Colazza Stefano, Lo Bue Mauro, Lo Giudice Daniela, Peri Ezio
Department of S.En.Fi.Mi.Zo.-Entomology, Acarology and Zoology, Università degli Studi di Palermo, 13 viale delle Scienze, 90128, Palermo, Italy.
Naturwissenschaften. 2009 Aug;96(8):975-81. doi: 10.1007/s00114-009-0548-3. Epub 2009 May 20.
Chemical footprints left behind by true bugs are perceived as contact kairomones by scelionid egg parasitoids. Female wasps encountering a contaminated artificial substrate display a characteristic arrestment posture, holding the body motionless and antennating the surface. In the system Nezara viridula (L.) and its egg parasitoid Trissolcus basalis (Wollaston), previous studies have shown that the kairomone mediating such behavior is part of N. viridula's cuticular hydrocarbons (CHC) and furthermore that the wasp's ability to discriminate host male and female footprints is mainly based on the presence/absence of nonadecane (nC(19)). In this study, the effect of epicuticular waxes of leaves of broad bean, Vicia faba, on wasp responses to footprints of N. viridula females were investigated. Approximately 20% of T. basalis females displayed an arrestment posture when released on the adaxial leaf surfaces of broad bean plants with intact wax layer and without host chemical contamination; whereas approximately 70% of wasps displayed the arrestment posture when intact leaves were contaminated by host female footprints. Adaxial leaf surfaces of broad bean plants dewaxed with an aqueous solution of gum arabic and afterwards contaminated by N. viridula females induced arrestment responses in about 10% of female wasps; the same percentage of arrestment (10%) was observed when the wasps were released on leaves contaminated by host females and subsequently dewaxed. The side of the polymer film that was appressed to the leaf surface, peeled from the contaminated leaves, induced an arrestment posture in about 95% of observed wasps. Scanning electron microscopy (SEM) revealed that the epicuticular waxes occurred as a film densely crystallized as irregularly shaped platelets with spherical granules randomly distributed. These findings demonstrated that epicuticular waxes of broad bean leaves can mediate the foraging behavior of T. basalis females by absorbing contact kairomones of the host.
椿象留下的化学痕迹被缘腹卵寄生蜂视为接触利它素。遇到受污染人工基质的雌蜂会呈现出一种典型的停留姿势，身体静止不动，用触角触碰表面。在绿蝽（Nezara viridula (L.)）及其卵寄生蜂基底三叉蚜小蜂（Trissolcus basalis (Wollaston)）的系统中，先前的研究表明，介导这种行为的利它素是绿蝽表皮碳氢化合物（CHC）的一部分，此外，黄蜂区分寄主雄雌足迹的能力主要基于十九烷（nC(19)）的有无。在本研究中，调查了蚕豆（Vicia faba）叶片的表皮蜡质对黄蜂对绿蝽雌虫足迹反应的影响。当释放到蜡层完整且无寄主化学污染的蚕豆植株近轴叶表面时，约20%的基底三叉蚜小蜂雌蜂呈现停留姿势；而当完整叶片被寄主雌虫足迹污染时，约70%的黄蜂呈现停留姿势。用阿拉伯胶水溶液对蚕豆植株的近轴叶表面进行脱蜡处理，然后被绿蝽雌虫污染，约10%的雌蜂出现停留反应；当黄蜂释放到被寄主雌虫污染并随后脱蜡的叶片上时，观察到相同比例（10%）的停留反应。从受污染叶片上剥离并压在叶表面的聚合物薄膜一侧，在约95%的观察到的黄蜂中诱发了停留姿势。扫描电子显微镜（SEM）显示，表皮蜡质呈现为一层密集结晶的薄膜，由不规则形状的薄片组成，球形颗粒随机分布。这些发现表明，蚕豆叶片的表皮蜡质可以通过吸收寄主的接触利它素介导基底三叉蚜小蜂雌蜂的觅食行为。
