Adoxophyes honmai, a serious pest of tea plants, prefers to lay eggs on mature tea leaves rather than young leaves. Here, we examined a hypothesis that Ascogaster reticulata, an egg-larval parasitoid of A. honmai, increases the likelihood of encountering host egg masses by searching mature tea leaves when host-derived cues are not available. In a dual-choice bioassay using a four-arm olfactometer, A. reticulata preferred odor from intact, mature leaves versus young leaves. Based on volatile analysis with gas chromatography-mass spectrometry (GC-MS), we identified 5 and 10 compounds from mature and young leaf volatiles, respectively. The 5 components in the extract from intact mature leaves included (Z)-3-hexenyl acetate, (E)-β-ocimene, linalool, (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), and methyl salicylate. When each individual compound, or quaternary and quintenary blends of them, ratios of which were adjusted to match those of mature leaf volatiles, were provided, parasitoids preferred the full mixture and the quaternary blend devoid of DMNT to the solvent control. Methyl salicylate, one of the components of preferred blends, was not detected among young leaf volatiles. We concluded that the volatile composition of tea leaves changes, depending on their maturity, and that this composition affects foraging behavior of the parasitoid, which is closely related to the host herbivore’s oviposition preference.

本草（Adoxophyes honmai）是一种严重的茶树害虫，它更喜欢在成熟的茶叶上产卵，而不是在嫩叶上产卵。在这里，我们检查了一个假说，即网纹拟南芥（A. honmai）的卵幼虫拟寄生虫，在没有宿主来源的线索时，通过搜索成熟的茶叶，增加了遇到宿主卵团块的可能性。在使用四臂嗅觉计的双重选择生物测定中，网状曲霉偏爱来自完整，成熟叶片的气味，而不是幼叶。基于气相色谱-质谱法（GC-MS）的挥发物分析，我们分别从成熟和年轻叶片挥发物中鉴定出5种和10种化合物。完整成熟叶片提取物中的5种成分包括在内（Z）-3-己烯基乙酸酯，（E）-β-内苯二酚，芳樟醇，（E）-4,8-​​二甲基-1,3,7-壬三烯（DMNT）和水杨酸甲酯。当提供每种单独的化合物，或它们的四元和五元混合物的比例，调整比例使其与成熟的叶挥发物相匹配时，拟寄生物优选完全混合物和不含DMNT的四元混合物作为溶剂控制剂。在幼叶挥发物中未检测到水杨酸甲酯，这是优选混合物的成分之一。我们得出的结论是，茶叶的挥发性成分会根据其成熟程度而变化，并且该成分会影响拟寄生虫的觅食行为，这与寄主草食动物的产卵偏好密切相关。