International Centre of Insect Physiology and Ecology (icipe), Plant Health Department, P.O. Box 30772-00100, Nairobi, Kenya.
Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa.
J Chem Ecol. 2021 Feb;47(2):192-203. doi: 10.1007/s10886-021-01245-2. Epub 2021 Jan 16.
Natural enemies locate their herbivorous host and prey through kairomones emitted by host plants and herbivores. These kairomones could be exploited to attract and retain natural enemies in crop fields for insect pest control. The parasitoid Encarsia formosa preferentially parasitises its whitefly host, Trialeurodes vaporariorum, a major pest of tomato Solanum lycopersicum, thus offering an effective way to improve whitefly control. However, little is known about the chemical interactions that occur in E. formosa-T. vaporariorum-S. lycopersicum tritrophic system. Using behavioural assays and chemical analyses, we investigated the kairomones mediating attraction of the parasitoid to host-infested tomato plants. In Y-tube olfactometer bioassays, unlike volatiles of healthy tomato plants, those of T. vaporariorum-infested tomato plants attracted E. formosa, and this response varied with host infestation density. Coupled gas chromatography/mass spectrometric analyses revealed that host infestation densities induced varying qualitative and quantitative differences in volatile compositions between healthy and T. vaporariorum adult-infested tomato plants. Bioassays using synthetic chemicals revealed the attractiveness of 3-carene, β-ocimene, β-myrcene and α-phellandrene to the parasitoid, and the blend of the four compounds elicited the greatest attraction. Our results suggest that these terpenes could be used as an attractant lure to recruit the parasitoid E. formosa for the control of whiteflies in tomato crop fields.
天敌通过宿主植物和植食动物释放的信息素来定位其植食性宿主和猎物。这些信息素可被利用来吸引并保留作物田中的天敌，以控制昆虫害虫。寄生蜂Encarsia formosa 优先寄生其粉虱宿主 Trialeurodes vaporariorum，而 Trialeurodes vaporariorum 是番茄 Solanum lycopersicum 的主要害虫，因此为改善粉虱控制提供了一种有效方法。然而，关于在 E. formosa-T. vaporariorum-S. lycopersicum 三营养级系统中发生的化学相互作用知之甚少。通过行为测定和化学分析，我们研究了介导寄生蜂对受粉虱侵害的番茄植物吸引力的信息素。在 Y 型管嗅觉计生物测定中，与健康番茄植物的挥发物不同，受 T. vaporariorum 侵害的番茄植物的挥发物吸引了 E. formosa，而这种反应随宿主侵害密度而异。气相色谱/质谱联用分析表明，宿主侵害密度诱导健康和 T. vaporariorum 成虫侵害的番茄植物之间的挥发物组成发生了不同的定性和定量差异。使用合成化学物质进行的生物测定表明，3-蒈烯、β-罗勒烯、β-月桂烯和α-苎烯对寄生蜂具有吸引力，而这四种化合物的混合物则引起了最大的吸引力。我们的结果表明，这些萜烯类化合物可用作引诱剂，诱捕寄生蜂 E. formosa，以控制番茄作物田中的粉虱。
