Newbery D McC, Hill M G, Waterman P G
Department of Biological Science, Stirling University, FK9 4LA, Stirling, Scotland.
Entomology Division, D.S.I.R., Private Bag, Auckland, New Zealand.
Oecologia. 1983 Dec;60(3):333-339. doi: 10.1007/BF00376848.
The relative susceptibility of thirty-tree species to feeding by the coccid, Icerya seychellarum, (from a previous atoll survey) were correlated with four morphological characters (leaf lamina and midrib thicknesses, density of hairs on leaf underside and presence of waxy upper leaf surface) and the concentrations of six mineral elements (N, P, K, Ca, Mg and Na) and three measures of chemical defense (total phenols, condensed tannins and alkaloids). For twenty-two species four phenological variables, from a separate two year study, were also correlated with susceptibility.Lamina thickness, presence of dense hairs and the concentrations of alkaloids or condensed tannins were significantly correlated with host susceptibility. The ideal host has thick, evergreen and hairless leaves. Some host species with high concentrations of secondary chemicals were also highly susceptible and a new hypothesis suggests that stylet manoeuvrability enables a coccid to avoid these substances in thick, but not thin, leaves.Experimental 'seeding' of crawlers on to eleven host species showed marked differences in susceptibility in different stages of the life-cycle: presence of dense hairs appeared to deter settlement whilst thick lamina enhanced coccid survival.
（根据之前环礁调查）33种树木对塞舌尔绵蚧取食的相对易感性，与四个形态特征（叶片和中脉厚度、叶背面毛的密度以及叶片上表面蜡质的有无）、六种矿质元素（氮、磷、钾、钙、镁和钠）的浓度以及三种化学防御指标（总酚、缩合单宁和生物碱）相关。对于22种树木，来自另一项为期两年研究的四个物候变量也与易感性相关。叶片厚度、浓密毛的存在以及生物碱或缩合单宁的浓度与寄主易感性显著相关。理想的寄主具有厚的、常绿且无毛的叶子。一些次生化学物质浓度高的寄主物种也高度易感，一个新的假说是，口针的可操作性使蚧虫能够在厚叶而非薄叶中避开这些物质。在11种寄主物种上对若虫进行实验性“接种”，结果表明在生命周期的不同阶段易感性存在显著差异：浓密毛的存在似乎会阻止若虫定居，而厚叶片则会提高蚧虫的存活率。
