Torymus sinensis: a viable management option for the biological control of Dryocosmus kuriphilus in Europe?

Abstract

The chestnut gall wasp Dryocosmus kuriphilus is a global pest of chestnut (Castanea spp). Established as a pest in the mid-twentieth century in Japan, Korea and North America, this species was first reported in Europe in 2002. Following the successful release of a biological control agent Torymus sinensis in Japan, this parasitoid species has been released in Italy since 2005. Here we discuss the potential of T. sinensis as a viable management option for the biological control of D. kuriphilus in central Europe. We suggest that more consideration should be given to determining, (i) the conditions under which T. sinensis may attack alternative native gall wasp hosts and (ii) the likelihood of hybridization of this species with native Torymus. Both issues are central to predicting unassisted range expansion by released T. sinensis, and to assess the environmental risks associated with a more widespread release of this species in Europe.

Detecting arthropod intraguild predation in the field

“…An overview of the current ERA procedure and definitions of risk categories are given in Fig. 1 and Table 1 of Gibbs et al 2011. The techniques here can be used in the context of an environmental risk assessment before or after the release of a BCA.…”

“…Firstly, providing data on all aspects of an ERA is time consuming and costly. Secondly, direct and indirect effects of a BCA on the environment (see Gibbs et al 2011 for a definition) embrace complex aspects of its own biology and interactions with native non-target species. Thirdly, and perhaps the biggest challenge, is the lack of a globally harmonized regulation for the release of BCAs among countries.…”

“…In current ERA schemes all these major ecological processes are handled as a single question in the procedure, in a generic ''black-box'' approach (see Fig. 1 in Gibbs et al 2011). There is an urgent need to develop strategies for assessing these important different issues.…”

Biological Control of the Invasive Dryocosmus kuriphilus (Hymenoptera: Cynipidae) - an Overview and the First Trials in Croatia

“…Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipide) is globally invasive species and considered as one of the most damaging pests of sweet chestnuts [4]. During its expansion into new territories it has shown all the typical traits of an invasive species: easy establishment, quick spread and damage [5,6]. It was first recorded in Croatia in 2010 [7] in Istria and Zagreb area and it spread very quickly to other parts of Croatia [8].…”

“…Classical biological control using parasitoid Torymus sinensis Kamijo (Hymenoptera: Torymidae) has been proven to be the only effective method of controlling the populations of D. kuriphilus and has been successfully applied in Japan, South Korea, the USA and Italy [6,16,[22][23][24][25].…”