apiculture Research and Extension Consortium website has some of the best information about Colony Collapse Disorder, including documents from the US Working Group on Colony Collapse Disorder.
How can you help protect and promote pollinators? The Pollinator Partnership has highly useful information and brochures on how you can promote healthy habitats for bees. Their "Useful Resources" links is a particulately good place to look for more information.
What about native bees? The Xerces Society has excellent information about native bees such as bumble bees. These native species are also declining.
Help support research on honey bee declines
Please visit our online donation website. Thank you for your support!
References
Please note: The copyright of these articles (with the exception of Open Access articles) is with their respective publishers. By downloading an article, you agree to limit the use of the pdf file to printing of single copies for personal research and study. You may not modify the files in any way, or to use them for commercial purposes.
Eiri D.M., J.C. Nieh, 2010. Picky eater syndrome: The pesticide imidacloprid alters honey bee (Apis mellifera) sucrose response threshold, and potentially, colony health. Entomological Society of America, San Diego.