Survival potential of the Mediterranean fruit fly (Ceratitis capitata) under Austrian winter conditions

Abstract: The Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann), is currently
expanding its geographic distribution to cooler, more temperate areas of Europe, where it could become an important threat to the production of various pome and stone fruits. Since 2010, the fly has been regularly detected in traps in Vienna, Austria (48.1° northern latitude), but up to now, it is not known whether it can establish permanent populations and overwinter in such an environment. In this study, the ability of C. capitata to survive the winter period in Vienna was examined over two consecutive winter seasons (2020-22). Different life stages (larva, pupa, adult) were tested for their overwintering capacity in open field conditions and in the protected environment of a basement without a heating system. Control flies were kept in a climate chamber (25 °C, 60 % RH, 14:10 L:D). Our results showed that no life stage of medfly was able to overwinter in the open field. Additionally, larvae and pupae were also unable to complete development and yield adults in the open field. In the protected environment, C. capitata survived the winter in all studied life stages. Additionally, a few surviving females laid eggs in the following fruiting season. Our data demonstrate a potential scenario in which the Mediterranean fruit fly could survive adverse outdoor conditions in regions beyond its northern range limits.