Chemotactile perception and associative learning of amino acids in yellowjacket workers

Learning and memory are essential for animal survival, influencing preferences, decision-making, and foraging behaviour. In this study, we explore the perceptual and learning abilities of Vespula germanica (yellowjacket wasps) to various amino acids. We hypothesize that V. germanica can qualitatively evaluate various amino acid solutions, given their scavenging habits and the possibility of metabolizing amino acids to fuel energy. Through chemo-tactile differential conditioning, we studied worker wasp’ maxilla labium extension response (MaLER) to essential (Lysine, Tryptophan, Arginine) and non-essential amino acids (Ornithine, Aspartic acid, Glycine). Conditioning sessions included individual amino acids against water and comparisons between different amino acids. Additionally, we tested retention, discrimination, and generalization abilities, 30 minutes later with conditioned and novel stimuli. Our results show that wasps exhibit the ability to learn and discriminate various amino acids. The discrimination capacity extended to differentiating between pairs of amino acids. Memory retention was generally robust, but certain associations observed during conditioning did not persist after a 30-minute interval. Moreover, when wasps were trained with essential amino acids, the acquired learning did not generally extend to other non-essential amino acids, except for Arginine, which exhibited generalization when tested with its precursor, Ornithine. Conversely, when trained with non-essential amino acids, the acquired learning generalized to other essential amino acids. These results suggest that, unlike other hymenopterans, wasps can detect, discriminate, and generalize free amino acids, crucial for their foraging decisions. This knowledge contributes to understanding the cognitive dimensions of V. germanica and their implications for targeted pest management. Summary statement This study on Vespula germanica’ s amino acid perception enhances our understanding of foraging behaviours. The findings contribute to insect cognition studies, with potential implications for pest management.