Overwintering hive loss, while lower last year, has jumped from 15 percent  17 percent with the first appearance of Varroa mite to around 30 percent in recent years, said Jeff Pettis with USDA ARS in Beltsville, Md. The decline is likely a result of starvation and poor queen health brought on by stressors, including Varroa mites, lack of pollen and nectar supplies, pesticides and pathogens. Colony Collapse Disorder is caused by some mixture of these stressors, though the exact components are unclear. Pettis emphasized reducing the impact of Varroa mite through a mixture of breeding and treatment. He also called for more standardization in treatment techniques and definitions of hive health to better compare results of treatments and inspections.

Jay Evans, also with USDA ARS Beltsville, noted that the genome has now been sequenced for the honey bee and also for Varroa mite. This could lead to new genetic techniques for improving queen health and conferring pest resistance on domestic bees. Evans also discussed the impacts of various bacterial and microsporidial diseases.

Gloria DeGrandi-Hoffmann, USDA ARS Tucson, shared information on a hive development model that allows researchers to assess the impact of various stressors on the chances of hive survival. She also discussed the nutrient profiles of various pollens, and how pesticides impact in-hive food sources created from the pollen and nectar that bees bring to the hive. Almond pollen is of high nutritional value to honey bees.

Nancy Horn at Yale University is researching microorganisms in the honey bee gut, their role in honey bee nutritional status and susceptibility to diseases and pests, and how pesticides may affect the balance of those microflora.

Honey bee diseases

Diana Cox-Foster at Pennsylvania State University discussed changes in honey bee diseases. Since 2006, there has been a significant increase in the number of different viruses detected in hives, many of them associated with poor honey bee health. Cox-Foster is looking at the impact of diseases on bee behavior and colony health and interactions with pesticides. She hopes to develop tools to deactivate viruses, as well as resistant stock for various diseases.

Penn State’s Dennis van Engelsdorp provided an update on various honey bee pests. Varroa is by far the biggest problem; colonies with more than seven mites per 100 bees are unlikely to survive the winter.

Miticides lead to healthier colonies, although there is documented resistance to fluvalinate and coumaphos, which are used to treat Varroa mites. Van Engelsdorp encouraged the use of mite-resistant breeding stock.

Reed Johnson with Ohio State University discussed research on the impacts of pesticides on the health of individual bees and colonies. More than 119 different pesticides have been detected on bees and in bee colonies. Research has found that Varroa miticides become more toxic to honey bees when the bees have been exposed to a number of fungicides.

Much of the research cited at the workshop reflects research priorities the Almond Board of California (ABC) has identified and funded in recent years. Each year, the Almond Board funds between $100,000 and $125,000 for research related to honey bee health.

Currently funded research projects are focused on improving genetic diversity in honey bees to enhance resistance to pests and diseases, and to transfer that technology to bee breeders for integration into commercial breeding stock. Additional research in cooperation with Project Apis m. seeks to encourage almond growers to provide forage before and after bloom as a supplemental food source for honey bees in almond orchards; this can optimize the health and chances of survival of overwintering bees, and thereby improve pollination.