Cuticular hydrocarbons (CHCs) of host insects are used by many parasitic wasps as contact kairomones for host location and recognition. As the chemical composition of CHCs varies from species to species, the CHC pattern represents a reliable indicator for parasitoids to discriminate host from non-host species. Holepyris sylvanidis is an ectoparasitoid of beetle larvae infesting stored products. Previous studies demonstrated that the larval CHC profile of the confused flour beetle, Tribolium confusum, comprises long chain linear and methyl-branched alkanes (methyl alkanes), which elicit trail following and host recognition in H. sylvanidis. Here we addressed the question, whether different behavioral responses of this parasitoid species to larvae of other beetle species are due to differences in the larval CHC pattern. Our study revealed that H. sylvanidis recognizes and accepts larvae of T. confusum, T. castaneum and T. destructor as hosts, whereas larvae of Oryzaephilus surinamensis were rejected. However, the latter species became attractive after applying a sample of T. confusum larval CHCs to solvent extracted larvae. Chemical analyses of the larval extracts revealed that CHC profiles of the Tribolium species were similar in their composition, while that of O. surinamensis differed qualitatively and quantitatively, i.e. methyl alkanes were present as minor components on the cuticle of all Tribolium larvae, but were absent in the O. surinamensis CHC profile. Furthermore, the parasitoid successfully recognized solvent extracted T. confusum larvae as hosts after they had been treated with a fraction of methyl alkanes. Our results show that methyl alkanes are needed for host recognition by H. sylvanidis.

寄主昆虫的表皮碳氢化合物（CHC）被许多寄生性黄蜂用作接触海洛酮，用于寄主的定位和识别。由于CHC的化学组成因物种而异，因此CHC模式代表了寄生物区分宿主与非宿主物种的可靠指标。幽门螺杆菌是甲虫幼虫侵染贮藏产品的外寄生虫。以前的研究表明，混淆的甲虫Tribolium confusum的幼虫CHC谱包含长链线性和甲基支链烷烃（甲基烷烃），这些化合物会引起追尾和宿主识别。。在这里，我们解决了这个问题：这种寄生虫物种对其他甲虫的幼虫的不同行为反应是否是由于幼虫CHC模式的差异引起的。我们的研究表明，H. sylvanidis识别和接受的幼虫T. confusum，赤拟谷盗和T.析构函数作为主机，而幼虫锯谷盗被拒绝。但是，在将T. confusum幼虫CHC样品应用于溶剂提取的幼虫后，后一种变得有吸引力。幼虫提取物的化学分析表明，Tribolium物种的CHC组成相似，而苏里南O.定性和定量上存在差异，即甲基链烷作为所有Tribolium幼虫的表皮中的次要成分存在，但在O. surinamensis CHC谱中不存在。此外，该寄生虫在用一部分甲基烷烃处理后，成功地将溶剂提取的浓密锥虫幼虫成功识别为宿主。我们的结果表明，甲基烷烃是鉴定H. sylvanidis所需的。