Stahl Judith M, Babendreier Dirk, Marazzi Cristina, Caruso Stefano, Costi Elena, Maistrello Lara, Haye Tim
CABI, Rue des Grillons 1, 2800 Delémont, Switzerland.
Institute of Ecology and Evolutionary Biology, University of Bremen, Leobener Str. NW2, 28359 Bremen, Germany.
Insects. 2019 Apr 15;10(4):108. doi: 10.3390/insects10040108.
The generalist egg parasitoid (Geoffroy) (Hymenoptera: Eupelmidae) is the most prevalent egg parasitoid of the invasive (Stål) (Hemiptera: Pentatomidae) in Europe. To assess its efficacy against the pest and to validate the potential risks for non-target species in a realistic field setting, inundative releases were conducted over three consecutive years in four fruit orchards in Switzerland and Italy. In total, more than 4300 females were released, which was equivalent to 11,000 to 26,000 females per hectare, depending on distances between trees in each orchard. Parasitism of freeze-killed sentinel eggs achieved with the current release strategy was on average 6% (range: 2%-16%) and considered not high enough to effectively suppress the pest. However, the overall impact of on the mortality of eggs was likely underestimated. If pre-imaginal parasitoid mortality (3.3%) and host feeding (6%) are added to the observed parasitism (6%), the actual induced mortality of eggs may reach more than 15%. Parasitism of lepidopteran non-target species reached an average of 8% and thus, some degree of non-target parasitism after mass releases may be expected. To quantify the impact of the parasitoids in the orchards more precisely, naturally laid egg masses should be used in future trials to include host-finding cues of the host and host plants, and larger scale releases with potentially higher densities of parasitoids should be considered.
广食性卵寄生蜂（Geoffroy）（膜翅目：旋小蜂科）是欧洲入侵性害虫梨网蝽（Stål）（半翅目：网蝽科）最常见的卵寄生蜂。为了评估其对该害虫的防治效果，并在实际田间环境中验证对非靶标物种的潜在风险，连续三年在瑞士和意大利的四个果园进行了淹没式释放。总共释放了4300多头雌蜂，根据每个果园树木之间的距离，相当于每公顷释放11000至26000头雌蜂。采用当前释放策略对冷冻杀死的哨兵卵的寄生率平均为6%（范围：2%-16%），被认为不足以有效抑制该害虫。然而，其对梨网蝽卵死亡率的总体影响可能被低估了。如果将羽化前寄生蜂死亡率（3.3%）和寄主取食率（6%）加到观察到的寄生率（6%）上，梨网蝽卵的实际诱导死亡率可能超过15%。对鳞翅目非靶标物种的寄生率平均达到8%，因此，大规模释放后可能会出现一定程度的非靶标寄生现象。为了更精确地量化果园中寄生蜂的影响，未来试验应使用自然产下的卵块，以纳入寄主和寄主植物的寄主寻找线索，并应考虑进行更高密度的大规模释放。
