Insect pheromones are crucial for survival and reproduction because they influence insect behavior, communication, and interactions within and outside the colony. Honey bees (Apis mellifera) have one of the most complex pheromonal communication systems. One pheromone, known as Queen Mandibular Pheromone (QMP), is released by the queen bee to regulate physiology, behavior, and gene expression in the female worker caste. The pheromone acts as a signal of queen presence that suppresses worker reproduction. In the absence of reproduction, young workers focus on taking care of the queen and larvae, known as nurse tasks, while older workers forage. In nurse bees, QMP has fundamental physiological impacts, including increasing abdominal lipid stores and increasing the protein content of hypopharyngeal glands (HPG). The HPG are worker-specific glands that can synthesize royal jelly used in colony nourishment. In workers, larger HPG signifies the ability to secrete royal jelly, while shrunken glands are characteristic of foragers that do not make jelly. While it is known that QMP increases abdominal lipid stores, the underlying mechanism is unclear: Does the pheromone simply make workers consume more pollen which provides lipids and protein, or does QMP also increase lipogenesis? In this study, I measured abdominal lipogenesis as fatty acid synthase (FAS) activity and monitored abdominal protein content and HPG size in caged, nurse-aged worker bees. In cages, workers were exposed to QMP or not, and they were provided with a lipid less diet in a full factorial design experiment. I found that QMP did not influence abdominal FAS activity or protein, but significantly increased HPG size. The data also revealed a significant positive correlation between abdominal protein and HPG size. My results do not support the idea that QMP modulates lipogenesis in worker bees, but my data can be interpreted to reflect that QMP mobilizes abdominal protein for the production of jelly in the HPG. This finding is in line with a previous study revealing a role of honey bee Brood Pheromone in mobilization of a major protein used in jelly production. Overall, my results support a fundamental role of QMP in worker metabolic processes associated with colony nourishment.
The objective of this experiment is to study a colony’s seed preference following previous exposure to a seed type in the seed harvester ant Pogonomyrmex californicus. It was hypothesized that foragers would demonstrate a measurable preference for the seed type they had previously experienced over the novel seed type. The cuticular hydrocarbon profile is suspected to be an influence in the foragers’ seed selection. Following an incubation period with the designated seed type, a series of preference trials were conducted over the course of two days for two experiments in which each colony fragment was given a seed pile with a 1:1 ratio of niger and sesame, after which any seeds moved off the seed pile were determined to be chosen, as well as if the workers were observed moving the seeds off the pile from the video recordings. Using video recordings, the seed selections of individual foragers were also tracked. The results partially support the hypothesis, however, in some cases, the ants did not collect enough seeds for the preference to be significant, and not all colony fragments had preferences that lined up with what they had previously experienced according to their treatment. Familiarity with the hydrocarbon profile of the seed type the colony had experienced is a possible proximal explanation for why colonies had seed preferences that aligned with their treatment, the seed they were designated to experience. Due to the low quantity of seeds collected during preference trials, seed preference amongst individual foragers remains unclear due to many different foragers selecting a seed during only one trial, with very few foragers returning to forage for seeds over the course of the experiment.