豚草生育期和被利用状态对广聚萤叶甲产卵选择的影响

Influence of growth periods and colonization on oviposition selection of Ophraella communa(Coleoptera:Chrysomelidae) on Ambrosia artemisiifolia(Compositae)

【背景】植食性昆虫对产卵场所的选择行为受多种因素的影响,其中寄主植物的发育阶段和被同种其他个体利用程度是影响其产卵选择的重要因素之一。【方法】采用野外罩笼的选择性试验,观察了广聚萤叶甲成虫对不同生长发育阶段、不同被取食程度、不同落卵量的豚草植株的产卵选择行为,分析产卵选择频次,用Cox比例风险模型拟合识别期以估计产卵选择偏好性。【结果】开花期豚草被选择产卵的风险(瞬间概率)仅为生长期的16.5%,苗期豚草被选择产卵的风险为生长期的34.1%;成虫对3种被食程度豚草的产卵选择频次之间存在显著差异(n=20,P<0.01),在3级被食程度豚草上产卵次数最多(12次),而在5级被食豚草上产卵次数最少(2次),表明成虫明显偏好将卵产于已被中等程度取食的植株上;成虫对不同落卵量植株(0、4、8个.株-1)未表现出显著的产卵偏好,对不同密度(高、低)斑块的豚草的产卵选择亦无显著差异。【结论与意义】豚草生育期和被取食程度影响广聚萤叶甲雌虫的产卵选择,而植株上的落卵量和豚草密度对产卵选择没有影响。

[Background]Oviposition site selection in insect herbivores can be influenced by a variety of factors,including development stage and colonization of conspecifics.[Method]Choice trials using field cages were conducted to observe oviposition selection of Ophraella communa on the invasive weed,Ambrosia artemisiifolia of varying plant stage,feeding damage level,and egg-loading level.Frequency of oviposition choices was compared and latency to ovipostion（as measured by recognition time） fitted with Cox proportional hazard model to evaluate host preferences.[Result]Blossoming plants had a lower hazard of being oviposited by O.communa females compared to that in vegetative stage（a difference of 16.5%）,and seedlings also had lower hazard（by 34.1%） vs.the vegetative stage.Adults chose to selectively oviposit according to different levels of feeding damage（n=20,P0.01）,with more oviposition choices（12） for the plant at the intermediate level（rank 3） and avoiding heavily（rank 5） damaged plants.O.communa females laid similar number of eggs on plants carrying no eggs,four,or eight egg-masses,neither showed preferences between plant patches of the low vs.high densities.[Conclusion and significance]Plant growth periods and the extent of feeding damage exercised obvious influences on oviposition selection,but egg densities or density of plants did not affect oviposition choices.