Department of Entomology, University of California, Riverside, CA 92521, USA.
J Chem Ecol. 2011 May;37(5):430-42. doi: 10.1007/s10886-011-9944-1. Epub 2011 Apr 12.
Natural enemies of herbivorous insects utilize numerous cues to locate and identify their prey. One class of such cues is volatile organic compounds (VOCs) often produced by plants after attack by herbivores (hereafter herbivore-induced plant volatiles or HIPVs). Under simplified laboratory conditions, natural enemies often make clear choices between different HIPV blends, but such clear choices may be more difficult in more complex field environments. We studied the impact of VOC production by the undomesticated species, Datura wrightii on predation of eggs and larvae of Lema daturaphila by the omnivore, Geocoris pallens in the field. HIPV production in D. wrightii is developmentally and seasonally constrained to the early stages of plant growth even though L. daturaphila and G. pallens inhabit plants throughout the plant's growing season. We, therefore, asked if predation of L. daturaphila by G. pallens might be similarly constrained seasonally. Higher levels of VOC production were associated with higher levels of predation throughout the growing season, and the greater quantities of VOC production in May caused greater increases in predation than did VOC production later in the season (June-September). However, predation in the absence of VOC production ranged from 60-70% in June-September compared to only 14% in May, probably because plants were already colonized by predators later in the season. High levels of VOCs in response to herbivore damage by D. wrightii therefore may aid in the discovery of herbivore-damaged plants early in the season but the seasonal decline in VOC production does not limit predation of L. daturaphila by G. pallens later in the season.
植食性昆虫的天敌利用许多线索来定位和识别它们的猎物。其中一类线索是挥发性有机化合物（VOCs），这些化合物通常是在食草动物（以下简称植食性诱导植物挥发物或 HIPV）攻击植物后产生的。在简化的实验室条件下，天敌通常会在不同的 HIPV 混合物之间做出明确的选择，但在更复杂的野外环境中，这种明确的选择可能更加困难。我们研究了非驯化物种曼陀罗（Datura wrightii）对杂食性昆虫芫菁（Geocoris pallens）捕食其幼虫和卵的影响，这种影响受到 VOC 产生的影响。尽管芫菁和芫菁栖息在植物的整个生长季节，但 D. wrightii 的 HIPV 产生在发育和季节上受到限制，只能在植物生长的早期阶段产生。因此，我们想知道芫菁对 L. daturaphila 的捕食是否也会受到季节的限制。在整个生长季节，较高水平的 VOC 产生与较高水平的捕食相关，而 5 月份更高水平的 VOC 产生导致捕食增加的幅度大于该季节后期（6 月至 9 月）的 VOC 产生。然而，在没有 VOC 产生的情况下，6 月至 9 月的捕食率在 60-70%之间，而 5 月的捕食率仅为 14%，这可能是因为植物在该季节后期已经被捕食者占据。因此，D. wrightii 受到草食性动物的损害后，大量产生 VOC 可能有助于在季节早期发现受损植物，但 VOC 产生的季节性下降不会限制 G. pallens 对 L. daturaphila 的捕食。
