铁冬青花挥发性化合物对中华蜜蜂访花的影响

Effects of volatile organic components of Ilex rotunda on its insect pollinator,Apis cerana

【目的】检测铁冬青(Ilex rotunda)雌株和雄株开花进程中挥发性成分的种类差异和动态,观察传粉昆虫的种类及行为,明确铁冬青传粉系统特性,探究其挥发性成分的变化规律对传粉昆虫行为的潜在影响,为提高铁冬青授粉效率及其观赏利用价值提供参考。【方法】利用顶空固相微萃取(HS-SPME)和气相色谱-质谱联用(GC-MS)技术分析铁冬青大蕾期、初绽期、盛开期、末花期4个阶段花挥发性成分的变化;采用观测法,记录传粉昆虫的种类、访问频次,分析昆虫的访花行为及访花频率变化规律。【结果】(1)铁冬青花期共检测出30种挥发性物质,其中雌花检测出19种,雄花检测出21种。(2)挥发性成分中,β-石竹烯等主要成分含量的变化规律是先上升后降低,在盛花期达到峰值。末花期主成分的含量占比普遍降低,醇类、烷烃类的占比有所上升,伴随出现罗勒烯等多种新化合物。(3)铁冬青的授粉昆虫较为单一,为中华蜜蜂(Apis cerana),雌株与雄株的访问高峰期高度重叠,中华蜜蜂更倾向于访问雄花,其访花频率的变化趋势与β-石竹烯含量变化规律一致。【结论】推测β-石竹烯可能作为一种信息物质吸引中华蜜蜂进行授粉;利用中华蜜蜂“集中式”的访花模式,集中且合理搭配栽植铁冬青雌雄株,配合花期一致、雄株花量大的规律,可有效提高提冬青的授粉成功率。

【Objective】The relationship between odorous substances in flowers and the visiting behavior of insects has attracted increasing attention from biologists.However,previous studies on specific plants and pollinators are scare.The present study investigated the species differences and dynamic changes in the volatile organic components of male and female flowers of Ilex rotunda during flowering,and recorded the species and behaviors of pollinators.The study aimed to elucidate the characteristics of the pollinating system,explore the potential effects of volatile compounds on the behaviors of pollinating insects,and provide a reference for improving the pollination and fruiting of I.rotunda.【Method】The changes in the volatile components during the four flowering stages,the big bud stage,first blooming stage,full blooming stage,and final flowering stage,were determined by head space solid phase microextraction(HS-SPME)and gas chromatography-mass spectrometry(GC-MS).The species,visiting behavior,and visiting frequency of the pollinators were recorded by observation.【Result】The results demonstrated that the flowering of I.rotunda began in late April and ended in early May in Nanjing,with a flowering period of nearly half a month.A total of 30 volatile substances were detected from the flowers,of which 19 and 21 were detected from female and male flowers,respectively.There was a moderate difference in the overall number of male and female plants.The results revealed that the levels ofβ-caryophyllene and other major components increased initially,reached a peak at the full-opening stage,and decreased thereafter.The proportion of the main components generally decreased at the final flowering stage.However,there was an increase in the proportion of alcohols and alkanes during final flowering,which was accompanied by the production of several new compounds.The sole insect pollinator of I.rotunda is Apis cerana.There was a considerable overlap between male and female plants during the peak visiting period.The findings revealed that A.cerana preferred visiting male flowers,and that there was a positive correlation between the changes in the visiting frequency pattern andβ-caryophyllene content.【Conclusion】The results indicated thatβ-caryophyllene could be used as an information substance to attract A.cerana for pollinating I.rotunda.Additionally,male and female I.rotunda plants can be planted in a centralized and reasonable manner according to the“centralized”flower visiting behavior of A.cerana.The success rate of I.rotunda pollination can be effectively improved by complying with the consistent flowering period,the concentrated flowering period,and planting large numbers of male plants.