1. The Western conifer seed bug Leptoglossus occidentalis, a native insect of North America, was accidentally introduced in Europe in the late 1990s. Since then, it has spread rapidly. Biological control could provide an efficient management option but natural enemies of the pest have been poorly examined in Europe.
2. In this study, we exposed sentinel egg masses and collected naturally laid egg masses in southern France in 2016 and 2017, to identify the egg parasitoids of L. occidentalis and investigate their potentials.
3. Three egg parasitoids were detected: Anastatus bifasciatus, Ooencyrtus pityocampae and Ooencyrtus telenomicida. The overall parasitism was low compared to that observed in the native range with 6.4% of all eggs being parasitized, while 17.1% of egg masses carried at least one parasitized egg. The total number of parasitized egg masses was similar between parasitoid species, but the mean number of parasitized eggs per egg mass was highest for A. bifasciatus (5.57 vs. 1.25 for Ooencyrtus spp.).
4. Sentinel egg masses underestimated the parasitism compared to natural egg masses (respectively, 1.42% and 7.71%).
5. Our results suggested that the three generalist parasitoids detected can respond in a Leptoglossus egg density-dependent manner, but this requires further investigations.

中文翻译：

---

原生卵寄生物对侵入性种虫 Leptoglossus occidentalis 的反应

1. 西方针叶树种虫Leptoglossus occidentalis是北美的一种本地昆虫，于 1990 年代后期意外引入欧洲。从那以后，它迅速传播。生物控制可以提供一种有效的管理选择，但在欧洲对这种害虫的天敌进行的检查很差。
2. 在这项研究中，我们于 2016 年和 2017 年在法国南部暴露了哨兵卵块并收集了自然产卵块，以鉴定L. occidentalis的卵寄生物并研究它们的潜力。
3. 中检测到卵寄生：平腹小天牛，Ooencyrtus pityocampae和Ooencyrtus telenomicida。与在本地范围内观察到的相比，总体寄生率较低，所有卵中有 6.4% 被寄生，而 17.1% 的卵块携带至少一个寄生卵。寄生卵块的总数为寄生物种之间的相似，但每个卵块寄生卵的平均数最高的是A.天牛（5.57与1.25 Ooencyrtus属）。
4. 与天然卵块相比，哨兵卵块低估了寄生性（分别为 1.42% 和 7.71%）。
5. 我们的结果表明，检测到的三种通才寄生蜂可以以Leptoglossus卵密度依赖性方式做出反应，但这需要进一步调查。