粽管巢蛛和拟水狼蛛对稻纵卷叶螟和稻褐飞虱捕食作用研究

应用二次正交旋转组合设计方法建立粽管巢蛛和拟水狼蛛对稻纵卷叶螟和稻褐飞虱捕食作用的数学模型。结果表明,粽管巢蛛是稻纵卷叶螟的重要天敌,粽管巢蛛和拟水狼蛛均是稻褐飞虱的重要天敌。当稻褐飞虱密度较高时,随着蜘蛛密度的增加,由于蜘蛛之间的干扰作用,导致稻褐飞虱被捕食量下降。     

蜘蛛对稻纵卷叶螟和白背飞虱的选择捕食作用

讨论蜘蛛的主要种群拟水狼蛛、食虫瘤胸蛛、粽管巢蛛对稻纵卷叶螟、白背飞虱的选择捕食特性。由结果可见：猎物被捕食量与参试种群编码值（密度）的数量关系可由二次多项式模型技术。当取每科水稻上有稻纵卷叶螟５头,白背飞虱１０头,拟水狼蛛２头,粽管巢蛛２头,食虫瘤胸蛛２头时,蜘蛛种群对白背飞虱有较大的选择捕食比率。     

稻田主要捕食性天敌的栖境生态位与捕食作用分析

本文进行了稻田捕食性天敌与稻飞虱的栖境生态位调查,并应用正交试验设计、添加试验法和排除试验法研究了?物种的栖境生态位与各天敌捕食作用的关系,结果表明：在5种灭敌与2种害虫共存系统中,天敌对褐飞虱Nilaparvata lugens Stal捕食量的正主效应大小依次为： 粽管巢蛛 Clubiona aponicola、青翅蚁形隐翅虫Paederus fuscipes、前齿肖蛸Tetragnatha praedonia、食虫沟瘤蛛 Ummeliata insecticeps,拟水狼蛛Pirata subpiraticus的负主效应值最大(随狼蛛密度增大捕食量下降);对稻纵卷叶螟Cnaphlocrcis medinalis Guenee捕食量正主效应大小依次为： 粽管巢蛛、肖蛸、青翅蚁形隐翊虫。多物种共存系统中,狼蛛、微蛛、跳蛛主要捕食飞虱;肖蛸主要捕食稻纵卷叶螟;管巢蛛对两种害虫均具有较好的控制作用。这与各物种的生态位宽度值相一致。当飞虱密度在每穴10一30头时,多物种共存系统优良的生物序是拟水狼蛛、食虫瘤胸蛛、青翅蚁形隐翅虫各为l头,棕管巢蛛2头,此时天敌的控制作用最大。添加法和排除法试验结果表明在具-定数量的多物种共存系统中,再增加天敌密度不一定能增加猎物的被捕食数,其直接的生物学原因是种间种内干扰(包括种间种内残杀)     

用ELISA方法研究稻田节肢动物的食物关系

应用酶联免疫吸附试验双抗体夹心法,研究了稻田节肢动物,包括19种捕食性天敌、4种主要水稻害虫及1种中性昆虫之间的食物关系。在检测的19种捕食者中,有15种捕食了白背飞虱,11种捕食了褐飞虱。其中食虫沟瘤蛛、拟水狼蛛、八斑鞘蛛、粽管巢蛛、四斑锯螯蛛和拟环纹豹蛛对两种稻飞虱的捕食阳性率较高。有7种捕食了稻纵卷叶螟幼虫,其中粽管巢蛛、褶管巢蛛、拟环纹豹蛛、青翅蚁形隐翅虫和印度细颈步甲的捕食阳性率较高。拟环纹豹蛛、浙江豹蛛和拟水狼蛛对稻蝗若虫有较高的阳性率。13种捕食者捕食了摇蚊,摇蚊作为替代或补充猎物,对稻田捕食性节肢动物亚群落的重建和发展具有重要意义。在实验检测的基础上,构建了被检测节肢动物猎物与捕食者间的食物关系图。     

稻田多种蜘蛛对褐飞虱(Nilaparvata lugens)捕食量的数学模型及关联度研究

应用灰色系统理论研究了4种蜘蛛(拟水狼蛛、食虫瘤胸蛛、粽管巢蛛、菱头跳蛛)与褐飞虱共存系统捕食量的数学模型.对此模型的分析可以了解各天敌不同数量或者密度与褐飞虱不同密度组合下对褐飞虱捕食量的影响.应用该模型还可以预测相应时期的捕食量大小,所得预测值与实际值几乎一致.同时利用关联度来分析了系统中对褐飞虱捕食量影响最大的因素以及各蜘蛛与褐飞虱捕食量关联程度的大小.     

三种蜘蛛两种害虫共存系统水稻损失率数学模型探讨

本文应用二次回归旋转组合设计研究了三种蜘蛛(拟水狼蛛、食虫瘤胸蛛、粽管巢蛛)两种害虫(稻纵卷叶螟幼虫、褐稻虱若虫)共存系统水稻损失率的数学模型。初步的结果分析表明共存系统中天敌通过捕食害虫能明显地减轻水稻损失;在供试的密度范围内,褐稻虱自身密度每增加1倍,水稻损失率大约增加6％左右;稻纵卷叶螟幼虫密度的增加对水稻损失有加重趋势,但损失率的增量较小。     

稻田多种蜂蛛对褐飞虱（Nilaparvata lugens）捕食量的数学模型及关联度研究

应用灰色系统理论研究了4种蜘蛛（拟水狼蛛、粽管巢蛛、菱头跳蛛）与褐飞虱共存系统捕食量的数学模型,对此模型的分析可以了解各天敌不同数量或者密度与褐飞虱不同密度组合下对褐飞虱捕食量的影响,应用该模型还可以预测相应时期的捕食量大小,所得预测值与实际值几乎一致,同时利用关联度来分析了系统中对褐飞虱捕食量影响最大的因素以及各蜘蛛与褐飞虱捕食量关联程度的大小。     

用ElISA研究稻田节肢类捕食者对稻飞虱的捕食作用

应用酶联免疫吸附试验(ELlSA)来研究捕食作用能较准确地评价捕食性天敌对害虫的控制作用。ELlSA检测表明,不同种类的捕食性天敌对稻飞虱的捕食作用有较大差别,其中以优势种食虫沟瘤蛛和拟水狼蛛的捕食作用最大,阳性反应率与稻飞虱的种群密度有一定的相关关系,但在稻飞虱密度较低的情况下也表现出较高的阳性反应率。     

稻田主要天敌对害虫的捕食作用

应用二次正交旋转组合设计方法建立3种天敌、2种害虫共存情况下白背飞虱被捕食数量与5个因素相互关系的数学模型。结果表明,3种天敌对白背飞虱被捕食量影响的大小排序为拟水狼蛛>青翅蚁形隐虫>食虫沟瘤蛛,食虫沟瘤蛛与拟水狼蛛、拟水狼蛛与青翅蚁形隐翅虫有负交互作用。     

特征根回归法在稻田捕食性天敌捕食量分析中的应用

应用特征根回归法建立和拟水狼蛛（Pirta subpiraticus),食虫瘤胸蛛（Oedothorax insecticeps),粽管巢蛛（Clubiona japonicola)和菱头跳蛛（Bianor hotingchiehi)4种蜘蛛与竭飞虱（Nlaparvata lugens)共存系统捕食量的特征根回归模型：y=6.6600 6.3399(-0.0138X1^* 0.0895X2^* 0.0078X3^*-0.1067X4^* 0.6742X5^*)。以此模型对蜘蛛捕食量进行了模拟或预测分析,并同LS回归方法进行了比较。结果表明,特征根回归法可用于蜘蛛对褐飞虱捕食量的定量分析,比LS回归方法提高精度10％。     

桔园内多种天敌对桔全爪螨的控制作用

本文应用二次回归旋转组合实验设计统计方法,对桔园内主要天敌食螨瓢虫(Stethorus che-ngi)、长须螨(Agistemus exsertus citri)、尼氏钝绥螨(Amblyseius nichols)和普通钝绥螨(Amb-lyseius vulgaris)对桔全爪螨(Panongchus citri)的控制作用,以及天敌与天敌之间、天敌与害螨之间的相互作用进行了研究。得出了这4种天敌对桔全爪螨的捕食量模型。并对模型进行主效分析,表明桔全爪螨自身密度的大小对天敌的总捕食量影响最大。在这4种天敌中对总的捕食量影响最大的是食螨瓢虫,其次为长须螨,尼氏钝绥螨再次之,普通钝绥螨的影响最小。对各天敌间交互作用的分析表明,天敌个体大、活动能力强、捕食量大,他们的种内种间干扰程度也大,特别是食螨瓢虫种内种间干扰十分明显。其次为长须螨,而尼氏钝绥螨和普通钝绥螨的种内种间干扰较弱,在密度较低时,他们还表现出相互促进的作用。最后本文还讨论了这4种天敌能有效地控制桔全爪螨的最大密度,以及在该密度下各种天敌密度的最佳组合。     

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.     

Intraguild predation reduces redundancy of predator species in multiple predator assemblage

1. Interference between predator species frequently decreases predation rates, lowering the risk of predation for shared prey. However, such interference can also occur between conspecific predators. 2. Therefore, to understand the importance of predator biodiversity and the degree that predator species can be considered functionally interchangeable, we determined the degree of additivity and redundancy of predators in multiple- and single-species combinations. 3. We show that interference between two invasive species of predatory crabs, Carcinus maenas and Hemigrapsus sanguineus, reduced the risk of predation for shared amphipod prey, and had redundant per capita effects in most multiple- and single-species predator combinations. 4. However, when predator combinations with the potential for intraguild predation were examined, predator interference increased and predator redundancy decreased. 5. Our study indicates that trophic structure is important in determining how the effects of predator species combine and demonstrates the utility of determining the redundancy, as well as the additivity, of multiple predator species.     

Additive effects of predator diversity on pest control caused by few interactions among predator species

1. Studies of the impact of predator diversity on biological pest control have shown idiosyncratic results. This is often assumed to be as a result of differences among systems in the importance of predator–predator interactions such as facilitation and intraguild predation. The frequency of such interactions may be altered by prey availability and structural complexity. A direct assessment of interactions among predators is needed for a better understanding of the mechanisms affecting prey abundance by complex predator communities. 2. In a field cage experiment, the effect of increased predator diversity (single species vs. three‐species assemblage) and the presence of weeds (providing structural complexity) on the biological control of cereal aphids were tested and the mechanisms involved were investigated using molecular gut content analysis. 3. The impact of the three‐predator species assemblages of aphid populations was found to be similar to those of the single‐predator species treatments, and the presence or absence of weeds did not alter the patterns observed. This suggests that both predator facilitation and intraguild predation were absent or weak in this system, or that these interactions had counteracting effects on prey suppression. Molecular gut content analysis of predators provided little evidence for the latter hypothesis: predator facilitation was not detected and intraguild predation occurred at a low frequency. 4. The present study suggests additive effects of predators and, therefore, that predator diversity per se neither strengthens nor weakens the biological control of aphids in this system.     

Disentangling the effects of predator hunting mode and habitat domain on the top-down control of insect herbivores

1.?Polyphagous predatory invertebrates play a key role in the top-down control of insect herbivores. However, predicting predation risk for herbivores is not a simple function of predator species richness. Predation risk may be reduced or enhanced depending on the functional characteristics predator species. We predict that where predator species spatially overlap this will reduce predation risk for herbivores by allowing negative inter-specific interaction between predators to occur. Where increased predation risk occurs, we also predict that this will have a cascading effect through the food chain reducing plant growth. 2.?We used a substitutive replicated block design to identify the effect of similarity and dissimilarity in predator hunting mode (e.g. 'sit and wait', 'sit and pursue', and 'active') and habitat domain (e.g. canopy or ground) on the top-down control of planthoppers in grasslands. Predators included within the mesocosms were randomly selected from a pool of 17 local species. 3.?Predation risk was reduced where predators shared the same habitat domain, independent of whether they shared hunting modes. Where predators shared the same habitat domains, there was some evidence that this had a cascading negative effect on the re-growth of grass biomass. Where predator habitat domains did not overlap, there were substitutable effects on predation risk to planthoppers. Predation risk for planthoppers was affected by taxonomic identity of predator species, i.e. whether they were beetles, spiders or true bugs. 4.?Our results indicated that in multi-predator systems, the risk of predation is typically reduced. Consideration of functional characteristics of individual species, in particular aspects of habitat domain and hunting mode, are crucial in predicting the effects of multi-predator systems on the top-down control of herbivores.     

Dietary specialization is conditionally associated with increased ant predation risk in a temperate forest caterpillar community

The enemy‐free space hypothesis (EFSH) contends that generalist predators select for dietary specialization in insect herbivores. At a community level, the EFSH predicts that dietary specialization reduces predation risk, and this pattern has been found in several studies addressing the impact of individual predator taxa or guilds. However, predation at a community level is also subject to combinatorial effects of multiple‐predator types, raising the question of how so‐called multiple‐predator effects relate to dietary specialization in insect herbivores. Here, we test the EFSH with a field experiment quantifying ant predation risk to insect herbivores (caterpillars) with and without the combined predation effects of birds. Assessing a community of 20 caterpillar species, we use model selection in a phylogenetic comparative framework to identify the caterpillar traits that best predict the risk of ant predation. A caterpillar species' abundance, dietary specialization, and behavioral defenses were important predictors of its ant predation risk. Abundant caterpillar species had increased risk of ant predation irrespective of bird predation. Caterpillar species with broad diet breadth and behavioral responsiveness to attack had reduced ant predation risk, but these ant effects only occurred when birds also had access to the caterpillar community. These findings suggest that ant predation of caterpillar species is density‐ or frequency‐dependent, that ants and birds may impose countervailing selection on dietary specialization within the same herbivore community, and that contingent effects of multiple predators may generate behaviorally mediated life‐history trade‐offs associated with herbivore diet breadth.     

The relationship between predator density, community composition, and field predation of Colorado potato beetle eggs

Conservation biological control programs seek to increase natural enemy densities through the adoption of more benign farming practices, under the assumption that higher predator densities will lead to more effective pest suppression. However, predator–predator interference may lead to diminishing returns in improved pest control as predator densities increase. We examined the relationship between predator density and predation rates on Colorado potato beetle eggs in production potato fields. These potato fields naturally spanned a 10-fold range in predator density, due to differences in management practices. Periodically through the growing season we simultaneously measured predator densities and subjected sentinel eggs masses to predation, allowing us to correlate predator density and egg predation for each field on each sample date. Egg predation rates were significantly positively correlated with total predator densities, a correlation that was not improved when predator densities were scaled to reflect differences in feeding rates on potato beetle eggs of the constituent predator taxa. There was no correlation between per-capita egg predation rates and predator density, and so no evidence that predator interference increased with increasing predator density. We divided predators into six dominant taxa—dwarf spiders, crab spiders, minute pirate bugs, big-eyed bugs, damsel bugs, and Lygus bugs (together constituting 93% of all predators collected), and a seventh group, “other predators” that included all other, less common, taxa—and examined correlations between all predator combinations and egg predation rates. The highest correlation was between combined densities of the six most common predator taxa, excluding only the “other predators” grouping. This suggests that predators may be largely equivalent in their impact on Colorado potato beetle eggs, and that field scouts might be able to ignore uncommon predator taxa when sampling for natural enemies.     

Interspecific infanticide deters predators

It is well known that young, small predator stages are vulnerable to predation by conspecifics, intra-guild competitors or hyperpredators. It is less known that prey can also kill vulnerable predator stages that present no danger to the prey. Since adult predators are expected to avoid places where their offspring would run a high predation risk, this opens the way for potential prey to deter dangerous predator stages by killing vulnerable predator stages. We present an example of such a complex predator–prey interaction. We show that (1) the vulnerable stage of an omnivorous arthropod prey discriminates between eggs of a harmless predator species and eggs of a dangerous species, killing more eggs of the latter; (2) prey suffer a minor predation risk from newly hatched predators; (3) adult predators avoid ovipositing near killed predator eggs, and (4) vulnerable prey near killed predator eggs experience an almost fourfold reduction of predation. Hence, by attacking the vulnerable stage of their predator, prey deter adult predators and thus reduce their own predation risk. This provides a novel explanation for the killing of vulnerable stages of predators by prey and adds a new dimension to anti-predator behaviour.     

Optimal Xylocoris flavipes (Reuter) (Hemiptera: Anthocoridae) density and time of introduction for suppression of bruchid progeny in stored legumes

The influences of both predator density and elapsed time between initial infestation and introduction of predators were determined for suppression of bruchids infesting stored grain legumes by Xylocoris flavipes (Reuter) (Hemiptera: Anthocoridae). Predator density treatments consisted of zero, one, two, three, or five male:female pairs of adult X. flavipes added to experimental arenas 0, 24, or 120 h after bruchid introduction. Suppression of Acanthoscelides obtectus approached eradication with all predator treatments. For all other bruchid species evaluated (Callosobruchus analis, C. chinensis, C. maculatus, and Zabrotes subfasciatus), the most effective predator density and addition time (five predator pairs at 0 h) resulted in an approximately 50% reduction of emerging F1 bruchids compared with progeny produced in arenas without predators. The predator addition time of 0 h, when predators were added to experimental arenas simultaneously with the pest species, was determined to be the universally most efficacious treatment time. Predator density above one pair but lower than five pairs was less influential overall when X. flavipes was added 24 or 120 h after initial bruchid infestation; however, maximum suppression was achieved at approximately two predator pairs and not significantly improved on with increased predator density. Our results indicate that the most effective biological control of pest bruchids would occur when X. flavipes is added as soon as possible after legumes are stored.     

稻田穗期主要捕食性天敌对两种盲蝽集团内捕食的初步研究

【目的】集团内捕食是影响农业系统广食性天敌对靶标害虫控制作用的重要因素,全面揭示稻田广食性天敌对稻飞虱重要天敌黑肩绿盲蝽Cyrtorhinus lividipennis Reuter和中华淡翅盲蝽Tytthus chinensis(St?l)(半翅目:盲蝽科)的集团内捕食作用有助于更好地保护利用天敌。【方法】建立以两种盲蝽为猎物对象的种特异性二重定量PCR系统,检测比较不同抗性品种穗期田间主要捕食者对两种盲蝽的集团内捕食作用。【结果】(1)本研究建立的二重定量PCR具有的物种专化性,两种检测靶标灵敏度高且相似,可用于田间捕食者猎物分析;(2)感虫水稻品种上捕食者对盲蝽的捕食强度高于抗性水稻品种;不同种类捕食者对盲蝽的集团内捕食强度有显著差异;捕食者对黑肩绿盲蝽集团内捕食强度显著高于中华淡翅盲蝽。【结论】捕食性盲蝽在稻田生态系统遭遇集团内捕食,其集团内捕食强度与水稻品种抗性、捕食者种类和猎物丰富度有关。