BACKGROUND
Classical biological control has been identified as the most promising approach to limit the impact of the invasive pest species
Halyomorpha halys (Heteroptera: Pentatomidae). This study investigated the parasitism rate at sites where the biocontrol agent
Trissolcus japonicus (Hymenoptera: Scelionidae) was released and where its unintentional introduction took place, in the Trentino–South Tyrol region. The effect of land-use composition was studied to understand which factors favor the establishment of hosts and parasitoids, including native and exotic species.
RESULTS
The released
T. japonicus were detected a year after the start of the program, with a significant parasitoid impact and discovery, compared to control sites.
Trissolcus japonicus was the most abundant
H. halys parasitoid, and
Trissolcus mitsukurii and
Anastatus bifasciatus were recorded also. The efficacy of
T. mitsukurii was lower in sites where
T. japonicus was successfully established, suggesting a possible competitive interaction. Parasitism level by
T. japonicus at the release sites was 12.5% in 2020 and 16.4% in 2021. The combined effect of predation and parasitization increased
H. halys mortality up to 50% at the release sites. Landscape composition analysis showed that both
H. halys and
T. japonicus were more likely to be found at sites with lower altitude and with permanent crops, whereas other hosts and parasitoids preferred different conditions.
CONCLUSION
Trissolcus japonicus showed a promising impact on
H. halys, at release and adventive sites, with minor nontarget effects, mediated by landscape heterogeneity. The prevalence of
T. japonicus in landscapes with permanent crops could support IPM in the future. © 2023 The Authors.
Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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