Constancy versus flexibility in oviposition: host choice behavior in a hawkmoth

Abstract

Ovipositing insects are known to evaluate the suitability of a host plant based on innate preferences and learned information. Among these, studies on oviposition learning suggest that experienced moths might exhibit oviposition constancy, i.e. although naive moths are generalists, they ultimately lay most of their eggs on a host they have already encountered. However, whether and how these insects transition between different host species remains poorly explored. Here, we investigated the tobacco hawkmoth, Manduca sexta, with two well-known hosts (Solanaceae) and a less studied one (Martyniaceae). When investigating the oviposition behavior of freely flying moths in a large tent, we observed that hawkmoths revisited a cluster of plants several times before they searched for another host. Such revisitation behavior might be mediated by learning, reflected in an immediate increase in preference for a given plant species following prior experience with it. In addition, when the moths in the tent moved from one plant cluster to another cluster, they often targeted clusters of the same species again. Apparently, hawkmoths display some kind of oviposition constancy. However, even experienced moths occasionally targeted novel hosts, suggesting that they do not rely exclusively on a single host species and thus retain flexibility in oviposition choices.