Erbilgin Nadir, Raffa Kenneth F
Department of Entomology, University of Wisconsin, 345 Russell Laboratories, Madison, WI, 53706, USA.
Oecologia. 2001 May;127(3):444-453. doi: 10.1007/s004420000606. Epub 2001 May 1.
Predators and parasitoids are known to exploit both plant volatiles and herbivore pheromones to locate their insect prey. However, the interaction of these chemical cues in prey location, and the implications of multiple sources of chemical cues to predator feeding breadth and tracking of herbivore counter adaptations, are less well understood. We evaluated the responses of three coleopteran predators to the pheromones and plant signals associated with two species of common bark beetle prey. Thanasimus dubius, Platysoma cylindrica, and Corticeus parallelus feed exclusively on the fauna within trees colonized by bark beetles. The predominant bark beetles in conifer forests of central Wisconsin are Ips pini and Ips grandicollis. The aggregation pheromone of Wisconsin I. pini contains ipsdienol, which occurs as (+) and (-) enantiomers, and lanierone, and the pheromone of I. grandicollis contains ipsenol. The major hosts of these bark beetles are Pinus resinosa, Pinus banksiana, and Pinus strobus, which contain monoterpenes as their predominant phytochemical volatiles. Monoterpenes by themselves did not attract predators. However, some monoterpenes significantly affected predator attraction to aggregation pheromones. Myrcene, and to a lesser extent 3-carene, reduced predator attraction. By contrast, α-pinene consistently enhanced attraction by all three predators to the pheromones of their Ips prey. However, the predators' responses were modulated by the stereochemistry of α-pinene, and these responses differed when confronted with the different pheromones of the two prey species. (+)-α-Pinene synergized predator responses to the pheromone of I. pini, whereas (-)-α-pinene synergized responses to the pheromone of I. grandicollis. This pattern occurred for all three predator species. Interactions between herbivore pheromones and host plant compounds may provide an important source of behavioral plasticity in predators, and facilitate their ability to track several cryptic species that are distributed across multiple plant species and that show semiochemical variation in space and time.
已知捕食者和寄生性天敌会利用植物挥发物和植食性昆虫信息素来定位它们的昆虫猎物。然而，这些化学信号在猎物定位中的相互作用，以及多种化学信号源对捕食者取食范围和追踪植食性昆虫反适应的影响，目前还不太清楚。我们评估了三种鞘翅目捕食者对与两种常见树皮甲虫猎物相关的信息素和植物信号的反应。黑角郭公虫、圆柱形扁郭公虫和平行扁郭公虫仅以被树皮甲虫侵害的树木中的动物为食。威斯康星州中部针叶林中主要的树皮甲虫是松果梢小蠹和大齿梢小蠹。威斯康星州松果梢小蠹的聚集信息素含有 ipsdienol（以(+)和(-)对映体形式存在）和拉尼尔酮，大齿梢小蠹的信息素含有 ipsenol。这些树皮甲虫的主要寄主是北美脂松、班克松和北美乔松，它们含有单萜作为主要的植物化学挥发物。单萜本身不会吸引捕食者。然而，一些单萜显著影响捕食者对聚集信息素的吸引力。月桂烯，以及程度较轻的 3 - 蒈烯，会降低捕食者的吸引力。相比之下，α - 蒎烯始终增强了所有三种捕食者对其松果梢小蠹猎物信息素的吸引力。然而，捕食者的反应受到α - 蒎烯立体化学的调节，并且当面对两种猎物物种的不同信息素时，这些反应有所不同。(+)-α - 蒎烯增强了捕食者对松果梢小蠹信息素的反应，而(-)-α - 蒎烯增强了对大齿梢小蠹信息素的反应。所有三种捕食者物种都出现了这种模式。植食性昆虫信息素与寄主植物化合物之间的相互作用可能为捕食者提供行为可塑性的重要来源，并促进它们追踪分布在多种植物物种上且在空间和时间上表现出化学信号变化的几种隐匿物种的能力。
