Psix saccharicola (Mani) and Trissolcus semistriatus (Nees) are the most abundant eggs parasitoids of the stink bug, Acrosternum arabicum Wagner, in pistachio orchards and have the potential to contribute to their suppression. However, treatment of orchards with broad-spectrum insecticides may greatly reduce populations of these beneficial natural enemies. Therefore, we conducted risk assessments and evaluated sublethal impacts of two insecticides routinely used in pistachio orchards: the organophosphate fenitrothion and a formulated mixture of the neonicotinoid thiamethoxam and the pyrethroid lambda-cyhalothrin on parasitism success, emergence and sex ratio of P. saccharicola and T. semistriatus. Based on the values of their risk quotients (RQ), which are derived from toxicity data, the two insecticide products would be classified as slightly-to-moderately toxic although an alternative metric, the safety factor (SF), showed them to be highly risky. Assessments of sublethal effects on adult wasps showed that insecticide exposure significantly reduced their ability to successfully parasitize stink bug eggs, and exposure of adult females reduced the emergence, survival, and proportion of females of their progeny, which could disrupt biological control for an extended period of time. Analysis of the decreased emergence and parasitism for P. saccharicola and T. semistriatus in accordance with the standards of the International Organization for Biological Control (IOBC) indicate that fenitrothion is slightly harmful to both parasitoid species whereas the mixture of thiamethoxam + lambda-cyhalothrin is moderately harmful. These findings will be useful for integrating insecticides and egg parasitoids into a comprehensive integrated pest management program for managing stink bugs populations in pistachio orchards.

中文翻译：

---

开心果生态系统中使用的选定杀虫剂对臭虫（半翅目：蝽科）的两种卵寄生蜂（膜翅目：鳞翅目）的毒性风险评估

Psix saccharicola (Mani) 和 Trissolcus semistriatus (Nees) 是开心果园中最丰富的臭虫 Acrosternum arabicum Wagner 的卵寄生蜂，并有可能有助于抑制它们。然而，用广谱杀虫剂处理果园可能会大大减少这些有益天敌的数量。因此，我们进行了风险评估并评估了开心果园中常用的两种杀虫剂的亚致死影响：有机磷杀虫剂和新烟碱类噻虫嗪和拟除虫菊酯 λ-三氯氟氰菊酯的配制混合物对 P. saccharicola 和 T. . 半纹状体。基于从毒性数据得出的风险商 (RQ) 值，这两种杀虫剂产品将被归类为轻度至中度毒性，尽管替代指标安全系数 (SF) 显示它们具有高风险。对成年黄蜂的亚致死影响的评估表明，杀虫剂暴露显着降低了它们成功寄生臭虫卵的能力，成年雌性的暴露降低了其后代雌性的出现、存活和比例，这可能会在很长一段时间内破坏生物控制的时间。根据国际生物防治组织 (IOBC) 的标准，对 P. saccharicola 和 T. semistriatus 的出苗率和寄生率降低的分析表明，杀螟硫磷对这两种寄生蜂物种都有轻微的危害，而噻虫嗪 + λ-三氯氟氰菊酯的混合物是中度有害。