暗黑鳃金龟对于半腐熟有机物产卵偏好性的生态学机制

The dark black chafer Holotrichia parallela Motschulsky, is the dominate species among white grubs which is a major group of underground pests. It has a wide host range, long life cycle and lives in soil during its larva stages, so it’s difficult to control in juvenile than adult. H. parallela shifts hosts between larva and adult, and there is a strong ovipositional preference upon Partially Decomposed Organic matters (PDO) for its adult. It’s common for scarab beetles of the Scarabaeoidea superfamily to prefer laying eggs in PDO. However, the mechanism underlying this special ovipositional preference has not yet been elucidated. Based on present evidences, we speculate that this trait is evolved to maximize the performance of its offspring. To test this hypothesis, we use H. parallela as a model insect to systematically investigate its adults’ ovipositional choice among different PDO stages as well as the effect of ovipositional choice on the performance of its larvae. At the same time, we try to isolate and figure out which kind(s) of volatile is (are) responsible for the attraction of ovipostion by H. parallela adults in the PDO, employing modern chemical ecological techniques. After which, the behavioral effects of the bioactive compounds on H. parallela will be tested in laboratory and the filed. By conducting this project, there is a significance both in theory and practice, that is, it helps to validate the “Preference – Performance Hyphthosis” on underground insects, and lead to the development of a new ovipositional attractant to lure and kill gravid adults of scarab beetles, which helps to build an integrated management system for underground pests.

暗黑鳃金龟是我国最主要的地下害虫类群蛴螬的优势种，其幼虫期在土壤中隐蔽为害，防治难度大，而成虫期防治事半功倍。暗黑鳃金龟成虫和幼虫寄主不同，对于半腐熟有机物有强烈的产卵偏好性。趋向于腐败的有机物产卵的现象在金龟子类昆虫中比较普遍，但目前缺乏系统深入的研究。根据已有报道我们推测：金龟子对于半腐熟有机物产卵偏好可能有利于提高其后代适合度。为验证此假设，本项目拟以暗黑鳃金龟为研究对象，系统研究其成虫对于不同腐熟程度有机物的产卵选择行为以及成虫产卵偏好性对幼虫适合度的影响；同时，运用化学生态学手段，分离筛选半腐熟有机物中吸引暗黑鳃金龟成虫产卵的活性化合物，并进行室内行为学验证和田间诱集实验。本项目研究不仅在解释金龟子成虫这一特殊产卵偏好性的生态学意义以及验证和丰富 “偏好-表现”生态学假说方面有重要的理论意义，而且在研发新型金龟子产卵引诱剂，进一步完善地下害虫绿色防控体系方面有重要的实践意义。

暗黑鳃金龟是重要地下害虫蛴螬的优势种之一，其幼虫期在土壤中隐蔽为害，防治难度大；成虫期出土活动，防治成本低。暗黑鳃金龟成虫和幼虫寄主不同，且对于半腐熟有机物有强烈的产卵偏好性，但其生态学和化学生态学机制尚不明确。..本项目通过室内和田间试验，研究暗黑鳃金龟成虫对于不同腐熟程度有机物的产卵选择行为以及成虫产卵偏好性对幼虫适合度的影响；同时，运用化学生态学手段，分离筛选半腐熟有机物中吸引暗黑鳃金龟成虫产卵的活性化合物，并进行室内行为学验证和田间诱集实验。..项目获得以下研究进展：①半腐熟的有机物对金龟子产卵有显著的引诱作用。无论是植物源还是动物源有机肥，半腐熟处理均显著高于完全腐熟处理；完全腐熟的植物源有机肥与对照土壤相比没有显著差异。②腐败有机物虽然对孵化率影响不显著，但可显著提高1龄幼虫的存活率，且完全腐熟有机物对存活率的促进更显著。③试图从不同腐熟程度的有机物中提取挥发物成分，并通过GC-MS鉴定成分。鉴定出butyric acid, p-cresol, indole, isoberneol, formaldehyde, 1-hexanol, pinene, cis-hexen-1-ol, campephene, estragol等化合物，并进行了室内行为学验证。室内初步试验表明， campephene, estragole, folmaldehyde等对成虫产卵有引诱作用。④ 此外还研究了暗黑鳃金龟对不同寄主植物的产卵偏好性。室内和田间试验均表明，暗黑鳃金龟成虫对三种寄主植物的产卵偏好顺序依次为花生≥大豆＞玉米。..本项目以实验方式证实了暗黑鳃金龟成虫对于半腐熟有机物存在显著的产卵偏好性，明确了幼虫在含腐败物质的环境中有更佳的表现，验证并丰富了“偏好-表现”生态学假说。同时提取鉴定了产卵引诱活性化合物，为研发新型金龟子产卵引诱剂提供了理论基础。