Improving honey Bee Health and Pollination Sustainability with Mite-Resistant Bees

Improving honey Bee Health and Pollination Sustainability with Mite-Resistant Bees

Summary

In 2009, we continued with selection and breeding of bees for resistance to Varroa mites. We developed a novel, more efficient lab assay to select for bees with higher mite-removal behavior. The assay was shown to be effective by a significant correlation between the proportion of mites removed in the lab and the proportion of mites that are chewed by the bees in the colony. Those colonies that removed more mites in the lab also had fewer mites on the adult bees in their colonies. Results were presented at the national American Bee Research Conference held in conjunction with the American Beekeepers Federation meeting. Results were also submitted for publication in Apidologie and to the two beekeeping trade journals. In addition, we obtained preliminary results on cage assays to screen for resistance to dysentery disease of bees. We set up two additional apiaries in addition to the 100 at Purdue. These apiaries will be re-queened in the spring of 2010 for testing commercial stocks against bees in the selection program for mite resistance.

Objectives/Performance Targets

An assay was developed that involves taking bees from the brood nest and keeping them in cages on a comb containing nectar and pollen without brood. Cages have screens on bottom and top so that mites that fall off the bees will fall onto an oiled white plastic sheet. After 3 days at room temperature, mites are counted on the sheet and also removed from the adult bees. The proportion of mites that fall are calculated. The proportion of mites that fell correlated with the proportion of mites that were chewed on similar sheets that were put at the bottom of the hives from which the bees originated (p<0.01). This proved that the lab assay is a legitimate measure of the mite-grooming behavior of the bees. In addition, the proportion of mites removed correlated inversely with the infestation of the adult bees, indicating that grooming behavior was reducing mite infestation. When presented at the national meeting, several large California queen producers expressed interest and at least one intends to incorporate this assay in their selection program. Results were also presented at beekeeper meetings in Indiana and one out-of-state regional meeting. In addition, preliminary cage studies involving inoculations with Nosema ceranae suggested there is variation in resistance to this dysentery pathogen.

In 2008, we increased from 50 to 100 hives involved in our selection program. In 2009,we set up two new apiaries of 30 hives each to compare the performance of queens from the selection program with queens from commercial suppliers commonly used in Indiana. Comparisons of mite levels, honey production and bee health will be made in 2010 and 2011. We raised queens from selected sources and these were open-mated in the mating yard, which was stocked with drone-producing colonies from selected lines.

In June of 2009, we conducted a 3-day queen-rearing shortcourse to enable hobby and sideliner beekeepers to rear their own queens. This should promote better genetic diversity and more “micro-breeders” to serve the needs of beekeeping within the state. We held a joint meeting of the two state beekeeping associations at the Purdue Bee Lab and also presented our results at the spring and fall meetings. One trip was made to the Central New Jersey Beekeepers meeting. In addition, results were presented by the graduate student supported by this project at the national meetings in Orlando Florida (see above).

Accomplishments/Milestones

• Increased colony base to 160 and added two new bee yards to test stock against commercial sources.

  Developed and validated a new mite-removal assay for selection of breeding lines.

  Conducted preliminary screens for resistance to dysentery caused by Nosema ceranae.

  Presented results at statewide, regional and national meetings.

  Published results for publications in research journal and trade journals.

  Conducted queen-rearing course for beekeepers.

Impacts and Contributions/Outcomes

• The maximum proportion of mites chewed by hives in our apiaries in 2006 was 8%. In 2009, we observed some colonies that chewed more than 40% of the mites that were falling off of the bees, showing that we are making progress in improving mite resistance in bees.

  30 people attended the queen-rearing shortcourse and now have the knowledge needed to raise their own queens.

  At least one California queen breeder intends to try the mite-removal assay to select for grooming behavior. Several California breeders specifically requested additional information on the use of the assay.

Collaborators: