The role of nectar sources for oviposition decisions of the common blue butterfly (Polyommatus icarus)

Neural limitations on information processing have been shown to play an important role for host plant specialization in herbivorous insects. The necessity of fast and accurate decisions favors the adoption of a few high-contrast signals, which selects against the use of multiple resources. Many species face a similar problem when searching for adult food sources and the simultaneous need to fulfill both search tasks can lead to a potential conflict. Some insects use the same host plant species for both adult and larval nutrition, which makes it possible to decrease the number of search images and thus potentially increase efficiency of the choices. The aim of this study was to investigate if there is a connection between choice of nectar sources and choice of oviposition host plant. In a laboratory experiment, females of Polyommatus icarus preferred to oviposit on Lotus corniculatus plants with flowers over those without flowers. Observations of behavioral sequences also revealed that oviposition often followed immediately after nectaring. The results suggest that nectar availability could play an important role in oviposition decisions of P. icarus and can provide one explanation to why some phytophagous insects not always choose the host plant that gives the best offspring performance.