Brodbeck Brent V, Mizell Russell F, French William J, Andersen Peter C, Aldrich James H
AREC-Monticello, University of Florida, Rt. 4 Box 4092, 32344, Monticello, FL, USA.
Oecologia. 1990 Jun;83(3):338-345. doi: 10.1007/BF00317557.
Homalodisca coagulata is a highly polyphagous xylem feeder with distinct seasonal patterns in it's selection of host plants. These patterns were examined in relation to the amino acid content of the xylem for four common host species; Lagerstroemia indica, Baccharis halimifolia, Prunus persica, and Prunus salicina. Xylem fluid was collected from each host species at times when numbers of feeding leafhoppers were both low and high. In each case, concentrations of amino acids were greatest when numbers were high. Similarly, comparisons between host species at given times showed that concentrations of amino acids were positively correlated with host selection. In a second study, amino acids of xylem were manipulated by budding scions of a non-preferred host (P. persica) on rootstocks of preferred (P. salinica) and non-preferred (P. persica) hosts. Morphology and phenology of the budded trees were similar to that of the scion species yet the xylem composition of amino acids was primarily dependent on the rootstock. Concentrations of amino acids and the preference of leafhoppers were roughly two-fold greater for scions of the preferred than the non-preferred rootstock. In both studies, amides (glutamine plus asparagine) were the amino acids most highly correlated with host selection. These compounds are the predominant amino acids in xylem fluid, have high nitrogen to carbon ratios, and account for a high percentage of the caloric value in xylem fluid. Many of the less abundant amino acids were positively correlated with host preference, but the correlations were less consistent and correlation coefficients were generally lower.
葡萄叶蝉是一种多食性木质部取食者，在寄主植物选择上具有明显的季节性模式。针对四种常见寄主植物（紫薇、卤地菊、桃和李），研究了这些模式与木质部氨基酸含量的关系。在取食叶蝉数量低和高的时期，从每种寄主植物收集木质部汁液。在每种情况下，叶蝉数量多的时候氨基酸浓度最高。同样，在特定时间对寄主植物进行比较表明，氨基酸浓度与寄主选择呈正相关。在第二项研究中，通过将非偏好寄主（桃）的接穗嫁接到偏好寄主（李）和非偏好寄主（桃）的砧木上，来操控木质部的氨基酸。嫁接树的形态和物候与接穗品种相似，但木质部氨基酸组成主要取决于砧木。对于偏好砧木的接穗，氨基酸浓度和叶蝉的偏好大约是非偏好砧木接穗的两倍。在两项研究中，酰胺（谷氨酰胺加天冬酰胺）是与寄主选择相关性最高的氨基酸。这些化合物是木质部汁液中的主要氨基酸，氮碳比高，在木质部汁液的热量值中占很高比例。许多含量较少的氨基酸与寄主偏好呈正相关，但相关性不太一致，相关系数通常较低。
