Appetitive learning and its exploitation in a lycaenid butterfly-ant mutualism
Masaru K. Hojo, Masaru K. Hojo
Department of Bioscience, Kwansei Gakuin University, Japan; Department of Bioscience, Kwansei Gakuin University, Japan
Communication and elaborate cognitive abilities are typical traits of social insects and are essential for various social interactions. Ants engage in mutualistic interactions with various organisms, such as plants, aphids and butterflies, by exchanging defense and nutritious rewards. In such mutualism, partner recognition and behavioral flexibility based on the inter-specific communication are important mechanisms underlying the regulation of mutualism. In a mutualistic interaction between a Pristomyrmex punctatus ant and lycaenid Narathura japonica butterfly, the ant workers learn to recognize mutualistic lycaenid caterpillars as partners by feeding on the nectars provided from the caterpillars. Caterpillar's cuticular hydrocarbons are used as a key recognition olfactory signature in this context. Furthermore, naïve workers who have interacted with learned workers also increased attending behavior to caterpillars, so they can transmit the partner information through social interactions. However, after feeding on the nectar secretions of the caterpillars, the workers modified aggressiveness, locomotor activity and brain biogenic amine levels. This suggests that the chemical signals contained in nectar secretions modify appetitive learning function of workers to enforce the cooperative behaviour.