Reproductive parasitism by worker honey bees suppressed by queens through regulation of worker mandibular secretions

Abstract

Social cohesion in social insect colonies can be achieved through the use of chemical signals whose production is caste-specific and regulated by social contexts. In honey bees, queen mandibular gland pheromones (QMP) maintain reproductive dominance by inhibiting ovary activation and production of queen-like mandibular gland signals in workers. We investigated whether honey bee queens can control reproductively active workers of the intraspecific social parasite Apis mellifera capensis, parasitising A. m. scutellata host colonies. Our results show that the queen’s QMP suppresses ovarian activation and inhibits the production of QMP pheromone signals by the parasitic workers, achieved through differential expression of enzymes involved in the biosynthesis of these pheromones at two points in the biosynthetic pathway. This is the first report showing that honey bee queens can regulate reproduction in intraspecific social parasites and deepens our understanding of the molecular mechanisms involved in the regulation of worker reproduction in social insects.

Turning workers into false queens– the role of exogenous pheromones in regulating reproduction in worker honey bees

“…This effect was seen not only in A. m. scutellata, whose workers do not produce significant amounts of 9-ODA (Zheng et al, 2010), but also in workers of A. m. capensis clones, which are known to produce queen-like pheromonal components from their MDG (Crewe and Velthuis, 1980). Recently, a study by Mumoki et al (2018) demonstrated that honey bee queens can control the synthesis of MDG pheromones in reproductively active workers by blocking the production of alcohol dehydrogenase, the enzyme responsible for the oxidative reduction of 9-HDA into the queen substance (9-ODA). Thus, this explains why only false queens were able to produce queen-like signals in comparison with non-pheromone carriers.…”

Expression of honey bee (Apis mellifera) sterol homeostasis genes in food jelly producing glands of workers

“…In total, eight genes that have been shown to be either stably expressed in other A. mellifera subspecies or hybrids under similar conditions (A. mellifera unknown subspecies, Germany (Dobritzsch et al, 2019;Winkler et al, 2018); Apis mellifera ligustica hybrids, Republic of Korea (Jeon et al, 2020;Moon et al, 2018), or that have been shown to be stably expressed in A. mellifera scutellata heads (South Africa (Mumoki et al, 2018)) were tested for their suitability as reference genes. However, none of these genes was expressed with a C q value standard deviation (SD) lower than 1 (Buttstedt et al, 2023a) and thus they were all considered as inconsistent (Pfaffl et al, 2004).…”

Genetic basis of chemical communication in eusocial insects

“…2). For example, the cape honeybee A. mellifera capensis develops the ability to reproduce in the absence of the host queen pheromone QMP, which is accompanied by changes in pheromone production (Mumoki et al 2018). During the transition to reproductive status, the alcohol dehydrogenase (ADH) that converts 9-HDA to 9-ODA (QMP) is dramatically up-regulated in the mandibular gland (five times higher in queenless workers compared with queenright workers).…”