Nicholas W. Calderone

Genotypic variability in age polyethism and task specialization in the honey bee, Apis mellifera (Hymenoptera: Apidae)

SummaryThe currently accepted model for division of labor in honey bees, Apis mellifera, explains variation in the frequency at which workers perform specific tasks as the result of differences in age and environment. Although well documented, the model is incomplete because it fails to take genotypic variability among workers into account. We show that workers from two genetically distinct strains of honey bees differed in the age at which they began foraging and in the relative frequency at which they foraged for pollen. Workers from the two strains also exhibited significant spatial heterogeneity within the nest, suggesting that they differed in the frequency at which they performed within-nest tasks as well. A heuristic model of division of labor that incorporates genotypic effects is presented.

Evolutionary Genetics of Division of Labor in Colonies of the Honey Bee (Apis mellifera)

We observed division of labor in worker honey bees from three genetically distinct sources (two selected strains and a wild-type source) in a common colony environment. We demonstrate a genotypic component to variability in those elements of individual behavior necessary for the evolution of the individual and colony-level behavioral phenotype-variability in task specialization and variability in the age-based system of division of labor. We present a model for individual behavior that integrates the effects of variability in individual genotypes with the current model of age and environmental determinism. Sources of variation involving interaction of genotype and environment are not individually specified, but an analysis of foraging behavior shows that such interactions can be significant. This conflicts with the traditional view of the colony environment as a source of behavioral resemblance among workers. The colony environment may, in some cases, actually amplify phenotypic differences among individuals beyond that expected on the basis of their additive genotypes. Interactions among workers or among subfamilies may significantly affect the expression of genotypic variability in worker behavior, resulting in facultative specialists that perform tasks with increased efficiency. Conversely, genotypic diversity within a colony may reduce colony fitness. Workers with different response thresholds may operate less efficiently as a group than workers with similar values if this variability results in conflict among nestmates over how an activity should be performed. Worker behavior is characterized by two elements: the proportion of time spent performing specific tasks (task specialization) and the temporal pattern of task performance (temporal division of labor). Analysis of the evidence presented here suggests that these components may be independent of one another. Further, we show that variation in the temporal pattern of performance of nest activities is independent of variation in the ontogeny of foraging behavior. Both of these findings reveal considerable flexibility in the evolution of energetically efficient task groups.

Effects of interactions among genotypically diverse nestmates on task specialization by foraging honey bees (Apis mellifera)

SummaryRecent studies have shown that differences in patterns of task specialization among nestmate honeybee workers (Apis mellifera) can be explained, in part, as a consequence of genotypic variability. Here, we present evidence supporting the hypothesis that an individuals pattern of task specialization is affected not only by her own genotype, but, indirectly, by the genotypes of her nestmates. Workers from two strains of honey bees, one selected for high pollen hoarding, the other for low pollen hoarding, were observed in colonies of their respective parent strains and in colonies of the other strain. Worker genotype and host-colony type affected foraging activity. Workers from the high strain fostered in low-strain colonies returned with pollen on 75.6% of total foraging trips, while workers from the high strain fostered in high-strain colonies returned with pollen on 53.5% of total trips. Workers from the low strain fostered in low-strain colonies returned with pollen on 34.8% of total foraging trips while workers from the low strain fostered in high-strain colonies returned with pollen on 2.6% of total trips. Similar results were obtained in a second experiment. We suggest that workers influence the behavior of their nestmates indirectly through their effects on the shared colony environment. The asymmetry seen in the response of workers from these strains to the two types of colony environments also suggests that these genotypes exhibit different norms of reaction.

Temporal polyethism and behavioural canalization in the honey bee,Apis mellifera

Abstract Two models of temporal polyethism in the honey bee were evaluated. The developmental-programme model asserts a causal relationship between age and task performance. The foraging-for-work model asserts that this relationship is an epiphenomenon associated with a self-organizing system. The effect of a workers pre-foraging environment on task selection as a forager was also examined. Four groups of workers, emerging at 6-day intervals, were introduced to a colony. Workers in group 1 were introduced when less than 12xa0h old. Workers in groups 2 and 3 were divided into deprived and non-deprived groups. Non-deprived groups were introduced to the colony when less than 12xa0h old. Deprived groups were confined to an incubator for 12 days and 6 days, respectively, then introduced to the colony along with group 4 (

Genetic structure and division of labor in honeybee societies

Recent studies have demonstrated a genotypic component to the division of labor among worker honeybees. However, these studies used artificially-selected strains of bees or colonies derived from queens that were instrumentally inseminated with the semen from very few males. We present evidence for genotypic variability among groups of workers performing tasks in colonies with naturally-mated queens. These results demonstrate that genetic structure is a level of social organization in honeybees.

An In Vitro Evaluation of Botanical Compounds for the Control of the Honeybee Pathogens Bacillus larvae and Ascosphaera apis, and the Secondary Invader B. alvei

ABSTRACT Bactericidal and fungicidal effects of eight plant extracts on the growth of two honeybee pathogens, Bacillus larvae (causative agent of American foulbrood) and Ascosphaera apis (causative agent of chalkbrood), and Bacillus alvei (a secondary invader in European foulbrood), were evaluated. Cinnamon oil completely inhibited the growth of B. larvae at 10 ppm for 72 h. Camphor and citronellal inhibited all growth at 100 ppm for 72 h. Bay oil, clove oil, origanum oil, and thymol inhibited all growth at 1,000 ppm for 72 h, and α-terpinene inhibited all growth at 10,000 ppm for 72 h. Cinnamon oil completely inhibited the growth of A. apis at 100 ppm for 168 h. Bay oil, citronellal, clove oil, origanum oil and thymol inhibited all growth at 1,000 ppm for 168 h. Camphor inhibited all growth at 10,000 ppm for 168 h, and α-terpinene inhibited all growth for 72 h at 10,000 ppm. Cinnamon oil and thymol completely inhibited the growth of B. alvei at 10 ppm for 72 h. Bay oil, camphor and origanum oil inhibited...

Evaluation of sampling methods for determining infestation rates of the tracheal mite (Acarapis woodi R.) in colonies of the honey bee (Apis mellifera): Spatial, temporal, and spatio-temporal effects

Current sampling methods for estimating infestation rates of tracheal mites in colonies of the honey bee,Apis mellifera, assume that infested bees are randomly distributed and that temporal fluctuations in infestation rates occur homogeneously throughout the colony. We examined these assumptions. Samples of bees were collected from up to five locations in each of eight colonies, and colonies were sampled several times throughout the year. Estimates of infestation rates varied, depending on the location in the colony from which a sample was obtained. Temporal fluctuations in infestation rates did not always occur homogeneously with respect to sampling location. These results demonstrate that assumptions of current sampling protocols for estimating tracheal-mite infestation rates are often violated. Consequently, estimates derived using these methods may not be accurate, and conclusions based on such estimates may not be valid.