冀中农区大草蛉（Chrysopa septempunctata）栖息地选择

大草蛉（Chrysopa septempunctata）是华北农区的主要天敌昆虫,研究了作物主要生长季节大草蛉的分布动态及其对栖息地的选择取向,结果表明,(1)大草蛉对栖息生境有较强的选择性,明显趋向于田间杂草地生境;(2)大草蛉在田间草地带上的栖息较为稳定,且受田间草地带宽度的直接影响,宽度1 m左右的草地带有更高的大草蛉密度;(3)林带对大草蛉分布显示出积极作用,其效应范围因林带结构不同表现各异;(4)作物生长后期林带逐渐成为大草蛉栖息的重要场所。     

农林复合环境大草蛉生境选择取向及天敌效能

大草蛉(Chrysopa pallens Rambur)是华北农区优势天敌昆虫之一。华北农区农林复合系统中作物农田、林带所组成的农林生境,就其中的大草蛉对栖息环境、产卵地点、越冬场所等不同生境的选择取向及天敌追随效能展开了多角度研究,结果表明:(1)大草蛉成虫对作物蚜虫具有明显的追随效应,其幼虫对作物蚜虫的空间跟随作用显著,且在不同空间层次均有控制作物蚜虫的表现(空间重叠度指数:P_(幼空间)0.65);大草蛉的采食虫态期与蚜虫的发生期同步(时间重叠度指数:P_(幼空间)0.65)。(2)紧邻农田的林带环境是秋收后大草蛉主要的越冬场所(差异显著性比较:P=0.0010.05,α=0.05),对维系大草蛉在农林生境中的种群延续具有重要作用。(3)大草蛉在林带内的树皮裂缝、地表土层、枯枝落叶下结茧化蛹越冬,并对以上3个地点不存在明显选择性(差异显著性比较:P=0.4660.05,α=0.05);(4)大草蛉在栖息生境中具有季节移动性和偏好选择性双重特点:夏秋两季作物生长期内大草蛉从林带迁飞往农田,偏好在大豆、花生田中栖息(LSD法:P=0.0050.01,α=0.01);农作物秋收后及冬春两季大草蛉栖居于林带中,偏好在杨树萌条林内栖息(LSD法:P=0.0020.01,α=0.01);(5)大草蛉对产卵地点具有选择性,因生境不同表现出一定差异性:在农田生境,大草蛉产卵时节贯穿6至9月,且偏好于花生与玉米田(LSD法:P=0.0070.01,α=0.01);在林带生境,杨树杂木林内具有更高密度卵量(LSD法:P=0.0380.05,α=0.05),产卵时节集中在5至7月。     

冀中农林复合环境瓢虫资源及优势种种群动态

瓢虫科(Coccinellidae)昆虫大多为捕食性种类,其中一些种类是农区重要的天敌昆虫.针对华北冀中农林复合环境瓢虫种群在作物生长期的分布动态与空间格局、以及瓢虫优势种群对栖息地的选择趋向进行了研究,结果表明:(1)林带在作物生长早期是瓢虫赖以生存的主要生境,是后继作物环境瓢虫种群建立的"种库";(2)冀中农区瓢虫的优势种为龟纹瓢虫(Propylea japonica);(3)瓢虫种群随季节变化在各生境斑块间有明显的移动现象;(4)龟纹瓢虫种群在作物生长早期呈均匀或随机分布,在作物生长中后期呈密度依赖型聚集分布;(5)间作田成为作物生长后期瓢虫主要的聚集地显示在生境趋向不利时复杂的环境是理想的栖息场所.     

大草蛉对草地贪夜蛾捕食潜能研究

草地贪夜蛾Spodoptera frugiperda JE Smith于2018年底至2019年初入侵我国后,迅速扩散,并在半年内对西南地区的玉米生产造成为害。田间调查和观测研究表明,田间虽然可见该害虫的天敌,但由于天敌种群数量低,无法形成有效控害的模式。为研究大草蛉对草地贪夜蛾的控害潜能,本研究进行了捕食功能反应试验。结果表明,大草蛉成虫对草地贪夜蛾卵以及大草蛉3龄幼虫对草地贪夜蛾1龄幼虫的捕食效应均能够很好的拟合HollingⅡ功能反应模型。其中,大草蛉成虫对贪夜蛾卵的理论日最大捕食量、瞬时攻击率和处理时间分别为1115.56头、1.004和0.0009 d。大草蛉幼虫对贪夜蛾低龄幼虫的理论日最大捕食量、瞬时攻击率和处理时间分别为358头、1.074和0.003 d。结果表明大草蛉具备对草地贪夜蛾卵和低龄幼虫进行有效控害的潜力,为应用天敌昆虫防治草地贪夜蛾提供了理论依据。     

天敌昆虫大草蛉的研究进展与展望

大草蛉Chrysopa pallens(Rambur)是重要的捕食性草蛉种类之一,可捕食蚜虫、叶螨、粉虱、蓟马、鳞翅目卵及幼虫等多种害虫。本文综合分析了国内外近几十年对大草蛉的研究成果,对其生物学、生态学特性进行了归纳,尤其梳理了大草蛉嗅觉趋性行为、滞育特性、人工饲养、田间控害能力等研究热点,并对大草蛉的田间应用前景进行了展望。     

不同虫态及虫龄大草蛉与七星瓢虫之间的集团内互作

【目的】为明确新疆棉田棉蚜Aphis gossypii捕食性天敌之间的集团内捕食效应及其对蚜虫数量的控制作用。【方法】本研究以优势天敌昆虫大草蛉Chrysopa pallens和七星瓢虫Coccinella septempunctata为对象,以棉蚜为猎物,在温室中利用盆栽棉花,首先观察了2种天敌昆虫之间各虫态及虫龄配对的19个处理在无蚜植株上共存24 h后的存活数,然后观察了2种天敌昆虫配对处理下棉苗上棉蚜数量随时间的变化趋势。【结果】在无蚜棉株上2种捕食性天敌昆虫共存24 h后的存活结果表明:(1)在发育阶段相同的配对组合中,若是成虫则均存活,若是1龄幼虫则大草蛉存活较多,若是末龄幼虫则七星瓢虫存活较多;(2)在有卵的组配中,除七星瓢虫卵不被大草蛉成虫所捕食外,其他5个组配处理中卵均被捕食;(3)在有蛹的配对组合中,除七星瓢虫蛹被大草蛉末龄幼虫捕食外,其他处理下蛹均不被捕食;(4)在成虫与幼虫的配对组合中,七星瓢虫成虫捕食较多的大草蛉1龄幼虫,但不捕食大草蛉末龄幼虫,而大草蛉成虫与七星瓢虫1龄或末龄幼虫之间不发生捕食;(5)在不同龄期幼虫的配对组合中,大草蛉末龄幼虫捕食七星瓢虫1龄幼虫,而七星瓢虫末龄幼虫捕食大草蛉1龄幼虫。在有蚜植株上2种捕食性天敌共存对棉蚜数量具有不同的控制作用:(1)2种捕食昆虫的幼虫各自单独存在(对照)下,蚜虫密度随时间而降低;(2)大草蛉幼虫与七星瓢虫幼虫或成虫配对处理下,棉蚜密度随时间而增大;(3)大草蛉成虫与七星瓢虫幼虫或成虫配对处理下,棉蚜密度随时间而减小。【结论】研究结果说明,大草蛉与七星瓢虫之间存在集团内捕食,但2种天敌共存对棉蚜的控制作用取决于大草蛉虫态,若大草蛉为幼虫,可使蚜虫密度增大,若为成虫,则使蚜虫密度减小。     

棉田草蛉发生规律的研究

草蛉成虫和幼虫能捕食粮、棉、果、树、蔬菜等作物上的多种害虫的多种虫态,是较有利用前途的天敌昆虫。为了摸清各种因子对棉田草蛉种群数量的影响,为保护和利用草蛉提供依据,我们从1974至1976年先后在汉阳、天门、广济、襄阳等县,对草蛉的田间生态作了一些调查和观察,现整理于下。     

互花米草入侵对大型底栖动物群落垂直结构的影响

2012年8月,在浙江省玉环县漩门湾国家湿地公园,利用自制分层采样器,以5 cm为单位对0—25 cm泥层进行分层取样,研究潮间带互花米草滩涂和自然滩涂两种生境中大型底栖动物的垂直分布情况,以及互花米草入侵对大型底栖动物垂直结构的影响。两种生境中共获得大型底栖动物40种,其中软体动物18种,甲壳动物13种,环节动物4种,其他类群5种。在自然滩涂生境中获得的物种数为30种,互花米草生境为31种,两种生境的共有种有21种。互花米草和自然滩涂生境平均栖息密度分别为222.6株/m2和1052.8株/m2。研究结果表明:(1)大型底栖动物主要栖息在0—10 cm泥层深度;(2)大型底栖动物群落沿泥层深度存在分层分布现象;(3)互花米草入侵缩短了底栖动物的垂直分布距离,但对其主要栖息深度影响不大;(4)互花米草入侵改变了原来生境特征,导致大型底栖动物的群落结构发生变化。     

三峡库区苏门白酒草(Conyza sumatrensis)化感作用与入侵性研究

为探讨外来种苏门白酒草(Conyza sumatrensis)的入侵机理,在长江三峡工程库区苏门白酒草入侵地,采用生物检测的方法研究开旷荒地、公路边、林缘3种不同生境条件下的苏门白酒草地上部分和地下部分水浸提液的化感作用。研究结果发现:(1)在小白菜(Brassica chinensis)幼苗萌发生长试验中,苏门白酒草地下和地上部分水浸提液对供试种子的萌发以及幼苗的生长主要表现出抑制作用,并随着浸提液浓度的增加,抑制作用增强;(2)在小白菜种子的萌发及幼苗生长各项指标的对比中发现,用各样地的苏门白酒草地上部分水浸提液处理的各组指标之间的差异大于用其地下部分水浸提液处理的各组指标之间的差异,说明对于不同样地的苏门白酒草的入侵力,地上部分的化感作用比地下部分具有更大的贡献力;(3)不同生境的苏门白酒草化感作用存在差异,生于公路边和开旷荒地生境的苏门白酒草地上部分和地下部分的化感作用能力最强,而生于林缘的苏门白酒草地上部分和地下部分的化感作用能力弱,即公路边开旷荒地林缘;(4)不同生境条件下的苏门白酒草化感作用力与本地植物的相对多度存在显著的正相关关系,表明苏门白酒草化感作用的差异是导致它在不同生境间入侵力差异的原因之一;(5)苏门白酒草的化感作用确实存在,也是其入侵成功的重要原因。     

以豆蚜为食物的大草蛉生命表及饥饿对其食物利用率的影响

在温度25℃±1℃、RH 55％±5％、光周期16L:8 D条件下,构建了以豆蚜Aphis craccivora为食物的大草蛉Chrysopa pallens实验种群生命表,明确其种群发育情况,并研究了饥饿对大草蛉食物利用率的影响.结果 表明,大草蛉卵、1龄、2龄、3龄幼虫和蛹的发育历期分别为3.03、3.10、3.39、4.43和12.52 d,雌成虫平均寿命为29.38 d,个体繁殖力为325.76±16.06粒.内禀增长率(r)、周限增长率(λ)、净增殖率(R0)和世代平均周期(T)分别为0.1197 d-1、1.1076 d-1、68.41粒/个体和41.36 d.在饥饿胁迫下,大草蛉3龄幼虫的食物利用率显著高于2龄幼虫,且随着饥饿程度的增加,2龄、3龄幼虫的食物利用率也逐渐增大.说明在25℃时,以豆蚜为食物的大草蛉个体发育和种群增长情况较好,为以豆蚜作为替代食物饲养大草蛉以及大草蛉作为天敌昆虫防控豆蚜提供了理论基础;饥饿对大草蛉的食物利用率的研究为明确天敌昆虫在田间应用时面临食物短缺问题时的取食状况提供了基础数据.     

不同宽度林带对国道两侧农田水稻叶片和糙米中重金属含量的影响

以205国道淮安段具有5 m和20 m宽林带的路段为研究区域,对国道东西两侧200 m范围内农田水稻(Oryza sativa L.)叶片和糙米中Al、Fe、Cu、Zn、Cd、Cr、Ni和Pb含量及其与路侧距离的相关性进行了分析.结果表明:具5 m宽林带路段两侧稻叶和糙米中大多数重金属元素的含量呈现随路侧距离增加而减少的趋势,且峰值多出现在距路侧5～10m或20 m附近;其中,东侧稻叶中Cu、Cr和Ni含量及糙米中Al、Fe、Cu、Zn和Ni含量以及西侧稻叶中Cu和Pb含量及糙米中Cd和Pb含量与路侧距离呈显著或极显著负相关.具20m宽林带路段两侧稻叶和糙米中大多数重金属元素的含量并没有呈现随路侧距离增加而减少的趋势,且峰值多出现在距路侧20 m以外;只有东侧稻叶中Cr和Ni含量及糙米中Fe和Ni含量以及西侧糙米中Al和Cu含量与路侧距离呈显著或极显著负相关.具5m宽林带路段两侧稻叶和糙米中的重金属含量分布特征与无林带路段十分相似,而具20m宽林带路段两侧稻叶和糙米中的重金属含量较低,说明20 m宽林带对公路大气污染物有较明显的阻滞作用.根据研究结果,建议在公路两侧10～20 m范围内设置乔灌草结构模式的防护林带,并适当提高防护林中灌木的比例,保持乔木疏密适度.     

Effects of management and structural connectivity on the plant communities of organic vegetable field margins in South Korea

Field margins are an important component of the agri-environment as they contribute to maintaining ecosystem functions and protecting biodiversity. Field margin structure, landscape attributes, and management practices have been examined as determinants of plant species diversity and composition for mainly cereal field margins; however, relatively little is known about their influence on vegetable field margins. We selected three types of field margins (each n = 4; non-managed connected to forests, non-managed isolated, and isolated and managed margins with mowing and organic herbicide) adjacent to organic vegetable crop fields and recorded the species richness and abundance of all vascular plants. The effects of structural connectivity, weed control management, and margin width on the community composition, species richness, and diversity were examined using multivariate statistical techniques. Plant community composition was clearly explained by structural connectivity between field margin and forest, as well as by weed control management. In contrast, species richness of functional guilds was influenced by connectivity and margin width, but not by weed control management. All communities had similar numbers of summer and fall blooming nectar- and pollen-producing plants, an important source of pollination services. In addition, each community of field margin types, despite different species composition, had similar levels of Shannon diversity and evenness. Our results suggest that habitat arrangement is important for determining community composition in field margins. Management practices may be important in determining dominance patterns of individual species. A combination of various margin types and widths may be beneficial for biodiversity conservation and ecosystem services.     

Limited Effects of Large‐Scale Riparian Restoration on Seed Banks in Agriculture

I examined the effect of riparian forest restoration on plant abundance and diversity, including weed species, on agricultural lands along the Sacramento River in California (United States). Riparian forest restoration on the Sacramento River is occurring on a large‐scale, with a goal of restoring approximately 80,000 ha over 160 km of the river. In multiuse habitats, such as the Sacramento River, effects of adjoining habitat types and movement of species across these habitats can have important management implications in terms of landscape‐scale patterns of species distributions. Increased numbers of pest animals and weeds on agricultural lands associated with restored habitats could have negative economic impacts, and in turn affect support for restoration of natural areas. In order to determine the distribution and abundance of weeds associated with large‐scale restoration, I collected seed bank soil samples on orchards between 0 and 5.6 km from adjacent restored riparian, remnant riparian, and agricultural habitats. I determined the abundance, species richness, and dispersal mode of plant species in the seed bank and analyzed these variables in terms of adjacent habitat type and age of restored habitat. I found that agricultural weed species had higher densities at the edge of restored riparian habitat and that native plants had higher densities adjacent to remnant riparian habitat. Weed seed abundance increased significantly on walnut farms adjacent to restored habitat with time since restored. I supply strong empirical evidence that large areas of natural and restored habitats do not lead to a greater penetration of weed species into agricultural areas, but rather that weed penetration is both temporally and spatially limited.     

Assessment of livestock grazing pressure in and around the elephant corridors in Mudumalai Wildlife Sanctuary, south India

Mudumalai Wildlife Sanctuary in southern India plays an important role in biodiversity conservation, especially of large mammals, by offering habitat contiguity of about 3300 km² with three other protected areas in the region, namely Nagarahole and Bandipur National Parks and Wynaad Wildlife Sanctuary through forest corridors between the Western Ghats and Eastern Ghats forests. The habitat linkage is crucial for large ranging animals such as elephants, which use these forest corridors for migration. Livestock grazing, a major biotic interference in forest corridors, originates from seven settlements of the Masinagudi group of villages on the eastern and the southeastern fringes of the sanctuary. Construction of a series of hydroelectric power stations, numbering about three at Singara, Marvakandy (Masinagudi) and Moyar, around the Masinagudi villages caused a rapid growth in human population (143% between 1961 and 1991), particularly the landless labourers and livestock. Free grazing by about 15 000–17 000 resident as well as migratory livestock every year in and around the forest corridors, coupled with removal of cattle dung from the forest floor, have adversely affected the forest regeneration and helped proliferation of weed species such as Lantana camara, Casia tora, C. occidentalis, Opuntia dillenii, and Ageratum conyzoides. The annual fodder production from the corridor forest could meet the demand of about two-thirds of the resident population, while the crop residues from the marginal agriculture could not support the remaining one-third livestock population. In view of such a situation, measures have been suggested to reduce livestock population and implement the ecodevelopment packages in order to ensure the corridor connectivity for the long-term conservation of the elephant population.     

Questioning the relevance of shifting cultivation to Neolithic farming in the loess belt of Europe: evidence from the Hambach Forest experiment

Despite widespread criticism, the shifting cultivation model continues to inform discussion of Neolithic farming in Europe, beginning with early Neolithic (Linearbandkeramik or LBK) communities concentrated in the loess belt of western-central Europe. Hundreds of LBK and later Neolithic sites have been excavated in this region and many of them sampled for charred plant remains. Archaeobotanical data on the weed floras harvested with crops provide the most direct archaeological evidence of crop husbandry practices, including the permanence of crop fields, but have played a limited role in the debate over shifting cultivation. The Hambach Forest experiment, conducted in the 1970s-80s near Cologne, Germany, provides valuable comparative data on the weed floras growing in newly cleared cultivation plots in an area of longlived mixed oak woodland on loess-based soil. Correspondence analysis of the Hambach weed survey data suggests that weed floras of fields managed under a shifting cultivation regime would be rich in perennial species, including woodland perennials. Comparison of these results with Neolithic weed assemblages from the loess belt of western-central Europe strongly suggests that Neolithic crop fields were not recently cleared of woodland vegetation but were long-established. Received September 5, 2001 / Accepted February 26, 2002     

Searching behaviour of the sevenspotted ladybird, Coccinella septempunctata– effects of plant-plant odour interaction

In the present study the main aim was to investigate the odour mechanisms affecting habitat preferences of Coccinella septempunctata (L.). In a field study, the frequency of adult C. septempunctata was higher in barley plots containing high densities of the common weeds Cirsium arvense (L.) Scop. and Elytrigia repens (L.) Nevski. than in control plots with only barley. In olfactometer experiments in the laboratory, adult C. septempunctata showed a significantly more positive response to mixed odours of barley and each of the two weeds than to barley alone. Ladybirds responded differently to barley plants that were previously exposed to volatiles from the two weeds. The E. repens -exposed barley plant lost its attractivity while the C. arvense -exposed barley plants maintained attractivity. As no aphids or pollen resources were present in the plots during the experiment, the results show that C. septempunctata responds to the botanical characteristics of the habitat even if no food resources are available. These results strongly suggest that olfactory cues and plant-plant communication from diversified plant stands can be important mechanisms in predator attraction to sites with a complex botanical diversity.