ABATING FERAL AFRICANIZED HONEY-BEES (APIS-MELLIFERA L) TO ENHANCE MATING CONTROL OF EUROPEAN QUEENS

Abatement of local feral honey-bee colonies was tested as a method to increase the mating control of European queens produced in an Africani zed area. Feral colonies within 2 km of a commercial mating apiary at Belen, Guanacaste Province, Costa Rica were targeted. Thirty-eight fer al colonies were discovered in the 12.5-km2 study plot between 13 May and 6 June 1992. Abatement techniques included dispensing avermectin-i vermectin paste (applied manually to the abdominal tergites of drones captured during mating flights) and acephate-treated sucrose syrup bai t (retrieved by foragers), and spraying nests directly with pyrethroid s. Twenty-one of the known colonies were killed or severely weakened b y treatments made between 27 May and 5 June. Mating control in pre-aba tement (n = 27) and post-abatement (n = 26) queens was estimated by me asuring changes in morphology and in frequencies of allozymes (malate dehydrogenase-1(100) and hexokinase-1(100)) of worker progeny relative to reference populations of workers from local Africanized (n = 35) a nd imported European (n = 23) colonies. Five of 23 morphological featu res shifted significantly toward the European form after abatement. Si gnificantly more post-abatement colonies (85%) than pre-abatement colo nies (63%) were classified by multivariate discriminant analysis as Eu ropean (ie with a probability of Africanization of < 50%). Paternal fr equencies of both allozymes were shifted significantly toward European frequencies following abatement; malate dehydrogenase decreased 26% a nd hexokinase increased 43%. Overall the results suggest that abatemen t may be useful in augmenting other mating control methods (eg, drone flooding and controlling mating times) but that it is probably not fea sible as a unilateral approach to achieving acceptable mating control in heavily Africanized areas.