FIELD-TEST OF RESISTANCE TO ACARAPIS-WOODI (ACARI, TARSONEMIDAE) AND OF COLONY PRODUCTION BY 4 STACKS OF HONEY-BEES (HYMENOPTERA, APIDAE)

Characteristics of four stocks of honey bees, Apis mellifera L., were evaluated in colonies managed commercially for honey production at thr ee U.S. locations-one northcentral location (Iowa) and two south-centr al locations (Mississippi, Texas). Stocks were compared for 1 yr begin ning in October 1991 to determine the levels of infestation by trachea l mites, Acarapis woodi (Rennie), and to ascertain survival rates, lev els of honey production, and sizes of adult and brood populations. Tes t stocks were ARS-Y-C-1 (A. mellifera carnica Pollman, imported from Y ugoslavia), Buckfast (imported from the United Kingdom), Survivor (dev eloped from colonies in a Louisiana apiary believed to have had severe tracheal mite mite infestation), and Unchallenged (developed from a f eral Louisiana population never exposed to tracheal mites). Stocks ini tially were represented by 15-20 colonies at each location. After an i nitial inoculation of mite-infested bees in the autumn, infestation pe rcentages increased more markedly in the susceptible (Survivor and Unc hallenged) stocks than in the resistant (ARS-Y-C-1 and Buckfast) stock s. Mean infestation percentages in the resistant stocks remained <15% and thus were below levels associated with economic damage. Mean infes tation percentages in susceptible stocks ranged from 13 to 95% at each site during the final 6 mo of the study. Numbers of mites per infeste d bee differed between stocks in 4 of 21 samples: mite numbers tended to be greatest in Survivor bees and least in Buckfast bees. Mortality increased more rapidly among susceptible colonies than among resistant colonies as infestation increased in 1992. Honey production was great est Lv Buckfast, intermediate by Survivor, and least by Unchallenged a nd ARS-Y-C-1 colonies. Differences in population sizes of adult bees a nd brood occurred. in approximately half of samples taken in spring:in d autumn; Survivor and Buckfast colonies were most populous. Stock cha racteristics showed no interaction of genotype with environment, i.e., location. Our results support the feasibility of art approach using g enetically regulated resistance to manage problems caused by tracheal mites.