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摘要 昆虫的种群动态和数量分布与环境因素密切相关。本研究通过在中国南方空心莲子草大规模入侵的区域分别设置水、陆样地,采用曲线回归和冗余分析等方法探讨了异质生境中空心莲子草形态特征、入侵群落植物多样性及无机环境对生防昆虫莲草直胸跳甲数量分布的影响。结果显示:水、陆两境中莲草直胸跳甲数量均随着空心莲子草株高增加而上升;莲草直胸跳甲数量随水生型空心莲子草分枝数及入侵盖度的增加而上升。莲草直胸跳甲数量与陆生群落植物物种多样性无显著相关性,但在水生环境中,莲草直胸跳甲数量随群落的Simpson、Shannon和Pielou指数上升而显著下降。水、陆两境中决定莲草直胸跳甲数量的主导性环境因子均为年均气温、纬度和海拔。研究结果可为入侵植物的生物防治及引进天敌提供参考。
关键词 环境因子; 莲草直胸跳甲; 种群数量; 生物入侵; 冗余分析
中图分类号: S 476
文献标识码: ADOI: 10.16688/j.zwbh.2018246
Abstract The insect population dynamics and quantity distribution are closely related to environmental factors. In this study, we set up aquatic and terrestrial plots in locations that were invaded largely by alien Alternanthera philoxeroides in Southern China, by using the curvilinear regression and redundancy analysis methods; we analyzed the influences of A.philoxeroides morphological characteristics, plant species diversity within invaded community and inorganic environmental factors on the population abundance of an biocontrol insect Agasicles hygrophila in heterogeneous habitats. The results showed that the A. hygrophila abundance increased with the increasing A.philoxeroides height in both aquatic and terrestrial habitats, and increased with A.philoxeroides branches and invasion coverage only in the aquatic habitat. The A.hygrophila abundance had no significant relationships with the terrestrial plant species diversity; however, it significantly decreased with the rising Simpson, Shannon, Pielou indices in aquatic invaded plant community. In addition, the dominant environmental factors which determined the A.hygrophila abundance were annual mean temperature, latitude and elevation in both aquatic and terrestrial habitats. Our research could provide suggestive references for biological control of invasive plants and introduction of natural enemies.
Key words environmental factor; Agasicles hygrophila; population abundance; biological invasion; RDA
昆蟲作为自然界数量最多的动物占据着各类微生境,其对环境变化敏感,昆虫种群的分布与环境关系极为紧密[13];分析昆虫生境因子(生物、非生物)耦合关系对于研究昆虫、防治昆虫或培养利用昆虫具有重要指导意义[4]。以往研究表明,水温、总磷、氨态氮、海拔和溶解氧等环境驱动因子在不同程度上影响水生昆虫群落结构及其多样性[56]。同时,昆虫分布状况也受到生境中植物群落特征的影响,如:在长白山阔叶红松林中,植食性昆虫丰富度与植物群落物种丰富度呈负相关,植食性昆虫类群主要依靠草本的复杂性和多样性[7];而在油松林中,随着植物群落科种组成复杂程度的增加,昆虫群落的多样性增加[8]。此外,郭海滨等关于草坪昆虫群落的研究表明,植食性害虫的分布与杂草种类及草坪高度呈负向关系[9]。在全球环境迅速变化的背景下,探讨昆虫(尤其是天敌昆虫)的数量分布规律及其关键性影响因子,有助于维护农业生态系统稳定性及保障国家生物安全[10]。
莲草直胸跳甲Agasicles hygrophila又名喜旱莲子草叶甲、曲纹叶甲,属鞘翅目叶甲科跳甲亚科。其起源于南美洲,取食空心莲子草Alternanthera philoxeroides叶片及上部嫩叶茎,幼虫钻入茎秆后化蛹并分泌有毒物质阻止节间生长。莲草直胸跳甲于1986 年从美国佛罗里达引入中国,是防治入侵植物空心莲子草最有效的专食性天敌昆虫[11]。近期,在宏观水平上关于莲草直胸跳甲的研究主要集中于生物学特征、繁殖技术及其生防效果评估等方面,如:前人研究表明,莲草直胸跳甲在旱地的扩散能力强于湿地[12];适当延长光周期的光照时数可提高莲草直胸跳甲幼虫的存活率[13];在有限的空间及资源条件下,每头莲草直胸跳甲成虫所需的最适空间约为31.25 cm3[14];生境中的养分富集会导致空心莲子草对莲草直胸跳甲取食的诱导抗性增加,从而降低莲草直胸跳甲的生防效应[15]。 尽管诸多研究已表明环境异质性是决定群落结构和生态系统健康的重要因素[16],但迄今为止,关于大尺度地理格局上“环境因子莲草直胸跳甲种群分布”的研究尚未见报道。本研究通过大尺度的野外调查,对比分析了水生及陆生型空心莲子草入侵群落中莲草直胸跳甲数量的差异,并分别从无机生境因子、入侵群落植物多样性、空心莲子草种群特征等方面探讨其对莲草直胸跳甲数量的影响,以期阐明莲草直胸跳甲在异质生境中的分布规律及其主导性因素,为入侵植物的生物防治及评估天敌昆虫的生防效应提供依据。
1 材料与方法
1.1 野外调查
2014年7-8月,在中国南方21°N~31°N纬度范围内,选择空心莲子草入侵面积
关键词 环境因子; 莲草直胸跳甲; 种群数量; 生物入侵; 冗余分析
中图分类号: S 476
文献标识码: ADOI: 10.16688/j.zwbh.2018246
Abstract The insect population dynamics and quantity distribution are closely related to environmental factors. In this study, we set up aquatic and terrestrial plots in locations that were invaded largely by alien Alternanthera philoxeroides in Southern China, by using the curvilinear regression and redundancy analysis methods; we analyzed the influences of A.philoxeroides morphological characteristics, plant species diversity within invaded community and inorganic environmental factors on the population abundance of an biocontrol insect Agasicles hygrophila in heterogeneous habitats. The results showed that the A. hygrophila abundance increased with the increasing A.philoxeroides height in both aquatic and terrestrial habitats, and increased with A.philoxeroides branches and invasion coverage only in the aquatic habitat. The A.hygrophila abundance had no significant relationships with the terrestrial plant species diversity; however, it significantly decreased with the rising Simpson, Shannon, Pielou indices in aquatic invaded plant community. In addition, the dominant environmental factors which determined the A.hygrophila abundance were annual mean temperature, latitude and elevation in both aquatic and terrestrial habitats. Our research could provide suggestive references for biological control of invasive plants and introduction of natural enemies.
Key words environmental factor; Agasicles hygrophila; population abundance; biological invasion; RDA
昆蟲作为自然界数量最多的动物占据着各类微生境,其对环境变化敏感,昆虫种群的分布与环境关系极为紧密[13];分析昆虫生境因子(生物、非生物)耦合关系对于研究昆虫、防治昆虫或培养利用昆虫具有重要指导意义[4]。以往研究表明,水温、总磷、氨态氮、海拔和溶解氧等环境驱动因子在不同程度上影响水生昆虫群落结构及其多样性[56]。同时,昆虫分布状况也受到生境中植物群落特征的影响,如:在长白山阔叶红松林中,植食性昆虫丰富度与植物群落物种丰富度呈负相关,植食性昆虫类群主要依靠草本的复杂性和多样性[7];而在油松林中,随着植物群落科种组成复杂程度的增加,昆虫群落的多样性增加[8]。此外,郭海滨等关于草坪昆虫群落的研究表明,植食性害虫的分布与杂草种类及草坪高度呈负向关系[9]。在全球环境迅速变化的背景下,探讨昆虫(尤其是天敌昆虫)的数量分布规律及其关键性影响因子,有助于维护农业生态系统稳定性及保障国家生物安全[10]。
莲草直胸跳甲Agasicles hygrophila又名喜旱莲子草叶甲、曲纹叶甲,属鞘翅目叶甲科跳甲亚科。其起源于南美洲,取食空心莲子草Alternanthera philoxeroides叶片及上部嫩叶茎,幼虫钻入茎秆后化蛹并分泌有毒物质阻止节间生长。莲草直胸跳甲于1986 年从美国佛罗里达引入中国,是防治入侵植物空心莲子草最有效的专食性天敌昆虫[11]。近期,在宏观水平上关于莲草直胸跳甲的研究主要集中于生物学特征、繁殖技术及其生防效果评估等方面,如:前人研究表明,莲草直胸跳甲在旱地的扩散能力强于湿地[12];适当延长光周期的光照时数可提高莲草直胸跳甲幼虫的存活率[13];在有限的空间及资源条件下,每头莲草直胸跳甲成虫所需的最适空间约为31.25 cm3[14];生境中的养分富集会导致空心莲子草对莲草直胸跳甲取食的诱导抗性增加,从而降低莲草直胸跳甲的生防效应[15]。 尽管诸多研究已表明环境异质性是决定群落结构和生态系统健康的重要因素[16],但迄今为止,关于大尺度地理格局上“环境因子莲草直胸跳甲种群分布”的研究尚未见报道。本研究通过大尺度的野外调查,对比分析了水生及陆生型空心莲子草入侵群落中莲草直胸跳甲数量的差异,并分别从无机生境因子、入侵群落植物多样性、空心莲子草种群特征等方面探讨其对莲草直胸跳甲数量的影响,以期阐明莲草直胸跳甲在异质生境中的分布规律及其主导性因素,为入侵植物的生物防治及评估天敌昆虫的生防效应提供依据。
1 材料与方法
1.1 野外调查
2014年7-8月,在中国南方21°N~31°N纬度范围内,选择空心莲子草入侵面积