Gandolfi Michela, Mattiacci Letizia, Dorn Silvia
Institute of Plant Sciences/Applied Entomology, Swiss Federal Institute of Technology (ETH), Clausiusstrasse 25/NW CH-8092 Zurich, Switzerland.
J Chem Ecol. 2003 Aug;29(8):1871-87. doi: 10.1023/a:1024854312528.
A high quality of mass reared parasitoids is required for successful biological control of pest insects. Although the phenomenon of behavioral deterioration of parasitoids due to rearing in artificial conditions is well known, its significance is often underestimated, and the underlying mechanisms are poorly investigated. We quantified behavioral alterations of parasitoids reared in an artificial system vs. a natural system and elucidated some of the mechanisms involved. The model systems consisted of apple fruits (natural system) or an artificial diet devoid of apple (artificial system), the herbivore Cydia pomonella, and its larval parasitoid Hyssopus pallidus, a candidate biological control agent. Two parasitoid strains, one reared for 30 generations in the natural system and one in the artificial system, were compared by using the females' ability to respond to frass from codling moth caterpillars fed on apple fruits (apple-frass). The searching response of parasitoids reared in the artificial system compared to those reared in the natural system was reduced by an average of 53.2%. Gas chromatography-mass spectrometry (GC-MS) analyses of the two types of caterpillars' food and of the two corresponding types of frass showed that 15 compounds were present only in apple fruits and apple-frass, three compounds only in artificial diet and artificial-diet-frass, while four compounds were present in both frass types but not in the food sources. This suggests the presence of a food-derived and a host-derived component in the frass. Results from both bioassays and chemical analyses indicate that the kairomonal activity of the frass is due to both apple fruit and host components. The reduced response of parasitoids reared in artificial conditions might, therefore, be due to a lack of recognition of the apple fruit component. In a further experiment, the two parasitoid strains were reared in the opposite system for one generation. While the response to the host frass was significantly reduced in parasitoids that emerged from the artificial system, it was fully restored in parasitoids that emerged from the natural system. This indicates that the behavioral alteration was related to a learning process during ontogenesis rather than to a selection exhibited over generations.
为了成功地对害虫进行生物防治，需要高质量大量饲养的寄生蜂。尽管由于在人工条件下饲养而导致寄生蜂行为退化的现象广为人知，但其重要性往往被低估，其潜在机制也鲜有研究。我们量化了在人工系统与自然系统中饲养的寄生蜂的行为变化，并阐明了其中一些相关机制。模型系统由苹果果实（自然系统）或不含苹果的人工饲料（人工系统）、植食性昆虫苹果蠹蛾及其幼虫寄生蜂苍白神香草（一种候选生物防治剂）组成。通过比较两种寄生蜂品系（一种在自然系统中饲养30代，另一种在人工系统中饲养）的雌蜂对取食苹果果实的苹果蠹蛾幼虫粪便（苹果粪便）的反应能力，对它们进行了比较。与在自然系统中饲养的寄生蜂相比，在人工系统中饲养的寄生蜂的搜索反应平均降低了53.2%。对两种类型的毛虫食物和两种相应类型的粪便进行气相色谱-质谱（GC-MS）分析表明，有15种化合物仅存在于苹果果实和苹果粪便中，3种化合物仅存在于人工饲料和人工饲料粪便中，而有4种化合物在两种粪便类型中都存在，但在食物来源中不存在。这表明粪便中存在食物来源和寄主来源的成分。生物测定和化学分析的结果均表明，粪便的利它素活性归因于苹果果实和寄主成分。因此，在人工条件下饲养的寄生蜂反应降低可能是由于缺乏对苹果果实成分的识别。在进一步的实验中，将两种寄生蜂品系在相反的系统中饲养一代。虽然从人工系统中羽化的寄生蜂对寄主粪便的反应显著降低，但从自然系统中羽化的寄生蜂的反应完全恢复。这表明行为改变与个体发育过程中的学习过程有关，而不是与几代人表现出的选择有关。
