The membrane phospholipid composition of honeybee (Apis mellifera) workers reflects their nutrition, fertility, and vitellogenin stores

Abstract

Pollen feeding in the honeybee (Apis mellifera) is dependent on the caste, ethotype, and dominance status of individuals. Pollen is the near-exclusive external source of lipids for the colony. Lipids from pollen are rich in polyunsaturated fatty acyl residues, which, because of their sensitivity to lipid peroxidation, have been suggested to limit the lifespan of individual bees. We here investigated whether the spectrum of phosphatidylcholine (PC), the main class of membrane-constituting lipids in insects, is indeed, connected to pollen feeding. We further studied the relationship between pollen feeding, PC spectra, and fat-body stores of vitellogenin, an indicator of potential longevity in bees. For this, we determined the pollen consumption, PC spectra, abdominal vitellogenin stores, and behavioral as well as reproductive status of individuals in queenless groups of workers. In contrast to earlier studies, we found that reproduction in workers is not universally linked to trophallactic dominance alone, but can be accompanied by strong pollen consumption. Pollen consumption seemed connected to a strong remodeling of tissue PC spectra. There was no systematic link between these spectra and trophallactic activity, but individuals with strongly deviating spectra also showed extreme behavioral profiles. Abdominal vitellogenin was strongly and positively linked to pollen-influenced PC spectra and the prevalence of polyunsaturated fatty acyl residues, contradicting the hypothesis that pollen consumption is systematically leading to a shorter lifespan in workers. Our results suggest that the association between pollen consumption, short lifespan, and functional sterility that differentiates workers from queens cannot in all cases be extended to the situation within the worker caste.