Torymus sinensis: biology, host range and hybridization

Torymus sinensis is a parasitoid of the chestnut gall wasp Dryocosmus kuriphilus, introduced as a biological control agent into Japan, USA, and since 2005, into Europe. Although its effectiveness in controlling the pest was confirmed, some important aspects of its biology, including risks to non-target species, are still unknown or at most scarcely investigated. The results of the present study address an important aspect of the life-cycle of T. sinensis: the existence of extended diapause. Behavioural experiments confirm high levels of host specificity by the parasitoid and suggest that interbreeding with native Torymus species is highly unlikely.