Progress 10/01/02 to 09/30/07
Outputs OUTPUTS: The outputs of this project fall into three categories: 1) a formal, detailed report in a scientific journal (Apidologie), 2) three informal reports in a trade journal for beekeepers (Bee Culture), and 3) 17 talks at meetings of beekeepers throughout the U.S. (New York, Ohio, Maryland, New Jersey, Pennsylvania, Massachusetts, Maine, Vermont, Connecticut, Oklahoma, Missouri, Minnesota, and Wisconsin.
PARTICIPANTS: Dr. Thomas D. Seeley, Professor, Dept. of Neurobiology and Behavior, Cornell University Dr. Koos Biesmeijer, Professor, Dept. of Animal and Plant Sciences, Leeds University Dr. Heather Mattila, Postdoc, Dept. of Neurobiology and Behavior, Cornell University
TARGET AUDIENCES: There are two target audiences of this project: 1) professional biologists of honey bees (apiculturists), who are trying to understand how honey bees and Varroa mites can evolve a stable co-existence, and 2) beekeepers, who are struggling to keep their bee colonies alive despite being infested with Varroa mites. For the former group, this work has highlighted the fact that in feral colonies, there is selection for avirulence among the mites as well as selection for resistance among the bees. For the latter group, this work clarifies how the traditional methods of beekeeping (crowding colonies in apiaries, transfering bees among colonies, and inhibiting swarming) promote the evolution of virulence among the mites.
Impacts Feral colonies of European honey bees living in the Arnot Forest, a 1651-ha research preserve in New York State, were studied over a five-year period, 2002 to 2007. This population of colonies was previously censused in 1978. A census in 2002 revealed as many colonies as before, even though Varroa destructor was introduced to North America in the intervening years. Most colonies located in fall 2002 were still alive in fall 2005. The Arnot Forest colonies proved to be infested with V. destructor, but their mite populations did not surge to high levels in late summer. To see if Arnot Forest bees can suppress the reproduction rate of mites, colonies of Arnot Forest bees and New World Carniolan bees were inoculated with mites from an apiary and the growth patterns of their mite populations were compared. No difference was found between the two colony types. Evidently, the stable bee-mite relationship in the Arnot Forest reflects adaptations for parasite (mite) avirulence,
not host (bee) resistance. This work provides the first solid evidence that feral colonies of honey bees still exist in the eastern U.S., and it shows how these feral colonies can survive despite being infested by the introduced parasite, Varroa destructor. This work has highlighted the fact that in feral colonies, there is selection for avirulence among the mites as well as selection for resistance among the bees. This work has also clarified how the traditional methods of beekeeping (crowding colonies in apiaries, transfering bees among colonies, and inhibiting swarming) promote the evolution of virulence among the mites.
Publications
- Seeley, T.D. 2003. Bees in the forest, still. Bee Culture 131 (January):24-27.
- Seeley, T.D. 2004. Forest bees and Varroa mites. Bee Culture 132 (July):22-23
- Seeley, T.D. 2007. Honey bees of the Arnot Forest: a population of feral colonies persisting with Varroa destructor in the northeastern United States. Apidologie 38:19-29.
- Seeley, T.D. 2008. Honey bees of the Arnot Forest. Bee Culture. In press.
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Progress 01/01/06 to 12/31/06
Outputs During the summer of 2006, I continued to monitor the feral honey bee colonies living in the Arnot Forest of Cornell University to gather additional data on their longevity despite being infested by the parasitic mite, Varroa destructor. This monitoring involves a check of each of the colonies living in trees three times each summer: May, July, and September. It also involves a monthly (1 May to 1 October) inspection of each of the colonies living in movable-frame hives that I have mounted in trees and that have been occupied by feral swarms. This summer, I also continued an experiment to test whether the persistence of these feral colonies even though they are infested with Varroa is because the bees have evolved resistance to the mites (host resistance hypothesis) or because the mites living in these feral colonies have evolved avirulence (parasite avirulence hypothesis). The results of my experiment support the parasite avirulence hypothesis. I have published a
report on this work in the premier journal reporting apicultural work, Apidologie. Here is the abstract of this manuscript: 'Feral colonies of European honey bees living in the Arnot Forest, a 1651-ha research preserve in New York State, were studied over a three-year period, 2002 to 2005. This population of colonies was previously censused in 1978. A census in 2002 revealed as many colonies as before, even though Varroa destructor was introduced to North America in the intervening years. Most colonies located in fall 2002 were still alive in fall 2005. The Arnot Forest colonies proved to be infested with Varroa, but their mite populations did not surge to high levels in late summer. To see if Arnot Forest bees can suppress the reproduction rate of mites, colonies of Arnot Forest bees and New World Carniolan bees were inoculated with mites from an apiary and the growth patterns of their mite populations were compared. No difference was found between the two colony types. Evidently,
the stable bee-mite relationship in the Arnot Forest reflects adaptations for parasite (mite) avirulence, not host (bee) resistance.'
Impacts It is widely believed, probably correctly, that the introduction of the mite Varroa destructor in the mid 1980s has all but wiped out the feral populations of honey bees in North America. Nevertheless, work on this project has shown that a feral population of these bees, infested with Varroa, persists in the Arnot Forest in New York State. An experiment conducted in 2005 indicates that the basis for this stable host-parasite relationship is the evolution of avirulence (reduced reproduction) in the Varroa mites, not resistance (mechanisms of mite control) in the honey bees.
Publications
- Seeley, T.D. 2007. Honey bees of the Arnot Forest: a population of feral colonies persisting with Varroa destructor in the northeastern United States. Apidologie 38: 1-11.
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Progress 01/01/05 to 12/31/05
Outputs During the summer of 2005, I continued to monitor the feral honey bee colonies living in the Arnot Forest of Cornell University to gather additional data on their longevity despite being infested by the parasitic mite, Varroa destructor. This monitoring involves a check of each of the colonies living in trees three times each summer: May, July, and September. It also involves a monthly (1 May to 1 October) inspection of each of the colonies living in movable-frame hives that I have mounted in trees and that have been occupied by feral swarms. This summer, I also performed an experiment to test whether the persistence of these feral colonies even though they are infested with Varroa is because the bees have evolved resistance to the mites (host resistance hypothesis) or because the mites living in these feral colonies have evolved avirulence (parasite avirulence hypothesis). The results of my experiment support the parasite avirulence hypothesis. The fall of 2005
brings my study of the feral bees in the Arnot Forest to the three-year mark, a point where I have enough information to make a formal scientific report. Accordingly, I have written a manuscript which has been submitted to the premier journal reporting apicultural work, Apidologie. Here is the abstract of this manuscript: 'Feral colonies of European honey bees living in the Arnot Forest, a 1651-ha research preserve in New York State, were studied over a three-year period, 2002 to 2005. This population of colonies was previously censused in 1978. A census in 2002 revealed as many colonies as before, even though Varroa destructor was introduced to North America in the intervening years. Most colonies located in fall 2002 were still alive in fall 2005. The Arnot Forest colonies proved to be infested with Varroa, but their mite populations did not surge to high levels in late summer. To see if Arnot Forest bees can suppress the reproduction rate of mites, colonies of Arnot Forest bees and
New World Carniolan bees were inoculated with mites from an apiary and the growth patterns of their mite populations were compared. No difference was found between the two colony types. Evidently, the stable bee-mite relationship in the Arnot Forest reflects adaptations for parasite (mite) avirulence, not host (bee) resistance.'
Impacts It is widely believed, probably correctly, that the introduction of the mite Varroa destructor in the mid 1980s has all but wiped out the feral populations of honey bees in North America. Nevertheless, my work on this project has shown that a feral population of these bees, infested with Varroa, persists in the Arnot Forest in New York State. An experiment conducted in 2005 indicates that the basis for this stable host-parasite relationship is the evolution of avirulence (reduced reproduction) in the Varroa mites, not resistance (mechanisms of mite control) in the honey bees. The results have substantive implications for future NY production of bee products (honey) and also for agriculture products dependent on fertilization by bees. In addition, the study reinforces new understandings of the social dynamics of insect colonies.
Publications
- No publications reported this period
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Progress 01/01/04 to 12/31/04
Outputs During the summer of 2004, I continued to monitor the feral honey bee colonies living in the Arnot Forest. This involved a May, July, and September inspections of the colonies living in trees, to determine their continued survival. It also involved monthly (1 May to 1 October) inspections of the colonies living in movable-frame hives that I have mounted in trees and that have been occupied by feral colonies. The monthly inspections of the colonies in hives include a measurement of the level of the Varroa mites in the colonies, by counting the number of mites that fall onto a sticky board on the floor of each hive over a 48-hour period. This work has revealed that the colonies (both those in the trees and in the hives) continue to thrive, despite infestation by mites, These findings confirm what I observed over the summer of 2003, raising my confidence that these bees are indeed able to survive without treatment for the mites. Now that this fact is well documented, I
need to determine the mechanism of colony survival despite the mites. There are two main possibilities: (1) the bees have evolved resistance to the mites, and (2) the mites have evolved avirulence to the bees. Next summer I will test the hypothesis that the bees have evolved resistance to the mites. I have removed one colony of bees from the Arnot Forest, and next summer I will use this colony as a source of genetic stock. I will set up paired colonies, one of Arnot Forest stock and one of standard stock, inoculate each with mites from my lab colonies, and over the summer I will compare the mite populations in the two types of colonies. If the Arnot Forest bees have resistance to the mites, then colonies of these bees should maintain lower mite populations than the colonies of the standard bees.
Impacts This project is determining whether or not feral colonies of honey bees are able to survive in New York State without treatments against parasitic mites. Because two years of data indicate that feral colonies are coping with the mites, the project is also determining whether the bees have evolved resistance to the mites, or the mites have evolved avirulence in the bees, or both.
Publications
- Seeley, T.D. 2004. Forest bees and Varroa mites. Bee Culture 132 (July):22-23.
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Progress 01/01/03 to 12/31/03
Outputs During 2003, I started the next stage of my work on the restoration of wild colonies of honey bees to New York State. It had been generally believed that the introduction of the parasitic mite, Varroa destructor, from Asia, has virtually eliminated the wild colonies in New York State, but this view was revised in 2002 when I conducted a census of the wild colonies of honey bees in the Arnot Teaching and Research Forest. To my surprise, I found as many, if not more, wild colonies living in the Arnot Forest as I found there the last time I made a census, back in 1978. This discovery raised the question of how these wild colonies are managing to survive. There are 3 possibilities: (1) this population of colonies is so isolated that it has not become infested with Varroa; (2) these bees have evolved resistance to Varroa; and (3) the mites have evolved avirulence in this population of colonies. The evolutionary theory of diseases supports the last possibility, for in this
population of wild colonies, unlike in the population of beekeepers colonies, the hosts of the parasite are widely dispersed and the mode of transmission of the mites among colonies is probably mostly vertical (from parent to offspring) rather than horizontal (between unrelated individuals), hence selection is predicted to favor parasitic strains that do not kill their hosts. To test the first possibility (hypothesis), I placed empty hives in the Arnot Forest, with the hope that some would be occupied by wild swarms. If so, then I would be able to inspect these colonies to see whether they are infected by Varroa and if they are, whether they are able to persist despite infection. Three of the hives were occupied by swarms. All three colonies are infected with Varroa, which disproves the first hypothesis. And all three colonies thrived throughout the summer of 2003, which is consistent with both hypothesis 2 and hypothesis 3. I will repeat this test in the summer of 2004, to increase
the sample size and to see whether the infected colonies can live with the mites for longer than one year. After this, the next step in the study will be to conduct studies that will test hypothesis 2 (evolution of host resistance) and hypothesis 3 (evolution of parasite avirulence). Both hypotheses could be true.
Impacts Wild colonies of honey bees have lived in the forest regions of the eastern United States ever since they began to be introduced from Europe in the 1620s. Until the mid 1990s, they surely outnumbered the managed colonies of beekeepers in this part of the world, and so provided a great deal of pollination for free. Sadly, the number of wild colonies in the eastern forests has fallen in recent years, due to the introduction of the parasitic mite of honey bees, Varroa destructor. The existence of a thriving population of wild colonies in Cornells Arnot Forest may reflect natural selection for resistance to this parasite. If this proves to be the case, then the wild colonies in the Arnot Forest are likely to be an important resource in the breeding of a hardy, Varroa-resistant honey bee for beekeepers.
Publications
- Seeley, T.D. 2003. Bees in the forest, still. Bee Culture 131:24-27.
- Seeley, T.D. 2003. Consensus building during nest-site selection in honey bee swarms: the expiration of dissent. Behavioral Ecology and Sociobiology. 53:417-424.
- Seeley, T.D. and A.S. Mikheyev. 2003. Reproductive decisions by honey bee colonies: tuning investment in male production in relation to success in energy acquisition. Insectes Sociaux 50:134-138.
- Seeley, T.D., Kleinhenz, M., Bujok, B., Tautz, J. 2003. Thorough warm-up before take-off in honey bee swarms. Naturwissenschaften 90:256-260.
- Seeley, T.D. 2003. Beauty and the bees. [Review of Form and Function in the Honey Bee, by Lesley Goodman, International Bee Research Association, 2003.] Nature 424:372-373.
- Seeley, T.D. and P.K. Visscher. 2003. Choosing a home: how the scouts in a honey bee swarm perceive the completion of their group decision making. Behavioral Ecology and Sociobiology 54:511-520.
- Seeley, T.D. 2003. What studies of communication have revealed about the minds of worker honey bees. In: Genes, Behavior, and Evolution in Social Insects, ed. T. Kikuchi. Pages 22-33. University of Hokkaido Press, Sapporo.
- Huang, M.H. and T.D. Seeley. 2003. Multiple unloadings by nectar foragers in honey bees: a matter of information improvement or crop fullness? Insectes Sociaux 50:330-339.
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Progress 01/01/02 to 12/31/02
Outputs This is a newly funded project that began October 1, 2002. No reportable progress at this time.
Impacts Invasive mites have impacted the population of honey bees, thus the pollination of plants that dependent on insect pollination or are more fruitful when numerous pollinating insects are present. By reintroducing the bees in the Arnot Forest with mite-resistance New York fruit and vegetable growers will see benefits through stronger, healthier and more fruitful crops.
Publications
- No publications reported this period
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