Ghebremariam Tsedal T, Krüger Kerstin, Reinhardt Carl F, Robbertse Petrus J
Department of Zoology & Entomology, University of Pretoria, Private Bag X20, Pretoria, 0028, South Africa.
Environ Entomol. 2014 Oct;43(5):1286-94. doi: 10.1603/EN14007.
Plant morphological changes mediated by growth conditions are linked to changes in host preference of herbivores. Understanding how these morphological changes influence herbivore feeding is critical in the interpretation of results of host evaluation of candidate weed biocontrol agents in quarantine and improvement of the evaluation system. We determined the effect of plant growth conditions on leaf trichomes and host choice of Conchyloctenia hybrida Boheman, an insect adapted to the removal of trichomes before feeding. The study included four Solanum species: Solanum lichtensteinii Willdenow (natural host of C. hybrida), Solanum mauritianum Scopoli, Solanum melongena L., and Solanum tuberosum L.. Plants were grown in either full sun, shade, a glasshouse, or in a growth-chamber. Plants grown in full sun had a higher leaf trichome density than those in shade or controlled environments. S. mauritianum had the highest trichome density and thickness of trichome layer. In a multiple-choice test using excised leaves, feeding by C. hybrida was higher on Solanum plants grown in the controlled environment as compared with full sun. Trichome removal from leaf surfaces of plants grown in full sun, using adhesive tape, was effective for S. lichtensteinii, S. mauritianum, and S. melongena, but not S. tuberosum. Leaf consumption by C. hybrida increased significantly where manual trichome removal using adhesive tape was effective. Structurally, leaves of S. tuberosum have simple trichomes with basal cells sunken into the mesophyll tissue. When using forceps to remove trichomes of S. tuberosum, mesophyll and vascular tissue remained attached to the trichomes. Generally, the type, density, and mat-thickness of leaf trichomes determined feeding by C. hybrida, but varied with plant species and growth conditions.
生长条件介导的植物形态变化与食草动物寄主偏好的变化有关。了解这些形态变化如何影响食草动物的取食，对于解释检疫中候选杂草生物防治剂的寄主评估结果以及改进评估系统至关重要。我们确定了植物生长条件对叶毛状体以及Conchyloctenia hybrida Boheman寄主选择的影响，Conchyloctenia hybrida Boheman是一种在取食前会去除毛状体的昆虫。该研究包括四种茄属植物：lichtensteinii茄（Conchyloctenia hybrida的天然寄主）、mauritianum茄、melongena茄和tuberosum茄。植物分别种植在全日照、遮荫、温室或生长室中。在全日照下生长的植物比在遮荫或受控环境中的植物具有更高的叶毛状体密度。mauritianum茄的毛状体密度和毛状体层厚度最高。在使用离体叶片的多项选择试验中，与全日照相比，Conchyloctenia hybrida在受控环境中生长的茄属植物上的取食量更高。使用胶带去除全日照下生长的植物叶片表面的毛状体，对lichtensteinii茄、mauritianum茄和melongena茄有效，但对tuberosum茄无效。在使用胶带手动去除毛状体有效的情况下，Conchyloctenia hybrida的叶片消耗量显著增加。从结构上看，tuberosum茄的叶片具有简单的毛状体，基部细胞沉入叶肉组织中。当使用镊子去除tuberosum茄的毛状体时，叶肉和维管组织仍附着在毛状体上。一般来说，叶毛状体的类型、密度和垫厚度决定了Conchyloctenia hybrida的取食情况，但因植物种类和生长条件而异。
