There are a good many beekeepers and scientists scratching their heads about tracheal mites. Nobody seems to be able to reconcile why high mite levels last fall did not necessarily translate into large colony losses this spring. Informal reports from California to Michigan reveal this quandary. One prominent researcher summed it up:1
“I still have not figured out the tracheal mite…A year ago one of the colonies that survived the winter was headed by a daughter queen from the Lonesome Hive (a single colony kept in the yard). It had a tracheal mite level of about 80% at that time. It still has the same queen this year, and yet the tracheal mite levels have dropped from 33 to 45% in the two samples that we have examined this winter. At the inspection yesterday (April 18, 1991), I had to divide the colony since it had five hive bodies (3/4 depth supers) full of bees. They were starting queen cells!”
1 R. Hoopingarner, B-Plus, Michigan State Cooperative Extension Service newsletter, Summer, 1991.
Other pieces of evidence add to the confusion. It seems that researchers in the Rio Grande Valley of Texas, where the first detection of Acarapis woodi occurred in 1984, are unable to keep mite levels high enough to do effective research on the critter. Early studies in Florida were also plagued with very large variation in mite populations that confounded investigators. Some California beekeepers had high mite levels in their colonies last fall and were expecting the worst, but in contrast to previous years’ experience, most hives came through the winter with flying colors. Beekeepers in Florida’s panhandle have not experienced losses similar to those in 1986 and 1988 which many attributed to tracheal mites. Some colonies in Florida have traditionally had high mite infestations, but never suffered the devastation visited on those in the panhandle.
The tracheal mite situation parallels many disease and pest situations in beekeeping which appear to ebb and flow through the years. For example, I have heard reports of an extreme chalkbrood epidemic in Israel and the Brazilian-Argentinean border continues to be affected with an outbreak of antibiotic-resistant American foulbrood. It seems that beekeepers are not immune from similar often seasonal situations that plague other agriculturalists. Prevailing environmental conditions will favor certain disease or pest problems each year in ways that are often not predictable.
