Nuances in diet quality and quantity influence phenotypic dimorphism during honey bee (Apis mellifera) caste determination

Nutrition intake during the larval stage of holometabolous insect’s influences and fuels growth throughout metamorphosis. In social insects, differences in larval nutrition can regulate a profound reproductive division of labor. Provisioning by nurse bees differs between worker-destined and queen-destined larvae, and drives caste determination. Many studies have evaluated the dietary factors determining caste, but these previous studies seem to conflict as to whether diet quantity or quality drive caste determination. Because nutritional factors determining queen-worker caste is enigmatic, a study with careful quantity and quality manipulation is needed. We evaluated both dietary quantity and quality on phenotypic dimorphism by using the geometric framework. This powerful method gauges the interactions among nutritional components and allows us to evaluate if either specific dietary components, or multiple dietary interactions, determine caste in honey bees. Using in vitro rearing, we manipulated diet by varying both the macronutrient and quantity components. By following bees to eclosion, we were able to evaluate phenotypic differences between castes such as number of ovariole number, weight , spermetheca size, mandible structure, basitarsus, width and length of head. We then used a principal component analysis (PCA) to classify these bees as queens, workers or intercastes by comparing to hive bees. This research not only allows us to further research the cellular mechanisms involved in caste determination, but also we can further study the physiology of both workers and queens.