Neuroendocrine Regulation of Reproductive Cycles in Social Insects: A Comparative Study of Honey Bee Queens and Workers

Abstract

Reproductive division of labor among social insects can be viewed as one of the most striking examples of phenotypic plasticity that is regulated by neuroendocrine pathways. The paper examined the neuroendocrine of reproductive cycles of honey bee (Apis mellifera) queen and worker with references to juvenile hormone (JH), ecdysone, and major neuropeptide. We measured hormone levels and gene expression patterns in queens and age matched workers at key times of development and reproduction over the 2023-2024 breeding seasons. The JH titers were much higher among egg laying queens (15.2 ± 2.1 ng/ul) than sterile workers (2.1 ± 0.3 ng/ul) (P < 0.001). Vitellogenin (vg) and ultraspiracle (usp) expression had a positive correlation with JH titers in queens (r = 0.87, P < 0.01) but not workers. The pars intercerebralis was differentially expressed to show differences in expression of corazonin and insulin-like peptides, which indicated a caste-specific neuroendocrine modulation. Comparative study on published data of ants (Camponotus floridanus) and wasps (Vespula vulgaris) showed that the JH-mediating pathways were conserved but neuropeptides were species-specifically regulated. Such results show that reproductive pathways in social insects are coordinated by complex neuroendocrine systems in which JH establishes a central gating hormone, and neuropeptides are caste and species specific. The study offers new information about evolutionary processes that affect reproductive division of labor, as well as new targets that may be used to control reproductive behavior in controlled pollinators. This paper offers concrete data on how it is possible to enhance the efficiency and productivity of pollination and colonies through the ability to perform specific hormonal and nutritional interventions. This neuroendocrine knowledge can be used to meet the high-levels of bee management, selective breeding, and sustainable agricultural systems of pollination.