Preliminary observations on thermoregulation, clustering, and energy utilization in African and European honey bees.

Abstract

Honey bees of the African race Apis mellifera scutellata evolved under and subtropical conditions, while the different races of European bees evolved under temperate conditions (Ruttner, 1975, 1976). Although Africanized bees have been thought of as hybrids between these two groups of bees, they are more similar to their African ancestors in morphology (Daly and Balling, 1978) and behavior (Fletcher, 1978; Winston et al., 1979; Otis, 1980; Winston et al., 1983). African (Africanized) and European bees have notable differences in morphology, behavior, and physiology of adaptive value to tropical and temp?rate en vironments, respectively (Winston et al., 1983). This concept is clearly substan tiated by the failure of European bees over centuries to form noticeable feral populations in the American tropics, contrasting with the dramatic success of African bees in colonizing a vast portion of the continent (Taylor, 1977). On the other hand, European bees form feral populations in temperate regions of America, and African bees have failed to colonize at high densities such areas in Argentina (Taylor, 1977; Kerr et al., 1982). Some of the comparisons that have been made between European and African bees consider the characteristics of each race in habitats similar to the ones in which each race evolved. Although side-by-side comparisons would be most meaningful, several biologically important trends are discernible from studies of each race in different regions. Individual African bees are smaller (Otis, 1982), develop faster (Kerr et al., 1972; Fletcher, 1978), forage at an earlier age (Winston and Katz, 1982), and have shorter lifespans (Winston and Katz, 1981). These African characteristics promote faster colony growth and rapid arrival at a swarm ing-age structure (Winston et al., 1980), leading to frequent reproduction by swarming (Otis, 1980), and on the average smaller sizes of colonies with less stores accumulated (Winston et al., 1983). Absconding is the most viable strategy for African colonies encountering periods of regional lack of resources or other un favorable local conditions, while maximum storage is advantageous for European colonies faced with more predictable and widespread unfavorable winter condi tions (Winston et al., 1983). Another adaptation of African bees toward unpre dictable daily conditions is a tendency towards individual foraging which makes them more successful on scattered low-reward food sources (Rin dereretal., 1984). The differences encountered so far between African and European honey bees