Progress 11/01/08 to 12/31/09
Progress Report Objectives (from AD-416) To field test, and demonstrate to Florida honey beekeepers, the use of ozone as a fumigant for decontaminating stored comb and hive materials from pesticides, insect pests, and diseases. Approach (from AD-416) Spores of Ascosphaera apis (the cause of chalkbrood in honey bees) and Paenibacillus larvae (the cause of foulbrood) will be exposed to different rates of ozone (0.5, 1 and 1.5 mg/kg) for different time periods (24, 48, 36, and 72 hours), and under different temperature and humidity conditions. The primary purpose of these experiments is to determine whether sterilization conditions can reasonably be reached by beekeepers in on-farm fumigation chambers during different times of the year, and in different parts of the country. This will accomplish a reasonable determination of the exposure conditions necessary to decontaminate comb of insect pests, pesticide residues, and bee pathogens. We will select one set of conditions most likely to work for all these problems under typical Florida weather conditions during the winter. If warmer conditions are required, then space heaters can be added to the fumigation chambers. Then, in collaboration with the Florida Dept. of Agriculture and Consumer Services, Apiary Section, honey beekeepers (or groups of beekeepers) interested in participating in the project will be identified. The beekeepers will provide supers of used comb that have suspected or known contamination problems (e.g. wax moth or small hive beetle infestation, foulbrood scales, and pesticide exposures). ARS will evaluate and rate samples of these nesting materials for all these contamination problems. Then the comb will be placed in a fumigation chamber and treated, as per ARS pre-determined recommendations. After treatment, the same frames of comb will again be evaluated for wax moths, small hive beetles, foulbrood, and pesticides to determine if the treatments were effective. In addition, the treated materials will be returned to the beekeepers for their use. Beekeepers will be given instructions for monitoring the effect of treatments on their hives to include: acceptance of the material by the bees (as compared to untreated controls with similar contamination problems and as compared to uncontaminated, untreated comb), honey production, and survival of the colonies. Apiary inspectors will assist in determining the level of diseases and other health issues, where possible. Some colonies may be moved out of state for pollination and honey production, in which case, beekeeper evaluations will be relied on. Significant Activities that Support Special Target Populations This year, laboratory experiments in a small fumigation chamber (10 cubic ft) to determine the concentration of ozone needed to kill honey bee pests and pathogens. Tests were conducted using 1000 ppm for up to 3 days. Significant mortality was achieved for chalkbrood, but not for foulbrood. Wax moths infesting comb (all stages) were also found to be readily killed using 500 ppm of ozone. Plans are underway to test 2,500 ppm for better pathogen control. Field trials with a commercial honey beekeeper were conducted using hive materials from the beekeeper. Initially, the fumigation chamber (3,000 cubic ft) was filled with 280 empty hives with old comb. However, the beekeepers had difficulty obtaining 1,000 ppm, so they reduced the number of hive bodies to 180, stacking the boxed by slightly turning each to allow ventilation between the hives in a stack. A fan was also placed in the room to circulate the ozone (which is heavier than air). In the third run, only 120 hives were used. Under these conditions, the beekeepers were able to obtain approximately 1,500 ppm for five days, but they had some difficulty with the reliability of the equipment and a technician from the manufacturer had to be called out on several occasions. The pesticides coumophos and fluvalinate were significantly reduced by the ozone treatments, especially at high concentrations. It was difficult to reduce the pesticides to below 100 ppb. Elimination of pathogens from the comb was also evaluated. Chalkbrood in non-sporulating bee cadavers placed in the comb was completely eliminated, and the viability of the spores from cadavers was greatly decreased by the treatments. Methods to better quantify the actual spore mortality levels were developed as result, but experiments using these methods are still underway. Foulbrood scales were also placed in the comb, however, ozone had no measurable effect on the viability of this pathogen at the test concentrations used. Better equipment for further field trials has been purchased. The ADODR monitored the progress on this project through various methods including telephone conference calls, site visits, and meetings to discuss project plans and accomplishments, validate project expenditures, and provide technical advice.