Oviposition strategies in butterflies and consequences for conservation

Sammanfattning: Oviposition strategies are an important component of life history evolution in insects. Oviposition is a complex behaviour, where females must locate suitable habitat patches, locate oviposition sites, evaluate the quality, and finally decide how many eggs to lay. In this thesis, I explore some factors that may influence oviposition strategies in female butterflies. It discusses oviposition strategies from large to fine scales and ends with a discussion on implications for conservation. In paper I we tested for local adaptations in oviposition preference and larval performance in Polyommatus icarus. The result suggests that this species is evolutionary conservative in its utilization of the tested host plants. In the second paper we investigated frequency-dependent host plant choice in Polygonia c-album and showed that females spent significantly more time, and laid more eggs, in patches with high frequency of the preferred host. The influence of nectar sources on host plant choice in P. icarus was tested in paper III, females preferred ovipositing on host plants with flowers and after feeding. In paper IV we investigated oviposition “mistakes” in P. c-album and found differences in discrimination of hosts and non-hosts. Further, we showed that P. c-album butterflies are capable of responding to host quality by increasing clutch sizes on a high ranked host (paper V). Finally, in paper VI I explored how female oviposition behaviour can influence habitat management for a threatened butterfly species, Parnassius mnemosyne, by doing an observational field study on oviposition site preferences. This thesis highlights oviposition as a stepwise process and show that female discrimination is important at a multitude of levels with implications for oviposition strategies.