Does larval food affect cuticular profiles and recognition in eusocial bees? a test on Scaptotrigona gynes (Hymenoptera: Meliponini)

Abstract

The relative contributions of heritable and environmentally acquired components of colony odor towards individual recognition are scarcely known in social insects. Larval food may affect cuticular profiles which in turn may serve as cues in the process of elimination of excess gynes characteristic of the eusocial stingless bees. In this study, we evaluated the contribution of larval food to cuticular profiles of stingless bee gynes and quantitatively tested if recognition (latency) from workers may be related to gyne chemotype and origin in the species Scaptotrigona pectoralis. Our results showed that the origin of food did not significantly affect the cuticular profiles of gynes, as larvae of the same origin reared on food from different colonies showed similar cuticular profiles at emergence. We suggest that overlapping over floral resources may account for the similarity in cuticular cues derived from food across experimental colonies. Additionally, workers showed similar latency time to first aggression towards gynes irrespectively of their chemotype and origin. Gyne’s mass had no effect on the aggressive response from workers either. We observed that gynes threatened aggressive workers which counteracted further aggression. Our results indicate that in stingless bees, cuticular hydrocarbons at emergence seem to have genetic origin and that gyne tolerance seems not related to cuticular chemical profiles. We suggest that cuticular cues may serve as caste labels for the identification of newly emerged gynes after which worker aggression towards them would elicit behavioral indicators of their fitness. We studied the effect of larval food on the cuticular profile of stingless bee gynes coupled with an evaluation of the effect of chemotype in gyne recognition by workers in Scaptotrigona. We used artificial methods of gyne rearing that avoid nest odor acquisition of newly emerged individuals so that the effect of food could be better analyzed on gynes reared on food of their own colony and a different one. The origin of larval food did not significantly affect the cuticular profiles of gynes and workers attacked gynes irrespective of their chemotype. Our results demonstrate that cuticular chemical profiles are explained by genetic origin and not larval diet and that workers’ aggressive responses to gynes are independent of gyne colony origin.