Faccoli Massimo, Blazenec Miroslav, Schlyter Fredrik
Chemical Ecology, Department of Crop Sciences, Swedish University of Agricultural Sciences (SLU), P.O. Box 44, SE-230 53 Alnarp, Sweden.
J Chem Ecol. 2005 Apr;31(4):745-59. doi: 10.1007/s10886-005-3542-z.
Research on host selection by bark and wood boring insects has concentrated on flight orientation behavior. Less is known of the factors that govern the steps successive to host landing. Here, we discuss chemical factors involved in host acceptance by bark beetles and a new microassay. Adult males and females of Ips typographus were offered an artificial diet treated with various concentrations of different plant-derived compounds (host terpenes and nonhost compounds) in a no-choice mode. Beetles were tested individually in a glass tube for 4 hr, and the length of feeding was measured and compared to a control (diet with only solvent). The first effect was diet rejection, especially when nonhost compounds were tested at high concentrations. Most compounds reduced feeding, in proportion to concentration. Females fed more readily than males after addition of both host and nonhost compounds. Diet removal was significantly affected by all the tested factors (sex, compound, dose) as well as by their interactions. With increased concentrations, males were more responsive than females to antifeedants, as all compounds (except juglone) showed clear sex differences of diet consumption. 3-Octanol, 1-hexanol, and a Green Leaf Volatile (GLV)-blend (three C6 alcohols) showed the strongest antifeedant effects, which started at a low dose (0.1%) and had a low Effective Dose 50 (ED50, 0.3-1%). In contrast, host monoterpenes, limonene and alpha-pinene, inhibited feeding at high doses (10-30%) only, with ED50 > 10%. The highest Antifeedant Indexes were shown by verbenone, carvone, and 1-hexanol (AFI = 0.90-1.00). Both host and nonhost compounds inhibited feeding at some concentration. No significant stimulation of feeding by any host compound at concentrations reported in the literature as optimal were found, with the possible exception of alpha-pinene at low concentrations in females.
对蛀干害虫寄主选择的研究主要集中在飞行定向行为上。对于决定寄主着陆后续步骤的因素，人们了解较少。在此，我们讨论参与小蠹虫寄主接受过程的化学因素以及一种新的微量测定法。在无选择模式下，向云杉八齿小蠹的成年雌雄个体提供用不同浓度的不同植物源化合物（寄主萜类化合物和非寄主化合物）处理过的人工饲料。将甲虫单独置于玻璃管中4小时，测量取食时长并与对照组（仅含溶剂的饲料）进行比较。首先观察到的是对饲料的拒食现象，尤其是在测试高浓度非寄主化合物时。大多数化合物都会使取食减少，且与浓度成正比。添加寄主和非寄主化合物后，雌虫比雄虫更易取食。饲料消耗量受到所有测试因素（性别、化合物、剂量）及其相互作用的显著影响。随着浓度增加，雄虫比雌虫对拒食剂更敏感，因为所有化合物（除胡桃醌外）在饲料消耗量上均表现出明显的性别差异。3 - 辛醇、1 - 己醇和一种绿叶挥发物混合物（三种C6醇类）表现出最强的拒食作用，在低剂量（0.1%）时就开始起作用，且有效剂量50（ED50，0.3 - 1%）较低。相比之下，寄主单萜类化合物柠檬烯和α - 蒎烯仅在高剂量（10 - 30%）时抑制取食，其ED50 > 10%。最高的拒食指数由马鞭草烯酮、香芹酮和1 - 己醇呈现（拒食指数 = 0.90 - 1.00）。寄主和非寄主化合物在某些浓度下均会抑制取食。在文献报道的最佳浓度下，未发现任何寄主化合物对取食有显著刺激作用，雌性个体中低浓度的α - 蒎烯可能是个例外。
