Years ago when both tracheal and varroa mites were beginning to show up in US bees, I did a 48 month, large scale study for EPA placing relatively large numbers of colonies at several apiaries near a lead smelter and sulfuric acid plant. These were non-migratory, commercial colonies placed in groups at apiaries in different compass directions and distances from the industrial complex. Each month, we sampled each colony for both mites. After 48 months we found - bee colonies exposed to the highest levels of heavy metals from the industrial complex succombed faster to mites. Both species of mites increased in population density at the fastest rates at the sites closest too and down wind from the smelter. By end of 48 months, the mites wiped out the colonies nearest the smelter (at the sites with the highest exposures to metals). At the start of the trial, we anticipated that the metals (lead, arsenic, copper) might possibly have a differential effect on the bees and on the mites. We even considered it possible that mites might be more susceptible to the metals than the bees, in which case, mite populations would have slowed in growth or diminished. No such luck, mites over ran bee colonies. In the end, mites gained in numbers, bees lost colonies, and of course, the lost colonies thenalso took their mites to the grave (so to speak) with them. We did not see any evidence that the metals affected the mites more than the bees. Mite populations increased for both species, bee colonies died quicker, closer to the smelter. My point, it was a classic scenario - metals exacerbated the mite problem. In a sense, we might have concluded that heavy metals increased fecundity - but I suspect it was more of a shift in the rates of reproduction and mortality of the host and the parasitoids. Bee reproduction tends to be reduced and overall mortality rate with shortened life spans were a common consequence of heavy metal exposure (we did this kind of work for nearly 20 years). Metal problems and bee losses were particularly bad in dry years and windy conditions, where the surfacial contamination of soils, re-entrained dusts containing high metal levels tended to result in higher exposures to the brood via metals in pollen. Bee populations slowed growth, bee colony age structures were altered. Mites on the other hands tended to thrive. *********************************************** The BEE-L mailing list is powered by L-Soft's renowned LISTSERV(R) list management software. For more information, go to: http://www.lsoft.com/LISTSERV-powered.html