Pupal and Adult Experience Affect Adult Response to Food Odour Components in the Flower-Visiting Butterfly Tirumala limniace

Simple Summary: Butterfly larvae and adults can sense food odours from their surroundings, and exposure to these odours could alter larval or adult feeding preferences. However, it is still unknown whether butterfly pupae can sense odours from their surroundings. And little is known about how flower scents, in combination with food, affect butterfly adults' subsequent foraging behaviour. Tirumala limniace (Lepidoptera: Danaidae) is a flower-visiting and highly charismatic butterfly. In this study, T. limniace pupae were exposed to the odour alpha-pinene and adults were exposed to the odours alpha-pinene and ethyl acetate to examine the effect of the experience on the foraging behaviour of T. limniace. The results showed that exposure of T. limniace pupae to alpha-pinene affected the feeding preference of newly emerged adults. T. limniace exhibits olfactory learning in the adult stage, and adult odour preferences are correlated with the frequency of their training, though an increased training time does not necessarily imply an enhanced learning ability. Unlike some studies in other systems, we found that T. limniace males learned odours faster than females. This may be due to differences in antennal sensilla, affecting sensitivity to odours and nectar demand between males and females. Our study can help elucidate the important role of learning behaviour in butterfly adaptive responses to the environment and lay the foundation for further research on butterfly learning and memory. Butterflies have the ability to learn to associate olfactory information with abundant food sources during foraging. How the co-occurrence of both food and food odours affects the learning behaviour of adults and whether butterflies perceive the odour of their surroundings and develop a preference for that odour during the pupal stage have rarely been tested. We examined the effect of experience with food odour components (alpha-pinene and ethyl acetate) during the pupal and adult stages on the foraging behaviour of the flower-visiting butterfly Tirumala limniace. We found that alpha-pinene exposure during the pupal stage changed the foraging preference of newly emerged adults. T. limniace exhibits olfactory learning in the adult stage, and adult learning may influence their previous pupal memory. Moreover, adults' odour preference did not continue to increase over multiple training times. The learning ability of adults for floral odours (alpha-pinene) was greater than that for non-floral odours (ethyl acetate). In contrast to previous studies, we found that males learned odours more efficiently than females did. This could be attributed to differences in antennal sensilla, affecting sensitivity to compounds and nectar demand between males and females. Our study provides further insight into how olfactory learning helps flower-visiting butterflies use food odours to forage better.