Cha Dong H, Powell Thomas H Q, Feder Jeffrey L, Linn Charles E
Department of Entomology, NYS Agricultural Experiment Station, Cornell University, Geneva, NY, 14456, USA.
US Pacific Basin Agricultural Research Center, USDA-ARS, Hilo, HI, 96720, USA.
J Chem Ecol. 2018 Aug;44(7-8):671-680. doi: 10.1007/s10886-018-0977-6. Epub 2018 Jun 20.
A new blend of volatiles was identified for the fruit of downy red hawthorn, Crataegus mollis, that is attractive to Rhagoletis pomonella flies infesting this host in the northeastern USA. The new blend was as attractive as the previously identified mixture but is more complex in the number of odorants (six in the old versus ten in the new) and differs significantly in the ratio of three volatiles, 3-methylbutan-1-ol, butyl hexanoate, and dihydro-β-ionone, that are common to both blends and exerted agonist or antagonist effects on behavior in a flight tunnel assay. However, behavioral results with the old and new northern hawthorn blends, as well as modified blends with substituted ratios of 3-methylbutan-1-ol, butyl hexanoate, dihydro-β-ionone, indicated that the 'agonist' or 'antagonist' effects of these volatiles depended on the ratio, or balance of compounds within the blend. In addition, the new blend contains a number of esters identified from the headspace of domesticated apple, Malus domestica, that are attractive to apple-origin R. pomonella, and present in the five other blends from southern hawthorns, including the southern C. mollis var. texana blend, but are not part of the previously identified blend from northern C. mollis fruit. This finding supports the hypothesis that in addition to providing specificity to the odor blends of the northern and southern hawthorn populations, the presence of the significant amounts of ester compounds in the new northern hawthorn blend might have provided a source of standing variation that could help explain the shift in host preference by C. mollis-infesting flies to introduced apple in the mid-1800's.
已鉴定出一种新的挥发性混合物，存在于柔毛山楂（Crataegus mollis）果实中，对美国东北部侵害该寄主的苹果实蝇（Rhagoletis pomonella）具有吸引力。这种新混合物与之前鉴定出的混合物一样具有吸引力，但气味成分数量更多（旧混合物中有六种，新混合物中有十种），并且在三种挥发性物质（3-甲基丁醇、己酸丁酯和二氢-β-紫罗兰酮）的比例上有显著差异，这三种挥发性物质在两种混合物中都有，且在飞行隧道试验中对行为产生激动或拮抗作用。然而，使用旧的和新的北方山楂混合物以及含有替代比例的3-甲基丁醇、己酸丁酯、二氢-β-紫罗兰酮的改良混合物进行的行为学结果表明，这些挥发性物质的“激动”或“拮抗”作用取决于混合物中化合物的比例或平衡。此外，新混合物包含一些从驯化苹果（Malus domestica）顶空鉴定出的酯类物质，这些酯类物质对苹果来源的苹果实蝇具有吸引力，并且存在于来自南方山楂的其他五种混合物中，包括南方的柔毛山楂变种德克萨斯山楂（C. mollis var. texana）混合物，但不是之前从北方柔毛山楂果实中鉴定出的混合物的一部分。这一发现支持了这样一种假设，即新的北方山楂混合物中除了为北方和南方山楂种群的气味混合物提供特异性外，大量酯类化合物的存在可能提供了一种持续变异的来源，这有助于解释在19世纪中叶侵害柔毛山楂的实蝇向引入的苹果转变寄主偏好的现象。
