Exotic natural enemies that are imported to control a target pest may attack non-target species or disrupt the performance of other natural enemies of the target that are already present. We evaluate possible interactions between three parasitoid species, the native Telenomus nizwaensis and the imported Trichogramma brassicae and Trichogramma evanescens, when presented with Deudorix livia host eggs under high-density laboratory conditions. Deudorix livia is a butterfly which is an economically damaging pest in the Omani pomegranate agro-ecosystem. Most (73.5% overall) of the observed parasitism was by T. nizwaensis. It performed best when presented with host eggs in the absence of either of the Trichogramma species. These imported species thus have some potential to disrupt suppression of the pest by the indigenous natural enemy under lower-density conditions in the field, and neither of them achieved high parasitism rates themselves (laboratory conditions: T. brassicae = 12.5%; T. evanescens = 18.5%; with no evidence for any parasitism of field-collected eggs). Future efforts in this agro-ecosystem would best be directed towards encouraging T. nizwaensis, rather than towards importation of Trichogramma. Screening for negative effects of natural enemies on the pest suppression provided by other natural enemies is recommended.

为控制目标害虫而进口的外来天敌可能会攻击非目标物种或破坏已存在的目标其他天敌的表现。我们评估了三种寄生蜂物种（本地的 Telenomus nizwaensis 和进口的甘蓝赤眼蜂和伊氏赤眼蜂）在高密度实验室条件下与 Deudorix livia 宿主卵接触时可能存在的相互作用。 Deudorix livia 是一种蝴蝶，是阿曼石榴农业生态系统中具有经济破坏性的害虫。观察到的大多数（总共 73.5%）寄生是由 T. nizwaensis 寄生的。当在没有任何赤眼蜂物种的情况下提供宿主卵时，它表现最好。因此，在田间低密度条件下，这些进口物种有可能破坏本地天敌对害虫的抑制作用，而且它们本身都没有达到高寄生率（实验室条件：T. 甘蓝 = 12.5%；T. evanescens = 18.5%；没有任何现场收集的卵寄生的证据）。未来在这一农业生态系统中的努力最好是鼓励尼兹瓦红眼蜂，而不是进口赤眼蜂。建议筛选天敌对其他天敌抑制害虫的负面影响。