Olfactory response of the ladybird beetle <Emphasis Type="Italic">Stethorus gilvifrons</Emphasis> to two preys and herbivore-induced plant volatiles

The spider mites Tetranychus urticae Koch and Panonychus ulmi (Koch) (Tetranychidae) cause severe economic losses to vegetable farms and deciduous fruit orchards in Turkey. One of their predators, the ladybird beetle Stethorus gilvifrons (Muls.) (Col., Coccinellidae), aggregates on mite-infested patches of plants. The present study assessed whether there is a role for herbivore-induced plant volatiles (HIPVs) and/or odors emitted directly from these two mite species in the aggregative response of ladybird beetles. The olfactory responses of the predator females to volatiles from T. urticae- and/or P. ulmi-infested sweet pepper (four cultivars, viz. ‘Demre’, ‘Yalova Carliston’, ‘Kandil Dolma’ and ‘Yag Biberi’), kidney bean (cv. ‘Barbunya’) and apple (M9 rootstock) were investigated using a two-choice olfactometer. Our results showed that HIPVs emitted from both T. urticae- and P. ulmi-infested plants significantly attracted S. gilvifrons adults for all plants except the sweet pepper cv. Yag Biberi. In addition, it was found that volatiles from apple plants infested by T. urticae and, especially, P. ulmi are more attractive for S. gilvifrons females than those emitted by other infested plants. The results also suggest that the odors of T. urticae adults and their products might influence the attraction of S. gilvifrons females.     

Population density and feeding duration of cabbage looper larvae on tomato plants alter the levels of plant volatile emissions

BACKGROUND: As part of their indirect defense, plants under herbivore attack release volatile chemicals that attract natural enemies of the herbivore. This is a very well-documented phenomenon. However, relatively few studies have investigated the response of plants to different population levels of herbivores and their feeding duration. RESULTS: Working with larvae of the cabbage looper, Trichoplusia ni (Hübner), and tomato plants, Lycopersicon esculentum Mill cv. clarence, and using an ultrafast gas chromatograph (the zNose™) for volatile analyses, the authors studied the effect of larval density and feeding duration on levels of plant volatile emissions. Intense herbivory caused higher emission levels of the herbivore-induced plant volatiles (HIPVs) (Z)-3-hexenyl acetate, (E)-β-ocimene and β-caryophyllene than those caused by moderate herbivory. When herbivory had ceased following 12–24 h of larval feeding, plants kept releasing HIPVs at a high level for a longer period of time than they did following only 6 h of larval feeding. The plants' slow adjustment in their volatile emissions following prolonged larval feeding might be strategic, as such feeding is more likely to have ceased just temporarily. CONCLUSION: This information may help in the development of a pest monitoring system that is based on herbivore-induced plant volatiles. Copyright © 2011 Society of Chemical Industry     

天敌植物支持系统及化学生态调控在粉虱防治中的应用

新型生物防治方法逐渐替代了预防性差、持效性短的传统生物防治,它包括以延长天敌寿命、延长控害时间为目的的天敌植物支持系统、利用信息化合物调控害虫、天敌的行为与传统生物防治相结合的防治方法等。笔者从植物支持系统和化学生态调控粉虱、天敌两个方面综述了粉虱的生物防治研究现状。在农业生态环境中,植食性昆虫和天敌均会遇到多种气味物质,这些也是粉虱和天敌进行食物定位、寄主或猎物定位所依赖的主要通讯工具。通过查阅近20年来粉虱及其天敌的化学生态学相关研究,整理对粉虱在寄主植物定位、天敌定位粉虱过程中具有调节作用的植物挥发性物质及利它素。期望能在农业生产上将化学信息物质与植物支持系统联合使用,调控粉虱和天敌的行为,减少害虫对作物的危害,延长天敌寿命,增强生物防治效果。     

植食性昆虫诱导的挥发物及其 在害虫防治中的作用

植物受到植食性昆虫为害后、会通过间接防御途径产生和释放一种挥发性气体（HIPVs）、HIPVs 对植食 性昆虫及其天敌具有重要的调控作用、对于害虫可以起到有效防治作用。HIPVs 的释放机制主要分为JA 和SA 两种 信号途径、不同植食性昆虫会诱导不同信号途径的激活。主要从种植抗虫栽培品系尧应用转基因植物尧人工释放合成 的HIPVs尧利用外源性化学物质等方面综述了利用HIPVs 进行生物防治的现状、可为进一步开发利用HIPVs 进行农 业防治提供一定理论基础。