Fürstenau Benjamin, Hilker Monika
Dahlem Centre of Plant Sciences, Institute of Biology, Applied Zoology/Animal Ecology, Freie Universität Berlin, Haderslebener Str. 9, 12163, Berlin, Germany.
Julius Kühn-Institut, Federal Research Centre for Cultivated plants, Institute for Ecological Chemistry, Plant Analysis and Stored Product Protection, Königin-Luise-Str. 19, 14195, Berlin, Germany.
J Chem Ecol. 2017 Sep;43(9):858-868. doi: 10.1007/s10886-017-0885-1. Epub 2017 Sep 11.
Parasitic wasps which attack insects infesting processed stored food need to locate their hosts hidden inside these products. Their host search is well-known to be guided by host kairomones, perceived via olfaction or contact. Among contact kairomones, host cuticular hydrocarbons (CHCs) may provide reliable information for a parasitoid. However, the chemistry of CHC profiles of hosts living in processed stored food products is largely unknown. Here we showed that the ectoparasitoid Holepyris sylvanidis uses CHCs of its host Tribolium confusum, a worldwide stored product pest, as kairomones for host location and recognition at short range. Chemical analysis of T. confusum larval extracts by gas chromatography coupled with mass spectrometry revealed a rich blend of long-chain (C25-C30) hydrocarbons, including n-alkanes, mono-, and dimethylalkanes. We further studied whether host larvae leave sufficient CHCs on a substrate where they walk along, thus allowing parasitoids to perceive a CHC trail and follow it to their host larvae. We detected 18 CHCs on a substrate that had been exposed to host larvae. These compounds were also found in crude extracts of host larvae and made up about a fifth of the CHC amount extracted. Behavioral assays showed that trails of host CHCs were followed by the parasitoids and reduced their searching time until successful host recognition. Host CHC trails deposited on different substrates were persistent for about a day. Hence, the parasitoid H. sylvanidis exploits CHCs of T. confusum larvae for host finding by following host CHC trails and for host recognition by direct contact with host larvae.
寄生蜂会攻击侵染加工后储存食物的昆虫，它们需要找到隐藏在这些产品中的宿主。众所周知，它们的宿主搜索行为是由通过嗅觉或接触感知到的宿主利它素引导的。在接触利它素中，宿主表皮碳氢化合物（CHCs）可能为寄生蜂提供可靠信息。然而，生活在加工后储存食品中的宿主的CHC谱的化学组成在很大程度上尚不清楚。在这里，我们表明外寄生蜂Holepyris sylvanidis利用其宿主杂拟谷盗（一种世界性的仓储害虫）的CHCs作为利它素，用于在近距离定位和识别宿主。通过气相色谱-质谱联用对杂拟谷盗幼虫提取物进行化学分析，发现了丰富的长链（C25-C30）碳氢化合物混合物，包括正构烷烃、单甲基和二甲基烷烃。我们进一步研究了宿主幼虫是否会在它们走过的基质上留下足够的CHCs，从而使寄生蜂能够感知到CHC踪迹并追踪到宿主幼虫。我们在暴露于宿主幼虫的基质上检测到了18种CHCs。这些化合物也存在于宿主幼虫的粗提物中，约占提取的CHC总量的五分之一。行为试验表明，寄生蜂会追踪宿主CHC踪迹，并减少其搜索时间，直到成功识别宿主。沉积在不同基质上的宿主CHC踪迹可持续约一天。因此，寄生蜂H. sylvanidis通过追踪宿主CHC踪迹利用杂拟谷盗幼虫的CHCs来寻找宿主，并通过与宿主幼虫直接接触来识别宿主。
