Current Research Interests

Link to research: http://msa.ars.usda.gov/la/btn/hbb/jwh/SMRD/SMRD.htm

Program goals: Breed and select honey bees with resistance to varroa mites.

Major activities: Varroa mites (Varroa destructor) remain the most destructive parasites of honey bees (Apis mellifera) worldwide. My major focus is the selective breeding for bees that are varroa-resistant, and determination of the mechanisms of resistance in these bees. In co-operation with John Harbo (retired USDA-ARS), I produced lines of bees that resistance to the growth of varroa populations. Selection was based on the presence of low percentages of reproductive mites capable of producing a mature daughter. The bees were said to have the SMR trait because they carried a genetic characteristic that “suppresses mite reproduction”.

The primary mechanism of resistance in SMR bees is the removal of varroa-infested pupae from capped brood cells. In particular, honey bees expressing the trait target pupae infested with varroa mites that produce offspring, which gives the impression that mite reproduction is being inhibited. The name for SMR bees was recently changed to VSH bees, which more accurately identifies the mechanism of resistance as Varroa-sensitive hygiene (VSH). VSH is similar to other forms of hygienic behavior that bees direct at brood that is killed by freezing or puncture, brood infected by bacteria or fungi, brood invaded by larvae of the small hive beetle (Aethina tumida), or brood invaded by larvae of the greater wax moth (Galleria mellonella).

I am currently investigating details of Varroa-sensitive hygiene. Hygienic responses to dead, diseased, or parasitised brood are the culmination of actions by several bees. The process begins with an initial detection of an abnormal condition, followed by uncapping of the cell and the eventual removal of the affected host larva or pupa. However, removal of the host from uncapped cells is not always the final outcome. Often uncapped cells are re-sealed without the host pupa being injured. In the case of Varroa, sometimes the foundress mite escapes or is removed by the bees while the cell is uncapped. My current focus is to try and identify the chemical stimuli that elicit removal of Varroa-infested pupae from brood cells by the attending worker bees.

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People

Personnel: David F. Dodge; Biological Technician whose duties include all basic beekeeping work involved with major projects, maintenance of support colonies, and laboratory and field measurements of variables related to growth of populations of honey bees and varroa mites.

Cooperators: none external to the laboratory.

Courses

Non-research activities: I have taught two graduate courses within the Department of Entomology (Biology and Management of Honey Bees - ENTM 4011; Fundamentals of Insect Physiology - ENTM 4016).

Funding is through approved ARS CRIS projects.

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