The point about the fight against the bedbug with the samurai wasps


2020 was a very important year in the fight against the Asian bedbug, not only in Trentino, but in all regions of Northern Italy. The national biological control program, approved by decree of the Ministry of the Environment, in fact provided for the release into nature of the species Trissolcus japonicus as a Biological Control Agent of the phytophagus Halyomorpha halys.

For the province of Trento, the breeding and multiplication during the spring and the release of the antagonist during the summer were handled by the Edmund Mach Foundation, which worked in close coordination with the CREA Difesa e Certificazione, which prepared the feasibility study of the project.
The preliminary results of the monitoring and the integration of the risk study have already been transmitted, in agreement with the regional / provincial phytosanitary services involved, to the Ministry of the Environment and the Protection of the Territory and the Sea by 2020 and their evaluation. the renewal of the authorization to launch the antagonist for the current year will result.
And while the vespina is being raised on the San Michele campus in anticipation of next summer's launches, now it's time for the group working on the PAT-funded SWAT project to further process the post-release monitoring data, which they point out a good settlement of the samurai wasp, whose presence was detected after the launches in 30% of the 20 Trentino sites, a promising result and beyond expectations for this first year.

Preliminary results of post release monitoring of wasps
Preliminary results confirm the efficacy of released individuals in locating and parasitizing Asian bedbug eggs and spreading across the territory. Furthermore, no parasitizations were observed on other species. The use of the antagonist wasp in the field coincided with an overall good year for the management of the bedbug in apple orchards: compared to 5.7% of fruit damaged in 2019, the number fell in 2020 to 1.7% .
For years at the forefront of addressing this emergency, thanks to the recent regulatory opening that allows the use of parasitoids, the FEM has therefore finally been able to implement the biological control program, although it will take a few years to reach a balanced situation.
The launches of the microvespe: calendar and maps studied in detail
The release map was carefully studied by FEM researchers who predicted three releases in the selected areas, between June and August. About 100 females and 10 males were released at each point and for each release.
Intense breeding since last spring: 25,000 individuals of bedbugs and 13,000 wasps
The samurai microwives bred for the releases belong to the strain provided by CREA and the operation was made possible thanks to the breeding that lasted months at the FEM facilities of 25,000 adult individuals of bedbugs, of which over 18,000 delivered by volunteer citizens, this allowed to produce about 4,700 eggs which were used to multiply the vespina. The vespine bred are 13 thousand. Each T. japonicus female is capable of producing around 80 eggs. The wasp, which reproduces at the expense of its host by laying its eggs inside the eggs of the Asian bug, is absolutely harmless for humans and other organisms.
The publication "Biological fight against the Asian bedbug"
Fresh off the press, this publication edited by the Technology Transfer Center is inspired by the experience gained in this first year of activity, and aims to transmit to operators, technicians and farmers some basic concepts on which biological control is based. The different methods of intervention that fall within the general definition of biological control are described, highlighting its advantages and limits, illustrating the ecological characteristics of the contexts in which one must operate in order to be successful.

To download the in-depth monographic study:

More information on the website

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