The effect of diet on the development of pheromone signals in Apis mellifera scutellata workers

Abstract

The social organization of honey bee colonies is predominantly controlled by the pheromonal cues produced by the queen, workers and brood. Pheromone composition is dependent on the social environment, context, audience and physiological status of the individual. In the absence of the queen, ontogenic changes and reproductive status modulate pheromone production and composition in workers. In these queenless workers, pheromonal status influences diet with dominant workers consuming less pollen than subordinates as they are fed protein jelly through trophallaxis, which positively correlates with their ovarian activation. However, it is not known to what extent diet affects pheromonal status in queenless workers. To investigate whether diet affects the production of glandular signals, Apis mellifera scutellata workers were fed carbohydrate-only or protein-rich diets for twenty-five days. The mandibular and tergal gland secretions were analyzed using gas chromatography and the ovarian activation statuses were evaluated. A clear link between diet and pheromone profiles was observed with workers fed a protein-rich diet producing mandibular gland chemical profiles more typical of queens. The effect of diet on tergal gland chemical profiles was less distinct, but a shift from fatty acid to n-alkane components was seen in the older workers irrespective of diet, most likely due to ontogeny. Though mandibular gland profiles were queen-like with high proportions of 9-HDA, the levels of 9-ODA remained in the range of non-reproductive workers and the ovaries were not fully activated. This suggests that diet could prime queenless workers to become false queens, but do not trigger the transformation into false queens.