蛀干害虫云斑白条天牛的寄主专化性及其分化形成机制

Batocera lineolata Chevrolat (Coleoptera: Cerambycidae) is a serious pest of forest, with larvae boring into tree trunks, so that it is difficult to control. However, it could be controlled effectively by Dastarcus helophorides (Fairmaire) (Coleoptera: Bothrideridae), an important parasitoid natural enemy. It was found by previous survey that B. lineolata mainly attacked ashe trees in the Yellow River Delta and poplars in Middle-Lower Yangtze River,showing preference for different hosts, and the parasitic effects was different after releasing D. helophorides. According to the foundations, it was infered the difference of the parasitic effects of D. helophorides was caused by host specialization of B. lineolata. Therefore, the accuracy of the hypothesis have been very important basic problem for biocontrol B. lineolata..In order to confirm the above hypothesis, the research project will be carried out based on previus results, as the study object is B. lineolata attacking poplars and ashe trees. By rearing trial pest exchanging natural host, it will be studied the host specialization of B. lineolata larva for boring hosts and adults for complementary nutrition. And the B. lineolata host specialization differentiation degree will be given according to the fertility of hybridization F1 generation. The formation mechanism of host specialization will be revealed by analysing adaptive changes, according to the difference on morphological characteristics, ecological behaviour, nutrition ingredient, and gene of B. lineolata attacking poplars and ash trees. The study results have important guiding value for increasing effect of bioncotrol B. lineolata by releasing D. helophorides. Meanwhile, there is major theoretical significance for the study on co-evolutionary of pest-host and species formation mechanism.

云斑白条天牛是我国重要林木蛀干害虫，防治十分困难，天敌花绒寄甲有较好的防控效果。前期研究发现，危害白蜡树和杨树的云斑白条天牛种群存在明显的取食偏好，不能相互建立种群，遗传结构也有差异，且同一生物型花绒寄甲的寄生效果也不同，推测云斑白条天牛具有寄主专化性，这一推断是否科学，已成为云斑白条天牛生物防治过程中亟待解决的基础问题。本项目以危害白蜡和杨树云斑白条天牛种群为研究对象，通过交换寄主饲养，解析幼虫对蛀食寄主、成虫对补充营养寄主的专化性；从分子水平明确遗传结构的差异；观察杂交F1代是否可育，明确不同寄主种群间的分化程度。根据危害白蜡和杨树云斑白条天牛种群在形态、生态、营养、生殖和遗传等方面的差异，分析其对嗜好寄主的适应性，揭示寄主专化性的形成机制。研究成果为生产中选择寄生率高的花绒寄甲防治危害不同寄主的云斑白条天牛提供理论指导，同时对害虫-寄主的协同进化、物种形成等研究也有重要理论意义。

云斑白条天牛是我国重要林业蛀干害虫，调查研究难度较大。本项目以危害白蜡和杨树云斑白条天牛种群为研究对象，研究发现，交换寄主饲养，卵不能孵化，危害杨树云斑白条天牛幼虫可以取食白蜡树木段，危害白蜡树云班白条天牛幼虫也可以取食杨树木段。补充营养寄主选择习性差异明显，危害白蜡树云斑白条天牛成虫只取食白蜡枝条，危害杨树云斑白条天牛成虫取食核桃、蔷薇枝条，不取食白蜡树枝条。补充营养寄主核桃、蔷薇、白蜡、杨树枝条的游离氨基酸含量不一致。产卵习性也存在明显差别，危害杨树云斑白条天牛成虫产卵部位为红色，危害白蜡树种群成虫产卵部位为淡黄色。两个种群的成虫形态特征有差异，危害白蜡树云斑白条牛触角第10节有齿突，杨树种群不明显；白蜡树种群雌成虫第5腹节有一“V”型纵沟，末节端部管状突出，杨树种群的纵沟呈线状，端部管状延伸不明显；雌成虫产卵器基腹片骨杆、肛侧板、阴道片、受精囊有差异；雄成虫的第八腹节背板形状、阳茎基、中茎基存在差异。两个种群的雌雄个体间的COⅠ、COⅡ、Cyt b、16S rRNA 4个线粒体基因序列存在差异，危害白蜡树云斑白条天牛雌雄成虫间序列相似度依次为98.7%、99.1%、98.4%、98.8%，危害杨树云斑白条天牛依次为98.6%、98.3%、98.9%、99.2%。不同世代个体间的线粒体基因存在差异，危害白蜡树云斑白条天牛种群雌成虫CO I基因在2019年和2014年两个世代间的序列相似度为99.50%，雄成虫为99.20%；危害杨树云斑白条天牛种群雌成虫的序列相似度为99.5%，雄成虫为98.90%。两个寄主种群间4个线粒体基因序列存在差异，CO I基因雌成虫的序列相似度为95.9%，雄成虫为97.3%；CO II基因雌雄成虫均为94.0%；Cyt b基因雌成虫为93.9%，雄成虫为94.5%；16S rRNA基因雌雄成虫均为95.9%。通过以上研究阐明了危害白蜡树和杨树云斑白条天牛种群分化特征和分化机制，对云斑白条天牛的综合防治和昆虫种群分化具有重要理论意义。