Trichopria drosophilae (Perkins) (Hymenoptera: Diapriidae) is a pupal parasitoid of drosophila flies recorded from
several parts of the world. It is currently considered for augmentative biological programs to control the severe
agricultural pest Drosophila suzukii (Matsumura) (Diptera: Drosophilidae). Since D. suzukii has invaded regions
that experience zero and sub-zero winter temperatures, cold tolerance of the parasitoid is an important aspect to
consider. We characterized low temperature tolerance and overwintering capacity of a colony of T. drosophilae
collected in Northern Switzerland. We used copper-constantan thermocouples to determine the supercooling
point and pre-freeze mortality. Moreover, we subjected honey-fed and unfed adult T. drosophilae as well as
developing stages within their drosophila host to short- and long-term acclimation conditions and assessed the
duration of their survival at low temperatures. Finally, we exposed adult and sub-adult stages to winter conditions
in a semi-field experiment and evaluated their survival. We found that T. drosophilae is chill susceptible
like D. suzukii, but adults froze and survived at colder temperatures than those reported for D. suzukii. Adult
parasitoids could tolerate several days of exposure to sub-zero temperatures and could reproduce afterwards,
whereas sub-adult stages could survive longer periods under these conditions. The provision of honey and water
enhanced the survival of adults and long-term acclimation led to longer survival in all stages. The semi-field
experiment supported the results of the laboratory tests. Based on these results we suggest that in Central
Europe, T. drosophilae survives winters mainly in developing stages but adults are likely able to tolerate short
periods of low spring temperatures.