Torymus sinensis: Biology, host range and hybridisation

Quacchia, Ambra; Askew, Richard; Seeichi, Moriya; Schonrogge, Karsten. 2013 Torymus sinensis: Biology, host range and hybridisation. [Lecture] In: International Society for Horticultural Science - ISHS II. European Congress on Chestnut, Debrecen, Hungary, 9-12 October 2013. (Unpublished)

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Torymus sinensis is a solitary ectophagous parasitoid of the chestnut gallwasp, Dryocosmus kuriphilus. It originates, like its host, from China. Following the accidental introduction and rapid range expansion of the pest in Japan (in the 40s),USA (70s) and Italy (2000s), T. sinensis was introduced into these countries as a biological control agent. While its effectiveness in controlling the pest was confirmed in Japan, and recently in Italy, some aspects of its biology are still unknown or at most scarcely investigated. Preliminary tests were performed in order to investigate some important aspect of its biology. The rearing of D. kuriphilus galls over 2 years revealed a second emergence period of T. sinensis adults. About 3% of a cohort showed such prolonged diapause. Extended diapause is an extremely rare strategy among oak gall parasitoids, most of which are polyphagous on the oak gall community. T. sinensis, in contrast, is specific to apparently only one host species, the gallinducer D. kuriphilus, and if the availability of D. kuriphilus galls were to be unpredictable, extended diapausing might be expected to be selected. Extended diapause also makes T. sinensis a better biocontrol agent because local populations are more likely to survive temporary extinction of the host population. Tests on the host range of T. sinensis were performed using 7 species of oak gallwasps which occur at similar times in the field to D. kuriphilus: Andricus crispator, A. curvator, A. cydoniae, A. grossulariae, A. multiplicatus, Biorhiza pallida and Dryocosmus cerriphilus. Few and brief ovipositor prickings were observed on A. cydoniae, B. pallida and D. cerriphilus but no eggs were laid. These data confirm the host gall specificity of T. sinensis in Europe. In order to assess the probability of hybridization of the introduced parasitoid with native European Torymus species, mate recognition was tested using 4 native species: T. flavipes, T. auratus, T. affinis and T. geranii. The natural mating behaviour of T. sinensis involves a “dance” with the male approaching the female and shaking its wings and swaying the body. No mate recognition was recorded using the native species. Although mating behaviour like the one shown by T. sinensis could make cross breeding less likely, it is important to note that the native species tested are difficult to mate under controlled conditions in any event, and other species, such as T. notatus and T. cyaneus (more closely related to T. sinensis) should also be tested.

Item Type: Publication - Conference Item (Lecture)
Programmes: CEH Topics & Objectives 2009 - 2012 > EHFI
UKCEH and CEH Sections/Science Areas: Pywell
Additional Keywords: Biological invasions
NORA Subject Terms: Ecology and Environment
Date made live: 27 Mar 2014 16:15 +0 (UTC)

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