Source: KENTUCKY STATE UNIVERSITY submitted to
CONTROL OF VARROA DESTRUCTOR AND NOSEMA APIS IN HONEY BEE COLONIES
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0193884
Grant No.
(N/A)
Project No.
KYX-10-02-36P
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Oct 1, 2002
Project End Date
Sep 30, 2007
Grant Year
(N/A)
Project Director
Webster, T. C.
Recipient Organization
KENTUCKY STATE UNIVERSITY
(N/A)
FRANKFORT,KY 40601
Performing Department
Agriculture & Environmental Science
Non Technical Summary
The honey bee parasite Varroa destructor, and the disease caused by Nosema apis, greatly reduce the productivity of bee hives. This study explores genetic and cultural methods for control of Varroa destructor and Nosema apis without the use of hazardous chemicals inside the bee hive. By understanding the means by which Nosema apis is transmitted within the hive, improved control methods may be recommended.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2113010111020%
2113010113080%
Goals / Objectives
1. Honey bee colonies collected from various locations within Kentucky will be evaluated by four criteria which appear to confer some resistance to Varroa destructor. 2. Comb built from small-cell foundation will be studied for its effect on V. destructor reproduction and honey bee colony growth. 3. The possible transovarial communication of Nosema apis in infected queen honey bees, and subsequent infection of offspring from such queens will be evaluated. 4. Honey as an anti-protozoal treatment for Nosema apis infection will be evaluated.
Project Methods
1. Honey bee colonies which have been surviving in Kentucky for at least three years without chemical treatments for the parasitic mite Varroa destructor will be established in standard hive equipment and moved to a test apiary site. These and colonies of commercially available bee stock will be compared for (a) the bees' ability to detect and destroy mite-infested brood cells, (b) the bees' ability to inhibit mite reproduction, (c)the duration of the postcapping period during which mites mature inside of brood cells, and (d) the proportion of mites that are mutilated, among those fallen to the bottom of the hive. Any test colonies which perform significantly better than the commercial stock colonies will become the basis for a breeding program. 2. Honey bee colonies will be established on sheets of beeswax foundation with embossed cell size slightly smaller than that typically used by American beekeepers. The bees will produce smaller brood cells on this foundation. These colonies will be compared to colonies established on standard size foundation to determine whether mite reproduction is inhibited by the smaller cell size. 3. The honey bee disease caused by the microbe Nosema apis will be studied to determine whether it is communicated from the queen bee to her offspring via her ovaries. Queen bees will be inoculated with the disease. Subsequently the brood produced by these bees will be examined for the presence of Nosema apis DNA. 4. The abilty of honey to control the disease of bees caused by Nosema apis will be studied. Caged bees will be fed honey from a variety of sources, and inoculated with Nosema apis. The rate of infection of the bees will be compared to the floral source of the honey.

Progress 10/01/02 to 09/30/07

Outputs
OUTPUTS: Research to develop the polymerase chain reaction test for the detection of the pathogen Nosema apis in honey bees was successful. The technique was applied to test the relative susceptibility of queens vs worker bees, and the possibility that the disease can be transmitted from the queen's digestive system to her ovaries and then the eggs she lays. Research to test the efficacy of screened bottom boards to reduce varroa mite populations in hive, and to slow the development of acaricide resistance in varroa populations was conducted. Research to study the effects of honey from various honey types on Nosema apis infection was conducted. Research to study the effects of genetically modified corn pollen on honey bee queen rearing activities was conducted. Research to study the utility of visible and ultraviolet spectroscopy for detection of queen bee insemination, nosema infection in worker bee ventriculi, and hypopharyngeal gland development was conducted. Results were disseminated through scientific presentations (Entomological Society Conferences, American Bee Research Conferences and others, from 2002 to 2007. Lay presentations were made to national, regional and state beekeeping associations, from 2002 to 2007. A booklet on beekeeping (89 pp., 1000 copies) was printed and distributed to Kentuckians at beekeeping workshops, county extension offices and as requested by telephone or e-mail. Observation hives were constructed and established two locations in the state for the education of children and the general public. Field Days and workshops were conducted at the KSU farm and at beekeeping events around the state. Students mentored were high school interns, one of whom worked every summer in the lab with us, an undergraduate who completed an independent study project on the effects of Bt corn pollen, and a graduate student who studied the effects of nutrition on honey bee queen rearing. PARTICIPANTS: Thomas C. Webster was the P.I. for the project, initiating and guiding it. Etta Thacker assisted all aspects of the project, as the Research Assistant. TARGET AUDIENCES: Audiences were primarily beekeepers and those who require honey bee pollination for their crops. All racial and ethnic groups were targeted, but with a particular interest in beekeepers and farmers operating on limited resources and income. Extension and outreach activities included numerous lay presentations in Kentucky and other states, and frequent communications with individuals by e-mail, mail and telephone. PROJECT MODIFICATIONS: Additions to the project were justified by the apparent significance and value of the approach. The use of visible and near-infrared spectroscopy to detect nosema disease and other aspects of honey bee internal morphology appears to have great promise because it is quick, does not affect the bee under examination and might be modified to a simpler and less expensive system appropriate to beekeeping. The examination of the effects of Bt corn pollen on honey bee queen rearing is a novel approach to questions about the effects of genetically modified crops on beneficial insects, and could be enormously important considering the acreage currently planted in the U.S. The project was extended one year because of injuries and health problems in the immediate family of the P.I. and the consequent time needed for additional family care.

Impacts
Use of screened bottom boards for bee hives, to control parasitic varroa mites: The number of beekeepers using screened bottom boards to control Varroa destructor parasites in their hives has increased greatly over the past decade. Queries at state and regional beekeeping conferences indicate that the majority of experienced beekeepers now use this type of equipment. This change in behavior is probably due to research at KSU and elsewhere on the efficacy of screened bottom boards, and presentations to beekeepers regarding this system. KSU research showed that this system can reduce varroa infestations by over half, compared to hives with standard bottom boards. Consequently, the expense of conventional chemical use for varroa control is reduced, and the possibility of residues in honey is reduced. Further research at KSU suggests that screened bottom boards slow the development of acaricide resistance in varroa. This has additional economic benefits because it allows the acaricides to be useful for longer times. The finding that Nosema disease is not transmitted through the ovaries of an infected queen to the eggs laid by the queen shows that new control strategies for the disease are not necessary. That is, beekeepers do not need to extend the antibiotic treatments for their hives to eliminate Nosema infection in the queen's ovaries and brood developing from eggs laid by the queen. The finding that genetically modified (Bt) corn pollen does not affect honey bee queen rearing activities shows that beekeepers do not need to spend time and money moving hives away from fields planted with Bt corn.

Publications

  • Webster, T. C., E. T. Thacker, K. Pomper, J. Lowe, G. Hunt. 2008 in press. Nosema apis infection in honey bee (Apis mellifera) queens. Journal of Apicultural Research.
  • Proceedings and abstracts included: Webster, T C., E.M. Thacker and F.E. Vorisek. 2002. Measurement of live Varroa jacobsoni mitefall in honey bee hives. Proceedings of the 2nd International Conference on Africanized Honey Bees and Bee Mites. E.H. Erickson, R.E. Page and A.A.Hanna, eds. A.I. Root Medina,OH, pp. 169-170.
  • Webster, T. C., F. E. Vorisek and E. M. Thacker. 2004. Screened bottom boards slow the development of acaricide resistance in varroa mites. Proceedings of the American Bee Research Conference. American Bee Journal 144:408.
  • Webster, T. C., K. Pomper, G. Hunt and E. Thacker. 2006. Nosema apis detection by polymerase chain reaction (PCR). In Proceedings of the American Bee Research Conference. American Bee Journal. 146:451.
  • Webster, T. C. 2007. New ideas for observation hives. 2007 Beekeeping Institute, Young Harris College, Young Harris, GA
  • Webster, T. C. 2007. Colony collapse disorder, one perspective. 2007 Beekeeping Institute, Young Harris College, Young Harris, GA
  • Webster, T. C. 2007. Screen bottom boards for varroa control. 2007 Beekeeping Institute, Young Harris College, Young Harris, GA
  • Webster, T. C. 2007. Nosema ceranae: a new (or old?) disease of honey bees. 2007 Beekeeping Institute, Young Harris College, Young Harris, GA
  • Webster, T. C., J. Sedlacek, M. Moriarty. in press. Pollen from genetically modified corn does not affect honey bee queen rearing behavior. Proceedings of the Kentucky Academy of Science. 2007. Louisville, KY.
  • Encyclopedia entries: Webster, T. C. 2004. Honey bee. Encyclopedia of Entomology, J. Campinera, ed.
  • Webster, T. C. 2004. Tracheal mite. Encyclopedia of Entomology, J. Campinera, ed.
  • Journal articles included: Webster, T.C., K.W. Pomper, G. Hunt,E .M. Thacker, S.C. Jones. 2004. Nosema apis infection in worker and queen Apis mellifera. Apidologie 35:49-54.


Progress 01/01/06 to 12/31/06

Outputs
Honey samples from floral sources in Kentucky were tested for their efficacy in inhibiting Nosema apis infection in caged worker honey bees. All samples inhibited the disease when fed with N. apis spores, compared to sucrose solution fed with spores. Diluted honey with spores was not efficacious. Hence efficacy is related to a factor, such as osmotic strength, which is largely eliminated on dilution. Honey fed to caged worker bees two days after they were inoculated with spores did not affect subsequent infection, compared to sucrose solution.

Impacts
Data from this study indicate that the common beekeeping practice of feeding sugar syrup to bee hives allows infection with Nosema disease. Also, it is possible that a factor in honey which inhibits this bee disease may be exploited so that beekeepers would have a new method for control. However, the efficacy in such a control method would be in preventing new infection in bees rather than in eliminating the disease from already infected bees.

Publications

  • Huang, L., C. Wang and T. Webster. 2006. Mineral concentrations and color characteristics of Kentucky honeys. Association of Research Directors 14th Biennial Research Symposium.


Progress 01/01/05 to 12/31/05

Outputs
Queen honey bees were infected with an important bee pathogen, Nosema apis, to determine the extent to which the procedure of shipping queens by mail affects the disease development. We also determined whether the queens would pass the disease to their offspring via their ovaries. These are practical considerations because queen bees are routinely mailed across the United States. Queen honey bees donated by a commercial beekeeper were inoculated with Nosema apis spores, and then returned to their small, wooden shipping cages. The queens were then either mailed from Kentucky State University to Purdue University and mailed back, or kept confined in a dark cabinet for up to 11 days. A temperature logger shipped with the queens recorded spikes as high as 31 degrees C. (88 degrees F). When the queens returned to KSU they were dissected, as were those not shipped, and their ovaries and ventriculi were removed for analysis. The Nosema apis DNA was extracted from these organs, amplified by the polymerase chain reaction, or PCR, technique, and isolated on agarose gel. All of the queens that survived the shipment (14 of 14) had ventriculi infected with Nosema apis, according to this technique. A lower proportion (42 of 49) of the queens that had remained confined but were not shipped had infected ventriculi, although this difference is not statistically significant. No queen ovary had detectable N. apis DNA in this study. Hence, we found the effect of mail shipping on the development of Nosema apis in queen bees to be statistically insignificant. However, further studies may show an effect. This study, in addition to earlier studies using the PCR technique, does not support the idea that queen bees can transmit the pathogen Nosema apis via their ovaries to their eggs. Consequently, we do not recommend changes in how beekeepers evaluate their hives and treat for this disease.

Impacts
This study informs commercial beekeepers of the effects of mailing queen honey bees on the development of an important bee pathogen, Nosema apis. Their customers depend on the receipt of disease-free bees. Since we found no clear evidence that shipping exacerbates infection with this pathogen, remedial treatment with antibiotics may not be economically beneficial. Our finding that no pathogen DNA could be detected in the queen ovaries leads us to recommend no changes in treatment protocol for this honey bee disease.

Publications

  • No publications reported this period


Progress 01/01/04 to 12/31/04

Outputs
We simulated the infection of queen bees with nosema disease to determine whether queens can pass the disease to their offspring via their ovaries. Queen honey bees were removed from their hives, inoculated with Nosema apis spores, and then returned to their hives. At later dates, eggs and larvae laid by those queens were sampled from the hives. Subsequently the queens were captured again, and their ovaries and ventriculi were removed. Samples were frozen until DNA was extracted from them. The PCR amplification procedure we developed for an earlier study was employed to determine whether Nosema apis DNA was present in any of the samples. Many of the queens clearly had N. apis infection in their ventriculi, but no ovary, egg or larva samples were positive for N. apis DNA. In a follow-up study, we simulated the procedure by which queen bees are routinely shipped to beekeepers in the U.S. This shipping seems to be stressful to the bees and may exacerbate disease. Queen honey bees were inoculated with N. apis spores and then either (1) mailed to Purdue University and mailed back, or (2) kept confined in small mailing cages for up to 11 days. The ovaries and ventriculi were then removed and frozen. DNA extraction and amplification is not completed at this time.

Impacts
To date, our study does not indicate that queen bees can transmit the pathogen Nosema apis to their eggs, and the larvae that develop from the eggs. Consequently, we do not recommend changes in how beekeepers evaluate their hives and treat for this disease. However, we expect to have more data on this issue in early 2005. Consequently, we make no firm conclusions at this time.

Publications

  • Webster, T. C., F. E. Vorisek and E. M. Thacker. 2004. Screened bottom boards slow the development of acaricide resistance in varroa mites. Proceedings of the American Bee Research Conference. American Bee Journal 144:408.
  • Webster, T. 2004. Honey bees. Encyclopedia of Entomology. Kluwer Academic Publishers.
  • Webster, T. 2004. Tracheal mites. Encyclopedia of Entomology. Kluwer Academic Publishers.


Progress 01/01/03 to 12/31/03

Outputs
Worker and queen honey bees were inoculated with the honey bee pathogen Nosema apis to compare the relative sensitivity of queens and workers. After three to seven days, the proportion of workers that became infected (0.60) was similar to the proportion of queens that became infected (0.75; p>0.10). The bees were examined for the disease by two methods. One was the standard procedure of looking for N. apis spores in the ventriculi of the bees by light microscopy. The second method was by extracting DNA from the bee ventriculi and amplifying it by polymerase chain reaction (PCR), using primer sequences specific to N. apis DNA. Light microscopy allowed the detection of infection in 28 of 52 worker ventriculi, while the PCR detected infection in 50 of the 52 ventriculi. Thus the PCR method was more sensitive (p<0.001).

Impacts
The finding that queen bees are as sensitive as worker bees to inoculation with the disease-causing microbe Nosema apis indicates that queens have no inherent resistance to the disease. N. apis is widespread in honey bee hives in the United States. Consequently, beekeepers and commercial queen producers must be persistent in their efforts to control the disease and to watch for signs of infected queens. This study also demonstrated a sensitive test for detection of N. apis in honey bees. The test will facilitate further studies of the disease, because it is more sensitive than the standard procedure of examining bee tissues for N. apis spores.

Publications

  • Webster, T. C., K. W. Pomper, G. Hunt, E. M. Thacker and S. C. Jones. in press 2004. Nosema apis infection in worker and queen Apis mellifera. Apidologie 35:49-54.
  • Webster, T. C. in press 2004 . Honey Bee. in Encyclopedia of Entomology. J. Capinera, ed. Kluwer Academic Publishers, Hingham MA.
  • Webster, T. C. in press 2004. Tracheal Mite. in Encyclopedia of Entomology. J. Capinera, ed. Kluwer Academic Publishers, Hingham MA.


Progress 10/01/02 to 12/31/02

Outputs
Honey bee colonies with small-cell foundation, and colonies which appear to carry traits for varroa mite (Varroa destructor) resistance were prepared for winter. Ultraviolet and visible light scans were conducted on honey from six floral sources, to determine the wavelengths at which they differ. The spectra of the six samples differed considerably.

Impacts
We hope to see whether small-cell foundation and bees with resistance to Varroa destructor reduce beekeepers' need for acaricides which are expensive and could possible leave chemical residues in hive products. If honey from certain floral sources inhibits infection by Nosema apis within the hive, we may be able to identify and use certain substances from honey to control the infection.

Publications

  • No publications reported this period