Gerald M. Loper

Environmental physiology of the invasion of the Americas by Africanized honeybees.

The expansion of Africanized honeybees (AHB) through the Americas has been one of the most spectacular and best-studied invasions by a biotype. African and European honeybees (EHB) hybridize, but with time, tropical and subtropical American environments have become dominated by AHB that exhibit only 20-35% genetic contribution from western European bees, and a predominance of African behavioral and physiological traits. EHB persist in temperate environments. Clines between AHB and EHB exist in ecotones of South and Central America, and are forming in North America. What individual-level genetic, behavioral and physiological traits determine the relative success of the AHB as an invader in the neotropics, and of the EHB in temperate areas? Preference for pollen versus nectar may be an important trait mediating these ecological trade-offs, as preference for pollen enhances nutrient intake and brood production for the AHB in the tropics, while a relative preference for nectar enhances honey stores and winter survival for EHB. AHB exhibit morphological (higher thorax-to-body mass ratios) and physiological (higher thorax-specific metabolic rates) traits that may improve flight capacity, dispersal, mating success and foraging intake. Enhanced winter longevity, linked with higher hemolymph vitellogenin levels, may be a key factor improving winter survival of EHB. Data from South America and distributions of AHB in the southwestern United States suggest that AHB-EHB hybrids will extend 200 km north of regions with a January maximal temperatures of 15-16°C. The formation of biotypic clines between AHB and EHB represents a unique opportunity to examine mechanisms responsible for the range limit of invaders.

Mating frequencies of Africanized honey bees in the south western USA

Summary Emerging evidence suggests that there are significant adaptive advantages conferred to genetically diverse honey bee colonies through multiple matings with queens. We determined the intracolony genetic diversity of Africanized honey bee (AHB) colonies from a feral population in the south western USA. A total of 1,253 worker offspring were genotyped from 20 feral colonies (all but three of African mitotype), four managed AHB, three managed European honey bee (EHB), and four control colonies (headed by EHB queens instrumentally inseminated with one, two, five, or ten drones, respectively) using eight microsatellite markers. The 17 feral AHB queens mated with an average of 20.0 ± 6.53 (range 10–32) drones, resulting in effective paternity frequencies of 20.0 ± 8.46 (range 10.56–37.53), which is one of the highest mating numbers recorded within the species. Though Africanized honey bee colonies are among the most genetically diverse Apis mellifera yet recorded, their queen mating frequencies are within the expected range of the species overall, including African honey bees in their native range. The factors responsible for these findings are discussed.

Use of drone trapping and drone releases to influence matings of European queens in an Africanized honey bee area (Hymenoptera: Apidae).

SUMMARYA series of releases of virgin European honey bee (Apis mellifera) queens was made in a 4-km2 area dominated by African honey bees (AHB) near Ciudad Hidalgo, Chiapas, Mexico, in November-December, 1989. Queens were allowed to mate before and after experimental manipulations of the local drone population. After the first series of queen matings, aerial drone traps were used to capture and eliminate 6 398 drones. Then, approximately 6 400 drones of known colour (yellow) from managed European colonies were introduced into the area via drone source colonies, and a second series of queen matings was done. The drones caught in aerial traps were colour sorted. Essentially, 80% of the drones during the first mating period were black (MDH allelic frequencies typical of feral Africanized bees). During the second mating period, the percentage of black drones was much lower, averaging 53%. The drone population manipulations resulted in a significant increase (from 47.4% before to 93.6% after) in the proportion...

BEEAMATE: A honeybee colony genetics models

Abstract BEEAMATE is a computer model that simulates the genetic composition of a honeybee (Apis mellifera L.) colony, and determines the number of individuals carrying particular combinations of alleles at any time (t). Determination of a colonys genetic composition is made as a function of the genotype of the queen and the drones with which she mates. BEEAMATE is constructed to be a module to a larger honey bee colony population model (BEEPOP). Population size is predicted by the BEEPOP model, and is divided into subpopulations with different genotypes by BEEAMATE. Simulations were conducted to determine the number of brood cycles needed to change the genetic composition of a colony depending upon the time of year during which the queen is introduced, weather conditions, and the size and genetic composition of the initial colony population. How BEEAMATE simulations might be used to conceptualize the Africanization of European hives is also discussed.