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Title: INHERITANCE OF RESISTANCE TO ACARAPIS WOODI IN FIRST GENERATION CROSSES OF HONEY BEES

Author
item Danka, Robert
item Villa, Joseph

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2000
Publication Date: 12/1/2000
Citation: DANKA, R.G., VILLA, J.D., INHERITANCE OF RESISTANCE TO ACARAPIS WOODI IN FIRST GENERATION CROSSES OF HONEY BEES, JOURNAL OF ECONOMIC ENTOMOLOGY, 2000, VOL. 93, pgs. 1602-1605, EDITION #6.

Interpretive Summary: Tracheal mites are parasites of honey bees that can weaken or kill colonies. Some genetic lines of bees fortunately are able to resist infestation by these mites, but few efforts have been made to breed bees for enhanced resistance. Part of the lack of breeding effort may be due to poor understanding and documentation of the pattern of inheritance of resistance to mites. Knowledge of the relative abilities of queens (females) versus drones (males) to pass resistance to offspring also is unclear and is needed for efficient breeding. We measured how well first generation offspring colonies of a resistant parent bee stock withstand tracheal mite infestation. When resistant bees were crossed with each of five stocks of commercially available U.S. bees, the offspring colonies resisted mites almost as well as the resistant parent stock. Good resistance similarly was obtained in offspring colonies when resistant bees were crossed with a stock known to be highly susceptible to mites, regardless of whether the resistant parent was represented by the queen or drone side of the mating. Finally we measured the heritability of the trait of resistance. Heritability was estimated at 1.15; this very high number supports the conclusion that resistance is easily inherited. The results confirm and expand upon a few anecdotal reports of inheritance of resistance from resistant colonies. Bee breeders should be encouraged by these results because reliable resistance can be acheived if first generation offspring of resistant colonies are distributed.

Technical Abstract: Infestations of tracheal mites (Acarapis woodi) were measured in F1 colonies of honey bees (Apis mellifera). The colonies were produced by mating a stock (Buckfast) known to resist mite infestation to a variety of commercially available stocks or to a stock known to be susceptible to mites. Young, uninfested bees from progeny and parent colonies were simultaneously exposed to mites in infested colonies, then retrieved and dissected to determine resulting mite infestations. Reduced infestations similar to but numerically greater than those of the resistant parent bees occurred in all crosses made with resistant bees regardless of the relative susceptibility of the other parental stock. Reciprocal crosses between resistant and susceptible queens and drones proved equally effective in improving resistance. Based on a sibling analysis, the heritability of resistance to mite infestation was estimated as 1.15; this high figure supports a conclusion that genes for resistance to tracheal mites are incompletely dominant. Therefore, allowing resistant stock queens to mate naturally with unselected drones, or unselected queens to mate with drones produced by pure or outcrossed resistant queens, can be used for improving resistance of production queens.