寄生蜂基于嗅觉信号识别的宿主定位及其机制的研究进展

Research progress on host location of parasitoids based on olfactory signal recognition and its mechanism

寄生蜂对宿主的成功定位是其繁衍后代的关键步骤之一,主要受挥发性化合物的调节。首先,雌性寄生蜂可根据寄主植物挥发物尤其是植食性昆虫诱导的植物挥发物(herbivore-induced plant volatiles,HIPVs)对宿主的栖息环境进行远距离定位,它们可根据HIPVs提供的信号缩小宿主范围,而HIPVs的混合物极为复杂,其成分和含量受多种因素的调节。尽管如此,萜类是HIPVs中常见的化合物,且被多数行为研究证实在寄生蜂宿主定位中发挥作用。随后,当寄生蜂发现并降落到与宿主相关的植物后,它们可利用宿主衍生的信号近距离定位宿主。宿主的虫体、茧和粪便等释放的挥发性化合物对寄生蜂具有吸引作用,有些宿主粪便的气味可以作为寄生蜂执行宿主定位行为的主信号,而且宿主粪便挥发物的成分因昆虫取食的植物种类的不同而发生变化。此外,来自寄生蜂自身的信息化学物质也有助于同种寄生蜂的其他个体对宿主的定位。寄生蜂对气味分子的感知依赖其主要位于触角上的嗅觉感器,而关于其嗅觉识别的分子机制的研究仍较为薄弱。由于气味结合蛋白(odorant-binding proteins,OBPs)是嗅觉系统中介导气味识别的关键蛋白,所以大多数研究仅限集中于触角OBPs的分析。据现有研究报道,在不同种寄生蜂之间,编码OBPs的基因数量具有较大的差异,且多数研究通过基因沉默、荧光竞争结合检测、分子对接等技术手段证实了OBPs在寄生蜂的宿主定位中发挥着重要作用。寄生蜂宿主定位行为及其嗅觉机制的研究具有重要的生态学意义,同时在农业害虫的综合治理中具有很好的应用前景,在田间施用挥发性化合物或种植能够释放有用挥发物的伴生植物和转基因植物可以增强寄生蜂对宿主的定位,从而达到更好的害虫生物防控效果。

Successfully locating a host is one of the crucial steps in parasitoid reproduction,which is regulated mainly by volatile compounds.Firstly,female parasitoids often use volatiles from host plants,especially herbivore-induced plant volatiles(HIPVs),to locate the habitat of their hosts at long distances,which helps female parasitoids narrow their host searching range according to the cues provided by HIPVs.The blends of HIPVs are extremely complicated,and their components and contents can be modulated by a wide range of factors.Nevertheless,terpenoids are common compounds in HIPVs and have been confirmed by most behavioral studies to play a role in host localization of parasitoids.Subsequently,when the parasitoids find a plant related to hosts and land on them,they exploit host-derived cues at a close range to locate hosts.Parasitoids are usually attracted to volatile compounds released from the host body,cocoon,feces,etc.The odor of some host feces can be used as the main cues for parasitoids to locate hosts.Moreover,the components of volatiles in host feces may vary among plant species which insects feed.In addition,semiochemicals from the parasitoid itself are also beneficial for other individuals of the same species to locate their hosts.Sensory perception of odor molecules by parasitoids relies on olfactory sensilla,primarily located on the antennae,but the research on the molecular mechanism of their olfactory recognition is still limited.Because odorant-binding proteins(OBPs)are the crucial proteins in the olfactory system that mediate odor recognition,most studies only focus on the analysis of antennal OBPs.According to the current research,the number of genes encoding OBPs is highly variable among parasitiod species,and most studies have verified that OBPs play an important role in host location of parasitoids by means of gene silencing,fluorescence competitive binding assay,molecular docking and so on.Research on host localization and olfactory mechanism of parasitoids has important ecological significance,and also has a good application perspective in the integrated management of agricultural insect pests.Applying volatile compounds,or growing companion plants and transgenic plants that emit useful volatiles can enhance the host location of parasitoids in the field,so as to achieve a better biological control efficacy against insect pests.