小麦-油菜邻作对麦田主要害虫和天敌的影响

应用昆虫群落生态学的群落特性分析方法,于2008年和2009年在河北省邯郸市调查了小麦与油菜邻作对麦田蚜虫及主要天敌群落的构成、丰富度和稳定性的影响.结果表明：小麦与油菜田间昆虫群落的组成相似,主要田间害虫为蚜虫,其捕食性天敌包括瓢虫类、草蛉类、蜘蛛类和食蚜蝇,寄生性天敌为蚜茧蜂;两年间田间昆虫群落的组成有一定的变化,但均表现为邻近油菜的麦田蚜虫丰富度最低,捕食性天敌和寄生性天敌的丰富度最高;邻近油菜的麦田昆虫群落、麦蚜亚群落、捕食性天敌亚群落的稳定性高,远离油菜的稳定性低.该模式可以有效保护和利用天敌,增强田间自然天敌对害虫的控制能力.     

植被边界带对相邻麦田地表步甲和蜘蛛分布及蚜虫发生的影响

通过管理半自然生境提高农田中天敌多样性及农田害虫的生物控制效率是当前生态农业研究的基本问题之一。为探讨不同类型半自然植被边界带对相邻麦田地表天敌的发生以及对小麦蚜虫生物控制潜力的影响,在北京顺义区赵全营镇采用陷阱法调查了不同类型植被边界带（人工林地、人工种植草带、自然演替草带）相邻的小麦田中,距离边界0,15 m和30 m处步甲和蜘蛛两类重要地表天敌的多度分布及小麦田蚜虫发生情况,同时分析了边界带植被群落结构对步甲和蜘蛛群落分布的影响。结果表明：人工林地相邻的小麦田中维持了显著较高的步甲、蜘蛛和蚜虫发生密度;不同类型植被边界带相邻小麦田中步甲和蜘蛛群落组成显著不同,植被边界带宽度以及乔木层盖度是影响相邻麦田步甲和蜘蛛群落分布的主要因子;距离植被边界带不同取样界面处,不同迁移方向的步甲和蜘蛛的活动密度无显著性差异;与林地相邻的麦田中,蜘蛛活动密度从农田边界向农田内部处依次降低,与人工种植草带以及自然演替草带相邻的麦田中,农田边界处蜘蛛的活动密度显著高于农田内部。研究显示,半自然植被边界带与麦田交界处维持了较高的蜘蛛活动密度,并具有向农田内部扩散的趋势,然而,并非高天敌密度就意味着低害虫发生率,深入研究天敌群落与害虫发生关系及其影响因素是未来天敌保护和害虫生物防治的重要方面。同时,因为不同类型植被边界带维持的天敌群落具有高度异质性,未来的研究需要充分考虑不同类型植被边界带对天敌维持的作用,以及不同类型生境界面地表天敌的活动规律。     

麦田天敌种群动态及主要天敌对麦蚜捕食效能的研究

查明麦田害虫天敌有98种,其中捕食性天敌80种,寄生性天敌18种,对天敌种群动态作了系统观察,分析了影响天敌种群数量的环境因素,对大灰食蚜蝇,黑带食蚜蝇,七星瓢虫捕食麦蚜效能进行了探讨。     

夏大豆田主要害虫及天敌生态位研究

研究了7—8月份夏大豆田主要食叶性害虫及其天敌的生态位宽度和生态位重叠度。分析了各昆虫种间的竞争动态,害虫与其天敌在时间上的同步性和空间上的同域性均较强,为保护利用自然天敌控制夏大豆害虫提供了科学依据。     

北方富含天敌的功能植物的发现与应用

蛇床Cnidium monnieri(L.)Cuss.是我国大部分地区均有分布的一种具有重要药用经济价值的植物。我们于2012年6月最先在北方发现蛇床上富含瓢虫、食蚜蝇等天敌昆虫,具备功能植物的基本特征。进一步研究发现,蛇床可使天敌昆虫提前迁入,在麦田害虫发生之前助增天敌瓢虫迁入麦田控害,且作为小麦、玉米之间的廊道以及它们收获后天敌的保育场所,从而周年实现对害虫的生态调控。蛇床同时具有种植管理轻简,适生性强,种子不扩散到农田内部成为杂草,且具观赏功能等可应用特点。因此,通过作物周边种植蛇床,作为害虫生态调控的一种新途径,可为农民实现增收、减少化学农药的使用、改善生态环境,具有重要的经济价值、生态价值和社会价值。     

麦田蜘蛛调查研究初报

通过大田系统调查,发现青州地区麦田蜘蛛有11科,24种。蛛量以狼蛛科最大,占总蛛量的30.5%;漏斗蛛科次之,占20.6%;蟹蛛科第三,占19.5%。其优势主要集中在麦株下部,数量达总数的95%以上,但不同空间的优势类群随小麦生育期不同发生相应变化。蜘蛛与麦田红蜘蛛、粘虫、麦蚜的发生呈“水涨船高,亦步亦趋之势”,对害虫的控制起到明显作用,是值得研究和利用的麦田害虫重要天敌类群之一。     

麦蚜与龟纹瓢虫在麦田的空间格局分析

【目的】为保护麦田天敌并合理利用天敌对麦蚜进行控制。【方法】通过田间网格式取样调查,应用生态位和地统计学方法研究了麦田中麦蚜及其主要天敌龟纹瓢虫Proplaea japonica的时空分布格局。【结果】麦蚜及瓢虫时间序列上的种群动态分析显示,麦田中龟纹瓢虫发生期比麦蚜滞后,麦蚜与龟纹瓢虫的种群数量动态趋势相似,种群相关系数为0.930,表明龟纹瓢虫与麦蚜种群呈明显的跟随关系。在空间上,麦蚜和龟纹瓢虫两者的生态位重叠度随着麦蚜的发生量增多而增高,最高达0.52。麦蚜与龟纹瓢虫的空间格局在时间序列上,随着种群数量改变而变化。在低种群密度下,麦蚜的半变异函数为线性模型,呈随机分布;在高密度下,麦蚜和龟纹瓢虫的的半变异函数均为指数模型,呈聚集分布。Block Kriging空间插值分析,得到二维空间插值模拟图,较好反映了麦蚜和龟纹瓢虫种群在麦田的时空分布。【结论】麦田生态系统中麦蚜与其天敌——龟纹瓢虫在时空分布上具有较强的相似性。同时研究结果提示,评价自然天敌对害虫的控害功能时,要综合分析两者的数量关系和空间分布关系及其控害功能的协同作用,才能提出可靠的防治策略。     

转双抗虫基因741杨节肢动物群落营养结构及生态位变化

转双抗虫基因741杨（简称转基因741杨）节肢动物群落中,基位物种的植食性昆虫丰富度显著降低,但中性节肢动物丰富度却明显增加.高抗和中抗的节肢动物群落中位物种和顶位物种较之对照有所增多.转基因741杨节肢动物群落的害虫功能团,其优势状况,与对照相比有所改变：天敌优势度高于对照,中性节肢动物丰富度增加,并在天敌-害虫的营养链中起着重要的调控作用.鳞翅目害虫的空间生态位宽度最小,其它各功能类群的生态位宽度较大;捕食性和寄生性天敌与鳞翅目害虫的生态位重叠均较小,而与腐生和游逛种类的生态位重叠较大;各类害虫之间、捕食性天敌与寄生性天敌之间亦存在激烈竞争.转基因741杨对寄生性天敌和捕食性天敌在利用时间资源上有正作用.各种功能类群的时-空二维生态位宽度和生态位重叠均不如单维生态位宽度和生态位重叠值大,但抗性株系天敌类群对环境的适应性优于对照.     

新疆麦蚜主要天敌的生态位

利用生态位理论,对新疆塔城、伊犁两地区麦田麦蚜主要天敌类群瓢虫类、食蚜蝇类、斑腹蝇类、蚜茧蜂类和蚜小蜂类的生态位宽度和重叠度进行了计算和分析。瓢虫类在塔城和伊犁小麦田的时间生态位宽度均较长。塔城食蚜蝇类和瓢虫类的时间生态位重叠度最大。伊犁麦田食蚜蝇类空间生态位最宽,瓢虫类时-空生态位宽度最大,斑腹蝇类和瓢虫类时间生态位的重叠度最大,蚜小蜂和斑腹蝇空间生态位以及时-空生态位的重叠度最大。对伊犁大麦田和燕麦田蚜虫的天敌生态位也进行了计算分析。     

棉田生态系统中害虫、天敌群落结构与功能关系的研究

为探讨生物群落结构与功能的关系,有效地开展棉田害虫、天敌的生态调控,作者在系统调查与测定华北棉区８种不同时空类型棉田害虫、天敌群落物种丰富度、总个体数、能流量多样性指数及群落生产力的基础上,分析了各类型棉田害虫、天敌群落结构与功能的关系,总结了如下的一般规律：１）上一营养层（棉株或害虫）的生产力越高,其所支持的下一营养层（害虫或天敌）群落的总个体数和生产力增加;２）害虫群落的物种丰富度与其群落生产     

广聚萤叶甲和豚草卷蛾对广西来宾豚草的联合控制作用

【背景】豚草已成功入侵广西来宾,对当地生物多样性、农业生产和居民健康造成了严重影响。广聚萤叶甲和豚草卷蛾均为豚草的重要专一性天敌,在湖南等地已有效抑制了豚草的扩散蔓延。【方法】为考查2种天敌在广西对豚草的联合控制作用,于2009年5月24日在广西来宾豚草入侵地区同时释放广聚萤叶甲和豚草卷蛾(2种天敌释放密度均为1170头.hm-2)。【结果】至2009年8月29日释放区内豚草植株死亡率达98%以上,且天敌迅速向邻近豚草发生区扩散,2种天敌对扩散区豚草的控制率可达50%～60%。【结论与意义】2种天敌对豚草具有显著的控制效果,建议在广西大面积推广应用。     

梨园芳香植物间作区节肢动物群落时序格局

以沙地梨园间作罗勒、孔雀草、薄荷为处理,自然生草和清耕区为对照,应用最优分割法和模糊聚类法,探讨梨园节肢动物群落、害虫亚群落和天敌亚群落发生的时序格局特征及其相互联系。结果表明:总群落、害虫亚群落以及其优势种个体数时序变化趋势呈偏态分布,而天敌亚群落以及其优势种个体数的呈正态分布,高峰期出现在6月末至7月中旬,比总群落和害虫亚群落个体数发生高峰晚。在梨树年生长周期的主要时段中,芳香植物间作区较自然生草区、清耕区害虫亚群落的发生数量(4月中至8月底)少;而天敌亚群落发生数量(4月底至6月底)多。梨园各间作区节肢动物总群落和害虫亚群落时序最优格局均可划分5个时段:发展初期、发展期、稳定期、波动期和衰退期;天敌亚群落分为3个时段:发展期、稳定期、衰退期。但处理间在发生时段的时间范围、发生数量及组成特征上存在复杂的差异。梨园节肢动物总群落、害虫亚群落、天敌亚群落时序聚类结果不同,预示着处理间节肢动物总群落、害虫亚群落和天敌亚群落在各发生时段上的个体组成、物种丰富度、群落多样性指数、优势度和均匀度指数存在着差异。     

Understanding biodiversity effects on prey in multi-enemy systems

Biodiversity–ecosystem functioning theory would predict that increasing natural enemy richness should enhance prey consumption rate due to functional complementarity of enemy species. However, several studies show that ecological interactions among natural enemies may result in complex effects of enemy diversity on prey consumption. Therefore, the challenge in understanding natural enemy diversity effects is to predict consumption rates of multiple enemies taking into account effects arising from patterns of prey use together with species interactions. Here, we show how complementary and redundant prey use patterns result in additive and saturating effects, respectively, and how ecological interactions such as phenotypic niche shifts, synergy and intraguild predation enlarge the range of outcomes to include null, synergistic and antagonistic effects. This study provides a simple theoretical framework that can be applied to experimental studies to infer the biological mechanisms underlying natural enemy diversity effects on prey.     

不同产地白蜡虫(Ericerus pela Chavannes)产卵期天敌的种类及其群落结构研究

白蜡虫雌虫产卵期是白蜡种虫生产的关键时期,在我国白蜡主产地区,选择有代表性的4个种虫产地,2个白蜡产地和4个虫蜡混产地,调查群落中白蜡虫天敌的物种组成和数量变化,并进行聚类分析和排序,在10个白蜡主产地内,共收集到各种天敌15种,分属于6科11属,各群落的物种组成变化较小,优势种为白蜡虫花翅跳小蜂Microterys ericeri Ishii、中华花翅跳小蜂M.sinicus Jiang、白蜡虫啮小蜂Tetrastichus kodaikanalensis Saraswat、白蜡蚧长角象Anthribus la-jievorus Chao和黑缘红瓢虫Chilocorus rubidus Hope。群落的优势集中指数较小,多样性指数和均匀性指数较高,群落相似性系数最高达97.46%,最低为75.92%。影响群落相似性的主要因子为白蜡产区不同、生态环境差异和优势种天敌的数量变化,根据聚类分析和排序,将10个不同产地白蜡虫天敌群落分为3类;第1类为种虫产地,优势种天敌发生和危害较轻;第2类为白蜡产地,白蜡虫天敌发生和危害极为严重,其种群数量为第1类的3.36倍,第3类虫蜡皆产,其天敌数量介于第1、2类之间,中华花翅跳小蜂种群数量在第1、3类群落中大致相等,第2类发生较较重,白蜡虫天敌的严重危害是造成蜡区不产种虫的主要原因之一。     

Functional benefits of predator species diversity depend on prey identity

Abstract.  1. Determining the functional significance of species diversity in natural enemy assemblages is a key step towards prediction of the likely impact of biodiversity loss on natural pest control processes. While the biological control literature contains examples in which increased natural enemy diversity hinders pest control, other studies have highlighted mechanisms where pest suppression is promoted by increased enemy diversity.
2. This study aimed to test whether increased predator species diversity results in higher rates of predation on two key, but contrasting, insect pest species commonly found in the rice ecosystems of south-east Asia.
3. Glasshouse experiments were undertaken in which four life stages of a planthopper ( Nilaparvata lugens ) and a moth ( Marasmia patnalis ) were caged with single or three-species combinations of generalist predators.
4. Generally, predation rates of the three-species assemblages exceeded expectation when attacking M. patnalis , but not when attacking N. lugens. In addition, a positive effect of increased predator species richness on overall predation rate was found with M. patnalis but not with N. lugens .
5. The results are consistent with theoretical predictions that morphological and behavioural differentiation among prey life stages promotes functional complementarity among predator species. This indicates that emergent species diversity effects in natural enemy assemblages are context dependent; they depend not only on the characteristics of the predators species, but on the identity of the species on which they prey.     

Parasitoids follow herbivorous insects to a novel host plant,generalist predators less so

The ‘enemy‐free space’ hypothesis predicts that herbivorous insects can escape their natural enemies by switching to a novel host plant, with consequences for the evolution of host plant specialisation. However, if natural enemies follow herbivores to their novel host plants, enemy‐free space may only be temporary. We tested this by studying the colonisation of the introduced tree Eucalyptus grandis (Hill) Maiden (Myrtaceae) by insects in Brazil, where various species of herbivores have added eucalyptus to their host plant range, which consists of native myrtaceous species such as guava. Some herbivores, for example, Thyrinteina leucoceraea Ringe (Lepidoptera: Geometridae), cause outbreaks in eucalyptus plantations but not on guava, possibly because eucalyptus offers enemy‐free space. We sampled herbivores (mainly Lepidoptera species) and natural enemies on eucalyptus and guava and assessed parasitism of Lepidoptera larvae on both host plant species during ca. 2 years. Overall, predators were encountered more frequently on guava than on eucalyptus. In contrast, parasitoids were encountered equally and parasitism rates of Lepidoptera larvae were similar on both host plants. This indicates that herbivores may escape some enemies by moving to a novel host plant. However, this escape may be temporary and may vary with time. We argue that studying temporal and spatial patterns of enemy‐free space and the response of natural enemies to host use changes of their herbivorous prey is essential for understanding the role of natural enemies in the evolution of host plant use by herbivorous arthropods.     

Larval parasitoids and pathogens of the fall armyworm in honduran maize

Parasitism by natural enemies of all larval instars of the fall armyworm (FAW),Spodoptera frugiperda, was quantified in 5 Honduran maize fields during the 1984 growing season. Overall, 42.0% of the host larvae were killed by the natural enemy complex. The braconid parasitoidChelonus insularis was the most common natural enemy accounting for 36.8% of the complex and causing 15.5% mortality of FAW larvae. Other important natural enemies included the nematodeHexamermis sp., the tachinidLespesia sp. and the imperfect entomopathogenic fungusNomuraea rileyi. Distinct ranges of larval instars were attacked by several natural enemy species.Chelonus insularis was an important FAW natural enemy at all larval densities observed. Florida Agricultural Experiment Station Journal Series No. 8650 and MIPH-EAP No. 146.     

Natural enemy diversity and pest control: patterns of pest emergence with agricultural intensification

Concern over declining biodiversity and the implications for continued provision of ecosystem services has led, recently, to intense research effort to describe relationships between biodiversity and ecosystem functioning. Here we extend this effort to the relationship between natural enemy species diversity and natural pest control. From simple modelled food‐webs and simulations of natural enemy species loss we derive specific predictions concerning the effect of herbivore life‐history traits, such as life‐cycle type and concealment, on the shape (reflecting diversity effects) and variance (reflecting species composition effects) of the relationship between natural enemy diversity and pest‐control. We show that these predictions are consistent with the emergence of different pest types following intensification of rice production in Asia. We suggest that basic biological insights can help define the structure of ecological processes and allow more accurate predictions of the effect of species loss on the delivery of ecosystem services.     

Reciprocal effects of host plant and natural enemy diversity on herbivore suppression: an empirical study of a model tritrophic system

Many theoretical and empirical studies have shown that species diversity in a trophic level can impact the capture of limited resources in ways that cascade up or down a food web. Only recently, however, have ecologists begun to consider how diversity at multiple trophic levels might act in concert to have opposing or reinforcing effects on resource use. Here, we report the results of an empirical study of a model, tritrophic food web in which we manipulated the diversity of host plant species ( Medicago sativa , Trifolium pratense and Vicia faba ) and natural enemy species ( Harmonia axyridis , Coleomegilla maculata and Nabis sp.) of a widespread herbivorous pest (the pea aphid, Acyrthosiphon pisum ) in laboratory microcosms. We found that increasing natural enemy richness from one to three species increased the proportion of aphids consumed by 0.14. This effect of enemy diversity was due to facilitative interactions and/or a reduction in intraspecific competition in the more diverse assemblages. We also found an independent and additive main effect of host plant richness, with the proportion of aphids consumed by natural enemies decreasing by 0.14 in plant polycultures. A reduction in predator efficiency on a single host plant, Vicia faba , appeared to be responsible for this plant diversity effect. Aphid population sizes were, therefore, simultaneously determined by a top-down effect of natural enemy diversity, and an opposing bottom-up effect of host plant diversity that modified enemy–prey interactions. These results suggest that population sizes in nature, and biotic controls over insect pests, are influenced by species diversity at multiple trophic levels.     

Interactions between resource availability and enemy release in plant invasion

Understanding why some exotic species become invasive is essential to controlling their populations. This review discusses the possibility that two mechanisms of invasion, release from natural enemies and increased resource availability, may interact. When plants invade new continents, they leave many herbivores and pathogens behind. Species most regulated by enemies in their native range have the most potential for enemy release, and enemy regulation may be strongest for high-resource species. High resource availability is associated with low defence investment, high nutritional value, high enemy damage and consequently strong enemy regulation. Therefore, invasive plant species adapted to high resource availability may also gain most from enemy release. Strong release of high-resource species would predict that: (i) both enemy release and resources may underlie plant invasion, leading to potential interactions among control measures; (ii) increases in resource availability due to disturbance or eutrophication may increase the advantage of exotic over native species; (iii) exotic species will tend to have high-resource traits relative to coexisting native species; and (iv) although high-resource plants may experience strong enemy release in ecological time, well-defended low-resource plants may have stronger evolutionary responses to the absence of enemies.