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Several lines of evidence support genetic links between ovary size and division of labor in worker honey bees. However, it is largely unknown how ovaries influence behavior. To address this question, we first performed transcriptional profiling on worker ovaries from two genotypes that differ in social behavior and ovary size. Then, we contrasted the differentially expressed ovarian genes with six sets of available brain transcriptomes. Finally, we probed behavior-related candidate gene networks in wild-type ovaries of different sizes. We found differential expression in 2151 ovarian transcripts in these artificially selected honey bee strains, corresponding to approximately 20.3% of the predicted gene set of honey bees. Differences in gene expression overlapped significantly with changes in the brain transcriptomes. Differentially expressed genes were associated with neural signal transmission (tyramine receptor, TYR) and ecdysteroid signaling; two independently tested nuclear hormone receptors (HR46 and ftz-f1) were also significantly correlated with ovary size in wild-type bees. We suggest that the correspondence between ovary and brain transcriptomes identified here indicates systemic regulatory networks among hormones (juvenile hormone and ecdysteroids), pheromones (queen mandibular pheromone), reproductive organs and nervous tissues in worker honey bees. Furthermore, robust correlations between ovary size and neuraland endocrine response genes are consistent with the hypothesized roles of the ovaries in honey bee behavioral regulation. [ABSTRACT FROM AUTHOR]

Wolbachia is a widespread maternally transmitted endosymbiotic bacteria with diverse phenotypic effects on its insect hosts, ranging from parasitic to mutualistic. Wolbachia commonly infects social insects, where it faces unique challenges associated with its host's caste-based reproductive division of labor and colony living. Here, we dissect the benefits and costs of Wolbachia infection on life-history traits of the invasive pharaoh ant, Monomorium pharaonis, which are relatively short lived and show natural variation in Wolbachia infection status between colonies. We quantified the effects of Wolbachia infection on the lifespan of queen and worker castes, the egg-laying rate of queens across queen lifespan, and the metabolic rates of whole colonies and colony members. Infected queens laid more eggs than uninfected queens but had similar metabolic rates and lifespans. Interestingly, infected workers outlived uninfected workers. At the colony level, infected colonies were more productive as a consequence of increased queen egg-laying rates and worker longevity, and infected colonies had higher metabolic rates during peak colony productivity. While some effects of infection, such as elevated colony-level metabolic rates, may be detrimental in more stressful natural conditions, we did not find any costs of infection under relatively benign laboratory conditions. Overall, our study emphasizes that Wolbachia infection can have beneficial effects on ant colony growth and worker survival in at least some environments., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2024. Published by The Company of Biologists Ltd.)