Insights on the nutritional ecology of a nocturnal pollinating insect.

Abstract

Nutritional ecology examines the environmental effects on nutritional needs, food intake and foraging behaviors, and the use of nutrients ingested by animals. Adults of many insects' species feed on nectars rich in sugars allowing them to match the nutritional needs necessary for reproduction. Among insects, Lepidoptera are often considered opportunistic foragers that visit a wide variety of available flowers, although with some preferences. While nutritional ecology of diurnal Lepidoptera is beginning to be explored, very little work focuses on nocturnal species because they are complicated to study in the wild. To address this, we used new laboratory approaches to study feeding behaviors (number and duration of visits to artificial flowers, food preferences associated with the texture and odors of the flowers) as well as gustatory detection by antennae (proboscis extension reflex) in the male crop pest moth Agrotis ipsilon. We showed that (i) food responsiveness is age-dependent and increases mainly with sugar quantity and marginally with sugar quality, (ii) diet quality impacts feeding behaviors in the first days of adulthood, and (iii) male moths choose their food through floral cues. Taken together, these data allow to define this species as a generalist forager with a preference for flowers with sugary nectars rich in sucrose, fructose, and glucose. Our results thus provide considerable information on the close links between food sources and nutritional ecology in this species, which is important for guiding future studies on their behavioral ecology, population dynamics, as well as for population monitoring and for regional pest management.