Progress 01/01/03 to 12/31/03
Outputs
This project's goals were to 1) test Integrate Pest Management (IPM) tactics for varroa control on honey bees, 2) develop varroa thresholds for the Mid-Atlantic region and 3) assist in the development of an essential oil for varroa control. The base level of mites in colonies varied tremendously among years. In 2001 and 2003, mite levels were low, while in 2002 the mite levels were moderate. In both 2001 and 2003 the tested IPM tactic did not significantly reduce mite number while in 2002 independent and statistically significant relationships between the presence of screen inserts (p=0.01) and hygienic queens (p=0.05) in colonies and lower mite levels were observed. One possible cause of the variation between years may be inconsistency in hygienic queen stock. Substantially greater variation existed in mite levels in colonies with hygienic queens than in colonies with non-selected queens. Colonies with the lowest mite levels were those with hygienic queens but
hygienic queen colonies with high mite level equal to those with non-selected queens were observed also. Screen inserts have the most impact when mite levels are above a minimum number. In the two years with low mite levels, no significant reduction in mite levels was observed in colonies with screen inserts. Weather data are undergoing analysis to determine if correlations exist between various environmental parameters and mite levels. Mite threshold levels are being field tested by beekeepers in the Mid-Atlantic region. An August/September threshold of 50 mites per day on a 3-day natural mite-drop sticky board has been established. Using overwintering data, a powdered sugar shake threshold for August/September of 10 mites has been calculated. Early and mid-summer thresholds need to be established as we have observed that colonies that exceed the threshold and are successfully treated to reduce mites have lower survivorship than colonies that never exceeded the August/September
threshold. Formulations of essential oils (primarily thymol) have been finalized, field tested and shown to be 94% effective. Microencapsulation at 10, 20 and 50% active ingredient per encapsulation has been successfully incorporated into bee diet. Early data show 54% fewer reproductive mites entering cells in treated colonies. This project has been successfully completed. More hygienic genetic selection is needed to decrease the variability in mite-reducing ability. Colonies with screens only, no bottom boards, need to be tested to determine if greater mite reductions are possible. Additional work is planned for the development of earlier thresholds. Preliminary data indicate that mite levels are related initially to virus levels but virus levels do not drop after mites have been killed indicating that lower mite thresholds might be necessary when viruses are present. The essential oil tested in this experiment continues to be developed and our assistance in testing the material in
the future will continue.
Impacts
Honey bees, an important pollinator of over 90 fruit and vegetable crops and other non-agricultural plants, are valued at $14.6 billion dollars per year. The existence of honey bees is threatened by an external parasite, varroa mites. In the mid-1990 nearly all feral honey bee colonies disappeared in the United States due to varroa mites. This research has demonstrated several ways to reduce mite numbers in honey bee colonies. Screen inserts successfully reduce mite numbers while queens genetically selected for their mite reducing ability are less successful at redcuing mites because of the large variations in mite reducing abilities among selected queens. We have successfully determined the number of mites that is damaging to a colony in the Mid-Atlantic region when using two different monitoring techniques. Beekeepers will be able to choose the most convenient monitoring method and reduce the quantity of coumaphos (and organophosphate pesticide) or fluvalinate (an
pyrethroid pesticide) used in honey bee colonies by only treating those colonies that exceed the mite threshold. We were able to show that a less toxic chemical, thymol, is effective in reducing mite numbers. The Integrated Pest Varroa management strategies tested in this study provide beekeepers with methods to reduce the quantity of pesticides used in honey bee colonies, thus reducing consumer pesticide exposure. Additionally, beekeepers will benefit by the decrease in adverse effects to honey bees from coumaphos exposure.
Publications
- Caron DM, Hubner J. 2003 (abstract). Monitoring Varroa Mite Populations. American Bee Journal 143(4):318.
- Caron DM, Hubner J. 2003. 2003 Winter Losses. American Bee Journal 143(2):145-146.
- Caron DM. 2003. Bees and People. BeeCulture 131(8):20-22.
- Caron DM. 2003. Bees for Develpment. BeeCulture 131(2):27-28.
- Caron DM. 2002. Woodpeckers as Bee Pests. American Bee Journal 142(6):421-422.
- Caron DM. 2002 Determining treatment threshold levels for Varroa mites in Honey Bee colonies. IN: E.H. Erickson, R.E. Page and A.A. Hanna, Eds. Proceedings of 2nd International Conference on Africanized Honey Bees and Bee mites. A.I. Root Co., Medina, OH. pp. 127-131.
- Caron DM. 2002. Pollination Ecology (Review of Bees & Crop Pollination: Crises, Crossroads and Conservation. Entomological Society of America Publication) American Bee Journal 142(3):159.
- Hubner J. 2003. Economic feasibility of IPM for Varroa mites. M.S. Thesis. University of Delaware, Newark, DE. 56 pp.
- Ostiguy N. 2003. Organic Honey in the United States. HiveLights 16(1):23.
- Ostiguy N, Frazier M, Sammataro D, Caron D. 2002. Why Should I Monitor for Varroa Mites and What is the Best Way to Do It? Bee Culture 130(4):37.
- Ostiguy N, Sammataro D. 2002. Environmental and Other Factors: Can They Be Used to Control Varroa? Proceedings of the Second International Conference on Africanized Honey Bees and Bee Mites, Editors: E.H. Erickson Jr., R.E. Page Jr., A.A. Hanna, A.I. Root Company, Medina Ohio.
- Park A, Caron DM. 2002. What's in a name? American Bee Journal 142(3):183-185.
- Park A, Pettis JS, Caron DM. 2002. Use of household products in the control of small hive beetle larvae and salvage of treated combs. American Bee Journal 142(6):439-442.
- Sammataro D, Degrandi-Hoffman G. Wardell G, Finley J, Ostiguy N. 2004. Testing a Combination of Control Tactics to Manage the Varroa destructor Mite (Acari: Varroidae) Levels in Honey Bee (Hymenoptera: Apidae) Colonies, in press International Journal of Acarology.
- Sammataro D, Ostiguy N, Finley J, Frazier M, DeGrandi Hoffman G, Wardell G. 2002. A New IPM Approach to Manage Varroa Mite (Acari: Varroidae) Levels in Honey Bee (Hymenoptera: Apidae) Colonies. Proceedings of the Second International Conference on Africanized Bees and Bee Mites, Editors: E.H. Erickson Jr., R.E. Page Jr., A.A. Hanna, A.I. Root Company, Medina Ohio.
- Sammataro D, Ostiguy N, Frazier M. 2002. How to Use a PSU/IPM Varroa Board, How to Use an IPM Sticky Board to Monitor Varroa Levels in Honey Bee Colonies, American Bee Journal 142(5):363-366.
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Progress 01/01/02 to 12/31/02
Outputs
Nearly all of our colonies overwintered successfully during the 2001-2002 winter and the summer 2002 season began with 3 apiaries and 20+ colonies per apiary. Data loggers were installed in 55 of the 70 colonies. One colony at each apiary was designated an "immigrant control" colony to determine if mites were migrating into the apiary. The following data were collected during summer 2002 on the influence of hygienic queens and screen inserts on varroa population size: natural mite drop, location, supercedure, and colony size and health, ambient temperature, humidity, light intensity and rainfall amount. Preliminary data analysis indicates that significant differences exist between treated and untreated colonies. We observed a significant decrease (p=0.054) in the number of mites in colonies with hygienic queens as compared to those colonies without hygienic queens. A significant decrease in mites was also observed in colonies with screen inserts (p=0.011). In addition
to main effects, interaction effects were observed. Significantly more mites were observed in colonies with neither screen inserts nor hygienic queens than in colonies with both screen inserts and hygienic queens (p=0.027). An interaction between screen inserts and location was also observed; no screen resulted in higher mite levels in some locations than others (p=0.021). Further work needs to be done using the weather data collected at each site to determine if the reason for locations differences can be explained. While hygienic queens and screen inserts significantly reduced the number of mites in colonies and the effect of these IPM tactics was even greater when combined, none of the treatments were sufficient eliminate the need for chemical treatment at the end of the season. Material sent from the Tucson Bee Lab for testing was used in colonies that exceeded the mite threshold and significant numbers of mites were killed. Colonies have been checked since entering winter and
overwintering success is not better in the treated colonies. At this time we suspect that the mite levels exceeded threshold earlier in the season and the colonies were "the walking dead" prior to treatment. For this reason we have begun to emphasis to beekeepers that monitor for mites early in the year is essential. The lack of monitoring early in the season may results in unnecessary use of a miticide, monetary waste, and chemical exposure for the beekeeper, bees and consumer. We are defining threshold levels and comparing monitoring methods. The threshold prediction of 50 mites per day natural fall monitored with sticky traps was validated with a second season of fieldwork. Comparison of whole colony sticky trap with adult bee sampling data collection has completed and analysis begun to enable development of sequential and/or dual sampling prediction. Data analysis of mite levels throughout the season and colony survivorship, irrespective of chemical treatment, is underway.
Impacts
The existence of honey bees are threatened by varroa. Our work will reduce mite levels and pesticide use by beekeepers. We are testing tactics to reduce mite population growth rates, methods to monitor mite level and threshold efficacy, and ways to kill mites by using the least toxic alternatives. Prior to 1988 few pesticides were used in beekeeping. With the introduction of Varroa destructor into the United States, fluvalinate began to be used. In 1998, mite resistance to fluvalinate became widespread and special approval for the use of coumaphos was obtained. Both fluvalinate and coumaphos are persistent, lipid soluble compounds that accumulate in beeswax. Coumaphos, an organophosphate pesticide, is moderately toxic to bees and moderately toxic to people. Coumphos has been shown to be toxic to queens raised in queen rearing operations and may be one of the factors leading to poor queen performance. Fluvaliniate and coumpahos have been detected in hive products and,
due to the chemical characteristics of these substances, is more likely to accumulate in beeswax than in honey. Concern has been expressed that with high levels of wax contamination, honey may become contaminated. The Integrated Pest Management strategies being tested in this study, if successful, will reduce the quantity of pesticides used in honey bee colonies, thereby reducing consumer pesticide exposure. Additionally, beekeepers will benefit by the decrease in adverse effects to honey bees from coumaphos exposure.
Publications
- Ostiguy, N., Kahkonen, B., and Frazier, M. 2002. IPM Tactics to Manage Varroa destructor in Honey Bee Colonies (Abstract). American Bee Journal. Accepted for publication.
- Ostiguy, N., Frazier, M., Sammataro, D., Caron, D. 2001. An Update on Determining Varroa Mite Levels on Adult Honey Bees (Abstract). American Bee Journal, 141(12): 892.
- Sammataro, D., Ostiguy, N., Frazier, M. 2001. Results of a Novel IPM Experiment to Management Varroa Populations in Honey Bee Colonies (Abstract), American Bee Journal, 141(12):893-894.
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Progress 01/01/01 to 12/31/01
Outputs
Initial analysis of the summer 2000 data indicated that IPM tactics had no significant effect on varroa levels or colony health. This result was expected because we had been unable to install mite-reducing queens in colonies due to no funds. We expected that a lack of mite reducing queens, one of the control tactics that we found very effective in summer 1999 (p=0.001), would adversely impact our ability to reduce mite levels. An error was discovered recently with these data that may change the results after re-analysis. In spring 2001 weather stations were placed at two apiaries. The third apiary, located at the University farm already had a weather station. Additional data loggers were installed in colonies, bringing the total number of data loggers in colonies to 55. Processing of the weather data from the data loggers and weather stations has begun. These data will allow us to determine when colony death occurred during overwintering and the relationship between
temperature variables and mite levels. The following data were collected during summer 2001 on the influence of IPM tactics (mite-reducing queens, screen inserts) on varroa population size: natural mite drop, temperature, humidity, light intensity, and other weather data, location, queen acceptance, supercedure, and colony size and health. Preliminary analysis indicates that mite levels were low in all colonies. A complete data analysis will be done as soon as all mite counts are complete. We suspect that environmental conditions in summer 2001 were not conducive for high mite population levels; therefore, we designed several other experiments that could be completed without interfering with the long-term IPM study. The first experiment tests the relationship between fall mite threshold and overwintering success. The natural mite drop and colony survival are being measured; these data will be evaluated in mid spring 2002. The remainder of colonies were treated with Apistan and mite
drop was continuously monitored for 42 days to create a data set that would allow for the estimation of total colony mite number, when the mite load is low, from a 3-day natural mite drop. We have a data set of very high mite drops and these new data will be used to determine if the slope differs when the total number of mites in the colony is low. A second experiment was designed to determine alternative methods for evaluating hygienic behavior. The currently accepted method uses liquid nitrogen, which beekeepers are reluctant to use. These data are being evaluated. A third experiment was designed to evaluate the effectiveness of wrapping hives for overwintering. While beekeepers are currently advised to wrap hives not located in a protected area, no data exist on the effectiveness of hive wrapping. These data will be available for evaluation in late spring 2002. Threshold and overwintering data from Delaware are being collected as part of these experiments and will be combined with
the Pennsylvania data for analysis. The Tucson Bee Lab provided botanical material for testing in hives reserved for this work. Data analysis is underway.
Impacts
The work being done will reduce the quantity of pesticides used by beekeepers in their honey bee colonies. Prior to 1988 few pesticides were used in beekeeping. With the introduction of Varroa sp. into the United States, fluvalinate began to be used. Since 1998 a special approval for the use of coumaphos has been approved because Varroa sp. resistance to fluvalinate. Both fluvalinate and coumaphos are persistent, lipid soluble compounds that accumulate in beeswax. The Integrated Pest Management strategies being tested in this study, if successful, will reduce the quantity of pesticides used in honey bee colonies, thereby reducing consumer pesticide exposure. Additionally, beekeepers will benefit by the decrease in adverse effects to honey bees from coumaphos exposure.
Publications
- No publications reported this period
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Progress 01/01/00 to 12/31/00
Outputs
We established 50 honey bee colonies at 2 sites located in State College, Pennsylvania. One site is located in a clearing of a secondary growth forest while the second site is near the top of a hill in a field. The first site (sheltered) is surrounded by trees and has little air movement. The second site (open) has no trees on three sides and approximately 500 on the east side of the apiary there is a windbreak of mature trees. The colonies were monitored throughout the summer for varroa mite levels using sticky boards. The sticky boards are placed at the bottom of hive to capture mites that fall off the honey bees. The boards are placed in the hive for 3 days to obtain a one day average natural mite fall. These boards were brought back to the lab for counting and we will soon have the final mite numbers. In October colony health was assessed and the colonies were prepared for over-wintering. As soon as the final mite numbers have been determined and the data entry
for mite numbers and colony health information have been completed, data analysis will begin. Because summer 2000 had such odd weather we are uncertain if there will be any useful information to be obtained from this season. As part of the study, we installed data loggers in all the colonies to record temperature and humidity throughout the winter. To determine the effect the honey bees have on temperature and humidity, we installed data loggers in empty hives. Weather stations are being installed in each of the apiaries. This will allow us to correlate data from the data loggers in the hives and ambient conditions. With this information it will be possible to provide recommendations to beekeepers about hive placement. We have begun to prepare for the start of the new season. We will need approximately 25 hives more than we currently have. Hives boxes are being constructed from the material already purchased and additional hives will be purchased before March. Arrangements have been
made to obtain packages of bees and queens for installation in hives. The bees will arrive in May and the queens (the strains of bees we wish to study) will arrive by June. (It is necessary to establish the colony for approximately one month before installing new queens.) More data loggers have been ordered for the additional 25 hives we will be placing into the study. All hives will have data loggers and each apiary will have a weather station. Treatment hives will have screened bottom boards and mite-reducing queen stock. As mite number increase above a natural mite fall of 100 per day, colonies will be treated with the thymol oil being tested.
Impacts
The work being done will reduce the quantity of pesticides used by beekeepers in their honey bee colonies. Prior to 1988 few pesticides were used in beekeeping. With the introduction of Varroa sp. into the United States, fluvalinate began to be used. In 1998 the EPA issued a Section 18 for the use of coumaphos because Varroa sp. resistance to fluvalinate had been found. Both fluvalinate and coumaphos are persistent, lipid soluble compounds that accumulate in beeswax. The Integrated Pest Management strategies being tested in this study, if successful, will reduce the quantity of pesticides used in honey bee colonies, thereby reducing consumer pesticide exposure. Additionally, beekeepers will benefit by the decrease in adverse effects to honey bees from coumaphos.
Publications
- No publications reported this period
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