Prof. Eric Mussen, who joined the UC Davis Department of Entomology in 1976, will also touch on the newly announced threat to honey bees, the parasitic phorid fly(Apocephalus borealis). San Francisco State University researchers, in work published in the Public Library of Science (PLoS One) journal, found that the parasitic fly lays its eggs in the honey bees; it was previously known to parasitize bumble bees, but not honey bees
The infested bees reportedly fly around like zombies and cannot return to their hives.
“This information explains why some, infested, honey bee adults leave the colony at night and are not likely to come back,” Mussen said. “The percent infestation level is not high enough to cause a Colony Collapse Disorder (CCD) loss, by itself. However, anything that further stresses the bee population and increases bee losses can contribute to CCD.”
Mussen said the fly “may be contributing to the loss of adult bees from colonies, but that probably is happening, also, in colonies that are not collapsing. CCD seems to be an additive malady, so losses to fly parasitism can join the other stresses. It does not appear to be a dominant factor. ”
The San Francisco researchers detected the fly parasite in some commercial hives in California and South Dakota. Mussen said that without surveys, “we would not know for sure how widespread it is. However, it is likely that a bumble bee parasite would be distributed at least as widespread as its bumble bee hosts.”
Mussen said he does not consider the fly a significant threat. “Honey bees have an amazing ability to ‘make up for’ unanticipated losses--like exposures to bee-toxic agrichemicals in the fields--to the adult population by rearing more brood than would be expected at that time of the year to return to normal populations size. So, if the colony is shrinking, abnormally, the bees often can re-establish the normal size by rearing ‘extra’ brood. However, depending upon the inherent genetic abilities of a specific colony to tolerate fly parasitism, some colonies might be prone to developing parasite levels that are overwhelming, and actually succumb to the infestations.”
