Effects of nutritional deprivation on development and behavior in the subsocial bee Ceratina calcarata (Hymenoptera: Xylocopinae)

AbstractBy manipulating resources or dispersal opportunities, mothers can force offspring to remain at the nest to help raise siblings, creating a division of labor. In the subsocial bee Ceratina calcarata, mothers manipulate the quantity and quality of pollen provided to the first female offspring, producing a dwarf eldest daughter that is physically smaller and behaviorally subordinate. This daughter forages for her siblings and forgoes her own reproduction. To understand how the mother’s manipulation of pollen affects the physiology and behavior of her offspring, we manipulated the amount of pollen provided to offspring and measured the effects of pollen quantity on offspring development, adult body size and behavior. We found that by experimentally manipulating pollen quantities we could recreate the dwarf eldest daughter phenotype, demonstrating how nutrient deficiency alone can lead to the development of a worker-like daughter. Specifically, by reducing the pollen and nutrition to offspring, we significantly reduced adult body size and lipid stores, creating significantly less aggressive, subordinate individuals. Worker behavior in an otherwise solitary bee begins to explain how maternal manipulation of resources could lead to the development of social organization and reproductive hierarchies, a major step in the transition to highly social behaviors.Pollen manipulation- dataset pollen consumed and head width and development dataEarly stage larvae and eggs were removed from nests, weighed using a Mettler analytical balance (accuracy 0.01 mg) and randomly assigned to a control group or one of two treatment groups. The pollen of the control group remained unmanipulated. For the treatment groups, approximately 1/3 of the pollen ball was removed from one group and added to the other group. Both treatment groups were reweighed and offspring and pollen ball were placed in PCR tubes in the incubator at 25°C with 50% humidity until reaching their final molt. Offspring from later developmental stages were raised in the incubator as additional controls. Every other day, the development of the offspring was assessed. The head width and sex were recorded for all brood that reached adulthood. Sex was determined by counting the number of metasomal terga; females have six segments, while males have seven (Rehan and Richards, 2010a). To quantify the exact amount of pollen consumed, we calculated the amount of pollen provided minus the amount of pollen remaining whe