Data from: Intraspecific variation in herbivore-induced plant volatiles influences the spatial range of plant-parasitoid interactions

Chemical information influences the behaviour of many animals, thus affecting species interactions. Many animals forage for resources that are heterogeneously distributed in space and time, and have evolved foraging behaviour that utilizes information related to these resources. Herbivore-induced plant volatiles (HIPVs), emitted by plants upon herbivore attack, provide information on herbivory to various animal species, including parasitoids. Little is known about the spatial scale at which plants attract parasitoids via HIPVs under field conditions and how intraspecific variation in HIPV emission affects this spatial scale. Here, we investigated the spatial scale of parasitoid attraction to two cabbage accessions that differ in relative preference of the parasitoid Cotesia glomerata when plants were damaged by Pieris brassicae caterpillars. Parasitoids were released in a field experiment with plants at distances of up to 60 m from the release site using intervals between plants of 10 or 20 m to assess parasitism rates over time and distance. Additionally, we observed host-location behaviour of parasitoids in detail in a semi-field tent experiment with plant spacing up to 8 m. Plant accession strongly affected successful host location in field set-ups with 10 or 20 m intervals between plants. In the semi-field set-up, plant finding success by parasitoids decreased with increasing plant spacing, differed between plant accessions, and was higher for host-infested plants than for uninfested plants. We demonstrate that parasitoids can be attracted to herbivore-infested plants over large distances (10m or 20m) in the field, and that stronger plant attractiveness via HIPVs increases this distance (up to at least 20m). Our study indicates that variation in plant traits can affect attraction distance, movement patterns of parasitoids, and ultimately spatial patterns of plant-insect interactions. It is therefore important to consider plant-trait variation in HIPVs when studying animal foraging behaviour and multi-trophic interactions in a spatial context.化学信息可调控诸多动物的行为，进而影响物种间的相互作用。诸多动物会搜寻在时空上呈异质性分布的资源，并演化出利用这类资源相关信息的觅食行为。植食性昆虫诱导的植物挥发物（Herbivore-induced plant volatiles, HIPVs）是植物遭受植食性昆虫攻击时释放的信号物质，可向包括寄生蜂在内的多种动物传递植食危害相关信息。目前学界对野外条件下植物通过HIPVs吸引寄生蜂的空间尺度，以及HIPVs释放的种内变异如何影响该空间尺度的认知仍较为匮乏。本研究以两个甘蓝品系为对象，二者在被大菜粉蝶（Pieris brassicae）幼虫取食后，对寄生蜂菜蛾盘绒茧蜂（Cotesia glomerata）的相对吸引偏好存在显著差异，借此探究相关科学问题。我们设置野外试验：将寄生蜂释放于距离释放点最远60米的区域，植物布设间距设为10米或20米，以此评估不同时间与距离下的寄生率。此外，我们还在植物间距最高达8米的半田间笼养试验中，详细观测了寄生蜂的寄主定位行为。在植物间距为10米或20米的野外布设方案中，甘蓝品系对寄生蜂成功定位寄主的行为具有显著影响。在半田间试验中，寄生蜂找到植物的成功率随植物间距增大而降低，且不同甘蓝品系间存在显著差异；同时，被寄主取食的植株的吸引成功率显著高于未被取食的植株。本研究证实，野外条件下寄生蜂可在较远的距离（10米或20米）范围内被植食性昆虫取食的植株所吸引，且通过HIPVs实现的更强植物吸引效应可拓展该吸引距离（至少可达20米）。本研究表明，植物性状的变异可影响寄生蜂的吸引距离与移动模式，最终改变植物-昆虫相互作用的空间格局。因此，在空间尺度下探究动物觅食行为与多营养级相互作用时，需纳入HIPVs相关的植物性状变异这一关键因素。