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Winter survival of the granary weevil Sitophilus granarius and the parasitoid Lariophagus distinguendus in a simulated grain store

Hansen, Lise Stengård, Skovgård, Henrik
BioControl 2010 v.55 no.6 pp. 711-718
Lariophagus distinguendus, Sitophilus granarius, ambient temperature, biological control, cold, grain storage facilities, overwintering, parasitoids, spring, temperate zones, winter
The parasitoid Lariophagus distinguendus Förster (Hymenoptera: Pteromalidae) is a promising candidate for biological control of the granary weevil Sitophilus granarius (L.) (Coleoptera: Curculionidae) in grain stores. For practical application in northern temperate regions it is important that the parasitoids can survive the cold temperatures in the grain during the winter and resume activity the following spring. In the present study the survival of Lariophagus distinguendus and Sitophilus granarius was followed during a simulated winter with stepwise reductions of temperature down to 6°C which was maintained for 15 weeks. Only 20% of the weevils were alive after eight weeks at 6°C, whereas the survival of L. distinguendus was unaffected by the temperature decrease. After being returned to room temperature an F ₁ generation of the parasitoid emerged and was able to reproduce.