Cooperation among unrelated ant queens provides persistent growth and survival benefits during colony ontogeny

The fitness consequences of cooperation can vary across an organism’s lifespan. For non-kin groups, especially, social advantages must balance intrinsic costs of cooperating with non-relatives. In this study, we asked how challenging life history stages can promote stable, long-term alliances among unrelated ant queens. We reared single- and multi-queen colonies of the primary polygynous harvester ant, Pogonomyrmex californicus, from founding through the first ten months of colony growth, when groups face high mortality risks. We found that colonies founded by multiple, unrelated queens experienced significant survival and growth advantages that outlasted the colony founding period. Multi-queen colonies experienced lower mortality than single-queen colonies, and queens in groups experienced lower mortality than solitary queens. Further, multi-queen colonies produced workers at a faster rate than did single-queen colonies, even while experiencing lower per-queen worker production costs. Additionally, we characterized ontogenetic changes in the organization of labor, and observed increasing and decreasing task performance diversity by workers and queens, respectively, as colonies grew. This dynamic task allocation likely reflects a response to the changing role of queens as they are increasingly able to delegate risky and costly tasks to an expanding workforce. Faster worker production in multi-queen colonies may beneficially accelerate this behavioral transition from a vulnerable parent–offspring group to a stable, growing colony. These combined benefits of cooperation may facilitate the retention of multiple unrelated queens in mature colonies despite direct fitness costs, providing insight into the evolutionary drivers of stable associations between unrelated individuals.

Vacant rooms? The secondary use of stem-galls by ants in Eremanthus erythropappus (Asteraceae)

Galls are atypical proliferations of plant tissue induced by highly specialized herbivores, such as some insect groups. Although gall inducers create these structures for their own purpose (food, habitat, protection against natural enemies, and harsh weather), many other organisms can use galls as secondary inhabitants. The creation of new and better habitats with ameliorated micro-environmental conditions allows for the use of many other organisms, and as such, some galling insects are considered "micro" ecosystem engineers. This study characterized the occurrence of ants in microhabitats created by a gall-inducing cecidomyiidae associated with Eremanthus erythropappus (DC.) Mac. Leish (Asteraceae). It was 153 individuals of ants belonging to three species in 19 galls (9.5%) from the 200 galls sampled. The most common ant species found was Myrmelachista gallicola Mayr (Formicinae), including a single queen and larvae individuals. Galls occupied by these ants were 11.5% larger compared to unoccupied galls (gall diameter: occupied galls - 10.00 ± 2.09 mm; unoccupied galls - 8.97 ± 1.90 mm). Abandoned galls might promote the diversity of other organisms, especially for opportunistic dwellers such as ants.

Fine-scale habitat heterogeneity favours the coexistence of supergene-controlled social forms in Formica selysi

Background Social insects vary widely in social organization, yet the genetical and ecological factors influencing this variation remain poorly known. In particular, whether spatially varying selection influences the maintenance of social polymorphisms in ants has been rarely investigated. To fill this gap, we examined whether fine-scale habitat heterogeneity contributes to the co-existence of alternative forms of social organization within populations. Single-queen colonies (monogyne social form) are generally associated with better colonization abilities, whereas multiple-queen colonies (polygyne social form) are predicted to be better competitors and monopolize saturated habitats. We hypothesize that each social form colonizes and thrives in distinct local habitats, as a result of their alternative dispersal and colony founding strategies. Here, we test this hypothesis in the Alpine silver ant, in which a supergene controls polymorphic social organization. Results Monogyne and polygyne colonies predominate in distinct habitats of the same population. The analysis of 59 sampling plots distributed across six habitats revealed that single-queen colonies mostly occupy unconnected habitats that were most likely reached by flight. This includes young habitats isolated by water and old habitats isolated by vegetation. In contrast, multiple-queen colonies were abundant in young, continuous and saturated habitats. Hence, alternative social forms colonize and monopolize distinct niches at a very local scale. Conclusions Alternative social forms colonized and monopolized different local habitats, in accordance with differences in colonization and competition abilities. The monogyne social form displays a colonizer phenotype, by efficiently occupying empty habitats, while the polygyne social form exhibits a competitor phenotype, thriving in saturated habitats. The combination of the two phenotypes, coupled with fine-scale habitat heterogeneity, may allow the coexistence of alternative social forms within populations. Overall, these results suggest that spatially varying selection may be one of the mechanisms contributing to the maintenance of genetic polymorphisms in social organization.

Kraliçe (Ana) Arı Kalitesini Etkileyen Faktörler

The basic rule in honeybee (Apis mellifera L.) rearing is to work with qualified queens. Quality queen means strong and healthy colonies. Honey bee colonies are a social community, each managed by a single queen bee. The queen bee is the only female that produces eggs in the colony under normal conditions, and the quality and healthy queen is important for the continuity of the colony. Many factors affect the quality of the queen bee, such as the rearing colony, the age of the transferred larva and the transfer medium, the season, cell emergence weight, spermatheca charged, the characteristics of the starter and finisher hives. In this paper, the issues to be considered in raising a quality queen are emphasized.

Cooperation with non-kin: Context-dependent acceptance of alien queens by polygynous ant workers

Relatedness underlies the evolution of reproductive altruism, yet eusocial insect colonies occasionally accept unrelated reproductive queens. To better understand this seemingly paradox, we investigated whether acceptance of unrelated queens by workers is an incidental phenomenon resulting from failure to recognize non-nestmate queens, or whether it is an adaptive behavior favored in specific contexts where cooperation is preferable to rejection. Our study system is the socially polymorphic Alpine silver ant, Formica selysi. Within populations some colonies have a single queen (monogynous), and others have multiple, sometimes unrelated, breeding queens (polygynous). Social organization is determined by a supergene with two haplotypes. In a first experiment we investigated whether workers from polygynous colonies were inherently more prone to accepting unrelated queens than workers from the alternate, monogynous social form. We found that workers rejected all alien queens, independently of their social origin and of the number of queens heading their colony. We then investigated whether queen acceptance was favored in specific conditions. We found that workers from polygynous colonies accepted alien queens when these queens were accompanied by workers. These results show that workers flexibly adjust their acceptance of alien queens according to the situation. We discuss how conditional acceptance of unrelated queens may be adaptive by providing benefits through increased colony size and/or genetic diversity, and by avoiding the rejection costs resulting from fighting.

Kin Selection: My Sister’s Keeper

Female bees carry two sets of chromosomes, one from the mother, one from the father—they are diploid. Male bees (drones) carry only one set, inherited from the mother—they are haploid. As a result, the relation between sisters is closer than between a female worker and her possible offspring. This inheritance structure led to the caste scheme of bee colonies, with a single queen giving rise to all offspring, while the sterile female workers take over the child care, not having children of their own. By assuring the survival of the children of the queen, the worker females assure the passage of favorable genes better than by having children of their own.

Winter is coming: harsh environments limit independent reproduction of cooperative-breeding queens in a socially polymorphic ant

Cooperative breeding animals frequently inhabit harsh environments. It is widely accepted that harsh environments hinder independent reproduction, and this constraint maintains individuals in family groups. Yet the assumption that harsh ecological conditions reduce the success of members of cooperative breeding groups when breeding independently has not been experimentally tested. We addressed this shortcoming using the socially polymorphic Alpine silver ant, Formica selysi . This species has single-queen (independent breeders) and multiple-queen (cooperative breeders) colonies coexisting within populations. We placed newly mated queens emerging from each type of colony to breed alone in either a harsh or mild winter condition and recorded their brood production and survival. Queens emerging from single-queen colonies were unaffected by the winter condition and were more successful at founding a nest independently than queens from multiple-queen colonies. By contrast, queens from multiple-queen colonies had higher mortality after a harsh than after a mild winter. These results support the long-held assumption that harsh environments constrain independent reproduction of members of cooperative breeding groups.

Rediscovery of Crematogaster subgenus Colobocrema (Hymenoptera, Formicidae) in Southeast Asia

The Crematogaster subgenus Colobocrema was established to include the single species C. cylindriceps Wheeler, based on a single queen from the Philippines. We discovered a species close to or the same as C. cylindriceps in Borneo and provide descriptions of the queen, worker and male. This species lives in live climber plants of secondary and primary rainforests. The phragmotic morphology characterising the queen caste is considered an adaptation to a stem-inhabiting life style.