Whether increased natural enemy density or adding a second natural enemy species will provide superior pest suppression in greenhouse augmentative biological control is unknown for many commercially available natural enemy species. In this study, we use sweetpotato whiteflies, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), on poinsettias, Euphorbia pulcherrima Willd. ex Klotzsch (Malpighiales: Euphorbiaceae), to determine whether adding Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae) to Eretmocerus eremicus Rose and Zolnerowich (Hymenoptera: Aphelinidae) is better for B. tabaci suppression compared with either natural enemy alone, both with and without challenges with whitefly immigration or delayed natural enemy releases. The number of whiteflies on caged poinsettias treated with different natural enemy release rates (single or double rate), natural enemy species (one or two species), natural enemy delayed release (weeks 4 and 8), and whitefly immigration treatments (introduced at week 4 or week 8) was censused biweekly for 16 wk. Both species used in combination provided similar or better suppression of whiteflies compared with either natural enemy alone. Both species combined also provided superior suppression of whiteflies when challenged with whitefly immigration or delays in natural enemy releases compared with E. eremicus alone. Whitefly immigration or delays in E. eremicus releases did not increase whitefly populations, suggesting that suppression of whiteflies by E. eremicus alone is relatively robust. This study found no evidence for negative interactions between E. eremicus and A. swirskii for suppressing B. tabaci.

中文翻译：

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在增强生物控制中添加天敌以应对害虫移民和延迟天敌释放

对于许多商业上可获得的天敌物种来说，增加的天敌密度或添加第二个天敌物种是否会在温室增强生物控制中提供卓越的害虫抑制作用是未知的。在这项研究中，我们使用红薯粉虱，烟粉虱（Gennadius）（半翅目：粉虱科），在一品红，大戟属 pulcherrima Willd。ex Klotzsch (Malpighiales: Euphorbiaceae)，以确定将 Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae) 添加到 Eretmocerus eremicus Rose 和 Zolnerowich (Hymenoptera: Aphelinidae) 是否比单独的天敌更好地抑制烟粉虱，两者有和没有粉虱移民或延迟天敌释放的挑战。不同天敌释放率（单倍率或双倍率）、天敌物种（一种或两种）、天敌延迟释放（第 4 周和第 8 周）和粉虱移民处理（每周引入）处理的笼养一品红上粉虱的数量4 或第 8 周）每两周进行一次普查，为期 16 周。与单独使用任何一种天敌相比，两种组合使用的物种对粉虱的抑制作用相似或更好。与单独的 E. eremicus 相比，当受到粉虱移民或天敌释放延迟的挑战时，这两种物种的结合还可以更好地抑制粉虱。粉虱移民或 E. eremicus 释放的延迟并没有增加粉虱的数量，这表明仅 E. eremicus 对粉虱的抑制相对稳健。