基于枣树挥发物主导的枣飞象寄主定向化学通讯机制研究

Scythropus yasumatsui, one of the most serious pests on Chinese jujube tree (Zizyphus jujube Mill), has recently erupted on Chinese jujube tree in northern Shaanxi provinces. The eruption of S. yasumatsui causes a serious damage on local economy. Therefore, it is necessary to uncover the underlying mechanisms. Our previous study found that the volatiles emitted from Chinese jujube tree play a key role in mediating the host location of S. yasumatsui. However, until now little is known about the chemical communication mechanism involved in the host location of S. yasumatsui. In the present study, we employed S. yasumatsui and local species of Chinese jujube tree in northern Shaanxi provinces as model system. Firstly, the preference of S. yasumatsui to different species of Chinese jujube tree was determined by olfactory bioassay and oviposition choice experiment, thereby screening the preferred host species. After that, the volatiles emitted from S. yasumatsui preferred Chinese jujube trees are collected. The potential compounds that are attractive to S. yasumatsui are identified by GC-MS, GC-EAD, EAG, and olfactometers. By analyzing these data, we expected to explore the relationship between the volatile compounds and host location behavior of S. yasumatsui, and indentify the effective volatile compounds that are attractant to S. yasumatsui. Finally, the effects of effective volatile compounds were examined by laboratory bioassay and trap assay in field, respectively. Our results will advance our understanding of the mechanism involved in chemical communication between Chinese jujube tree and S. yasumatsui during host location by S. yasumatsui, and on the other hand, will lay the theoretical foundation for utilizing volatile compounds emitted from Chinese jujube tree as attractants trapping S. yasumatsui in field.

枣飞象是枣树重要害虫之一，近年来在我国陕北枣区爆发成灾，严重影响区域经济发展，迫切需要对其危害机理进行深入研究。申请者前期研究发现枣树挥发物在枣飞象寄主定位过程中起关键作用，但目前关于枣飞象寄主定向化学通讯机理尚缺乏可解释的理论依据。本项目拟以枣飞象和陕北地区的主要枣树品种为研究对象，通过室内嗅觉生测和产卵试验，研究枣树品种间嗅觉和产卵偏好性差异，筛选出枣飞象显著偏好的枣树品种；通过动态顶空和微固相萃取收集枣飞象偏好枣树品种的挥发物，利用GC-MS、GC-EAD、EAG和嗅觉仪，研究枣飞象寄定位与枣树信息化学物质的关系，鉴定出对枣飞象具有引诱作用的特异性信息物质；通过室内可控条件试验结合田间试验研究枣树特异性信息化学物质对枣飞象引诱作用，为揭示枣飞象寄主定向化学通讯机理和田间有效防控提供理论依据。

枣飞象是枣树的重要害虫，在陕北枣区暴发成灾，造成了严重的经济和生态损失。目前关于枣飞象寄主定向的化学通讯机制尚不清楚。本项目通过室内嗅觉、产卵和饲养试验，发现木枣、狗头枣、赞皇枣、骏枣和酸枣的枣芽挥发物对枣飞象都有明显吸引作用，枣飞象产卵偏好品种为木枣，其次为狗头枣和骏枣；5种枣树均适合成虫繁殖，木枣为最适的枣树品种。利用顶空吸附法收集上述5种枣树的枣芽挥发物，采用气质联用仪(GC-MS)进行化学指纹谱的鉴定和分析，共鉴定出挥发性物质6类26种，包括9种萜烯类、6种酯类、4种醇类、4种烷类、2种醛类和1种酚类，不同品种枣芽挥发性物质种类和含量存在差异。利用触角电位技术(EAG)研究枣飞象对24种枣树挥发性物质的触角电位反应，发现枣飞象对罗勒烯、蒈烯、α-水芹烯、α-法呢烯、反-2-己烯醇、乙酸正丁酯、桉叶油醇、D-柠檬烯、正十三烷、正十四烷、正十五烷、壬醛、棕榈酸甲酯和油酸甲酯14种挥发性物质的具有较强的EAG反应，当挥发性物质浓度为0.1~100μg/μL时，随着浓度增加，枣飞象成虫EAG反应相对值先增加后下降，当刺激浓度为50μg/μL时EAG反应相对值达到最大。利用Y型嗅觉仪研究了枣飞象对这14种挥发物的行为反应，发现罗勒烯、α-法呢烯、棕榈酸甲酯和壬醛对枣飞象雌雄成虫均有明显吸引作用。通过室内和田间诱集试验，筛选获得了罗勒烯:α-法呢烯=1:1以及罗勒烯:α-法呢烯:棕榈酸甲酯:壬醛=1:1:1:2的引诱剂对枣飞象有明显诱集作用。此外，发现粘虫板颜色为黄绿色，悬挂高度为距离地面0.8m，悬挂方位为正南方、悬挂密度为20张/667m2的试验组合对枣飞象成虫诱集效果最好，可用于田间诱杀枣飞象。本项目不仅揭示了枣飞象寄主定向的化学通讯机理，而且为枣飞象绿色防控提供了新思路和方法。