In recent years, the nation's beekeeping industry has sustained serious losses of bee colonies from two introduced parasitic mites: Acarapis woodi (R) and Varroa jacobsoni. Both mites now infest bees in every state except Hawaii. As bee researchers and beekeepers became more familiar with these mites, symptoms of a new malady became apparent.

Dr. Shimanuki and his associates at the Beltsville USDA Research Laboratory named this disease the bee parasitic mite syndrome (BPMS). They chose this term based on evidence that the entire colony, both adult bees and food are affected. In addition, they suspect that mites may serve as vectors for viral and other communicable pathogens. The consequences of parasitism by two species of mites is especially troublesome because A. woodi parasitizes the adult bee, and V. jacobsoni targets the pupae.

For many years, we have observed a similar pathology in colonies of bees exposed to toxic pollutants. How colonies would respond to the cumulative effects of mites and pollution stress became a critical issue to our continued use of bees as monitors of environmental stressors. Therefore, in 1993, under a cooperative agreement with EPA's Office of Exploratory Research, we began a three-year project aimed at examining these issues. Our goal was to incorporate this information into a mite module (TMITE) for our ecotoxicological model.

We have just completed these studies and are in the process of submitting papers to peer-reviewed journals. These papers will fully describe the study and the results. A brief synopsis of the research is presented here. Several other investigators collaborated in this study, especially Dr. DeGrandi-Hoffman, Tucson, USDA Laboratory, and Dr. Sammataro, The University of Ohio. Dr. Sammataro provided the mite illustrations that accompany this page.

Tracheal Mite Studies Near a Lead Smelter

24-Month Field Trials

• Three Sites Downwind from Complex
• 48 Colonies
• 16 Colonies/Site
• Four Levels of Mite Infestation/Site
• Monthly Sampling of Bees for Mites
• 23,000+ Bees Examined for Mites
• Counts of Bees Infested & Mites per Bee
• Periodic Measurements of Colony Performance

Results

Significant Site x Treatment Effects:

• Number of Infested Bees per Sample
• Mean Number of Mites per Infected Bee

Interaction Plots Indicate:

Lower numbers of infected bees and mites were found in colonies with moderately low (initial) infestation levels of mites, especially on the low stress sites, compared to other sites and infestation treatments. The highest numbers of infested bees and the highest infestation rates were seen at the higher stress sites (nearest the smelting complex). Differences in response to increasing mite infestation and site stress produced the interaction effect.

Severe colony losses occurred in early fall of the second year at the site nearest the industrial facility. Colonies at the intermediate site perished mid winter. Colonies at the most distant site survived until the following spring. Eventually all but two colonies perished.