捕食性天敌昆虫控害作用定量评价方法

天敌昆虫田间捕食作用与能力的研究,通常采用田间种群数量调查与分析的方法或笼罩试验来评价其控制作用,但往往与实际情况不符,尤其是对可捕食多种猎物的非专食性天敌,很难说明其在田间对某一特定猎物的控制作用究竟有多大,而分子生物学技术为捕食者-猎物关系评价研究提供了新途径。本文系统介绍了基于种特异性SS-PCR标记技术和TaqMan-MGB实时荧光定量PCR技术的捕食性天敌控害作用定量评价方法及其优缺点,旨在为害虫天敌的种类筛选及其保护利用提供技术指导。     

定量评价天敌昆虫控害功能的稳定同位素方法

天敌在区域性多作物农田景观系统中辗转捕食害虫,对调节和控制害虫种群数量发挥着非常重要的作用。明确天敌昆虫的食物来源和扩散规律是定量评价其控害功能的重要环节。其中,稳定同位素标记方法是追溯生物个体的食物来源和探究其运动规律的重要手段。本文首先介绍该标记方法的基本原理,接着以天敌昆虫龟纹瓢虫Propylea japonica(Thunberg)为例,应用稳定同位素碳标记方法追溯其在棉花和玉米农田景观系统中取食来源与食物比例;最后叙述了稳定同位素方法的应用前景和存在的问题。     

桑粉虱天敌及其利用研究

本文综述了桑粉虱Pealius mori(Takahashi)的寄生性天敌、捕食性天敌以及一些病原性真菌的研究,并探讨了天敌在桑园中应用的潜在可能。     

天敌昆虫对害虫的非直接致死效应

天敌是影响害虫种群动态的重要因素。一般认为天敌对害虫作用的方式,主要是通过直接的捕食或寄生。事实上,天敌还可以通过捕食或寄生过程中产生的"威吓"等非直接致死效应(Non-lethal effects)或胁迫作用(Stress),影响着害虫的生长发育、繁殖。有时这种天敌存在的非直接致死效应对害虫产生的负面影响甚至比天敌对害虫的直接捕食作用还强。显然,评价天敌作用时,除了计算天敌对害虫的直接捕食或寄生的效率,还应考虑天敌存在时对害虫的非直接致死效应。本文基于作者及前人的研究,分别论述了捕食性天敌、寄生性天敌对害虫的非直接致死效应,解析了环境变化对天敌非直接致死效应的影响,探讨了这种非直接致死效应的可能机制,提出了未来的研究发展方向。     

定量评价天敌控害功能的生态能学方法

由于昆虫的能量完全来自于寄主,因此昆虫摄入的能量相当于食物的被取食消耗量。生态能量学方法的基本原理就是捕食性天敌完全依靠捕食猎物(害虫)而获取能量。显然,捕食性天敌摄入的能量就相当于为猎物(害虫)的被捕食消耗量,也即是捕食性天敌摄入量等于猎物(害虫)的被捕食消耗量。由此,可通过研究捕食性天敌和害虫种群的能量动态,定量分析捕食性天敌对害虫的控制作用。本文详细论述了生态能量学方法的基本原理、测算方法,并以棉田捕食性瓢虫类捕食作用为例,介绍了该方法的应用,为定量评价天敌的控害作用提供了一种新方法。     

天敌与转Bt基因抗虫植物的协同控害作用

本文概述了转Bt基因抗虫植物对天敌的影响,特别是天敌与转Bt基因抗虫植物的协同控害作用及其对寄生昆虫抗生发展的影响研究进展。已有的研究表明转Bt基因抗虫植物对天敌并无明显不利的影响,但转Bt基因抗虫植物与天敌的协同控害作用表现出拮抗性、加和性及增效性等多种形式,这种协同作用可能还将影响到害虫对转Bt基因抗虫植物的速率。     

我国烟粉虱主要捕食和寄生性天敌控制能力研究进展

烟粉虱Bemisia tabaci Gennadius是一种广泛分布于世界各地的多食性害虫,对我国多个省市区的农作物和观赏植物造成了严重的危害。化学杀虫剂的大量使用在杀伤天敌的同时使烟粉虱产生了不同程度的抗性,防治越来越困难;相较于化学防治,在不同地区筛选有效的天敌对烟粉虱进行生物防治是对烟粉虱进行有效控制的重要方法。我国报道的捕食性天敌共计26科109种,寄生性天敌共计2科59种。烟粉虱防治过程中由于单一的防治效果不理想,联合多个天敌资源的利用是增加对烟粉虱的生物防治效果的重要手段。本文通过对我国烟粉虱捕食性和寄生性天敌种类系统全面的整理,同时对烟粉虱优势种天敌中的单种或者多种组合利用后对烟粉虱的的控害潜能进行综述,以期为烟粉虱天敌昆虫种类的筛选和实现高效的生物防治提供科学依据。     

农田景观格局对害虫天敌生态控害功能的调控作用

如何提升农田景观的生态服务功能是当前景观生态学和害虫防治学的前沿研究热点.基于区域农田景观格局可显著调节植物-植食性昆虫-天敌之间相互关系的理论基础,本文系统概括总结了农田景观格局及其变化对农田重要天敌多样性与生态控害功能的影响.从不同天敌类群的角度,分析了农田景观格局对捕食性天敌、寄生性天敌、有益微生物及其生态控害功能的调控作用.同时,对优化农田景观作物布局、采取合理的植被生境管理策略进行了展望.本文可为应用植被生境管理提升农田景观中天敌的生态系统服务功能提供参考,进一步促进区域生态农业响应"化学农药减量施用"的战略目标提供理论支撑.     

温室内大花植物对天敌丰度及其控害功能的影响

【目的】大花植物(花粉和花蜜)能否为特殊的寒地温室内各种昆虫的成虫期补充营养,提供食物来源进而影响温室内天敌的控害功能是当前保护地内防控害虫的关键的科学问题之一。【方法】本实验连续两年选择调查了哈尔滨市郊区(寒地,北纬45o)三栋大型玻璃温室的花卉作物栽培引入情况并用粘虫板连续监测了温室内各种节肢动物丰度动态,分析了温室内大花植物栽培比例对各类(种)优势害虫丰度,寄生性天敌及捕食性天敌丰度的影响,探讨了不同天敌类群丰度的关系及害虫多样性与总丰度等关系。【结果】研究表明:较高比例的大花植物栽培整体上能提高害虫的多样性指数,抑制各种害虫种群的暴发,但单一种类的大花植物也会导致较为严重的害虫发生;影响寄生性天敌类群的环境因素与影响捕食性天敌的因素相似,而捕食性天敌(体型较大)对化学农药的喷洒相对更为敏感。【结论】研究结果可为田间生物控害工程的"功能植物"筛选提供信息,为设施农业害虫生物防治提供科学依据。     

橘小实蝇天敌种类及其应用研究进展

橘小实蝇Bactrocera dorsalis(Hendel)是一种广泛分布于亚洲及夏威夷群岛等地的入侵有害生物,对我国的水果和蔬菜造成了严重的影响.橘小实蝇的防治大多使用化学杀虫剂,然而化学杀虫剂的大量使用会导致橘小实蝇产生不同程度的抗性,同时也会杀伤其天敌,防治变得越来越困难;相较于化学防治,在不同地区筛选有效的天敌对橘小实蝇进行生物防治是有效控制的绿色防控措施,契合我国农业农村部大力推进特色优势农作物病虫害绿色防控的工作重点.目前,国内外报道的橘小实蝇寄生性天敌有70余种;捕食性天敌主要为蚂蚁、蠼螋、隐翅虫、螨、蜘蛛、步行虫等;寄生性微生物主要为真菌、细菌、病原线虫、共生菌等;食虫动物主要为鸡、鸟等.橘小实蝇生物防治中,多天敌资源的联合利用可有效增强防治效果.因此,本文系统全面地整理了国内外可查的橘小实蝇天敌种类,以及部分优势单种或多种组合的控害潜能,以期为橘小实蝇天敌种类的筛选和高效的生物防治应用提供参考.     

Bistability induced by generalist natural enemies can reverse pest invasions

Journal of Mathematical Biology - Analytical modeling of predator–prey systems has shown that specialist natural enemies can slow, stop and even reverse pest invasions, assuming that the prey...     

Effect of integrated pest management practices on tomato production and conservation of natural enemies

1 The present study used a crop life table to determine the critical components of production and the key factors of loss in tomato, and three treatments to identify the integrated pest management (IPM) benefits on the reduction of yield losses and the conservation of natural enemies. 2 The relative IPM benefits were compared using calendar‐based pesticide applications, IPM and control (no pesticide). A total of 1248 tomato plants were allotted to treatments with four replicates of 104 plants, each in a random block design. The densities of vectors, leaf miners, fruit borers, predators and parasitoids were compared. 3 Fruit was the critical component of production, experiencing the greatest losses, followed by flower and plant in the vegetative phase. The key causes of loss of production were tospoviruses, Erwinia carotovora, Alternaria solani, Phytophthora infestans, Neoleucinodes elegantalis and blossom‐end rot. 4 No significant differences in yield were detected between the calendar‐based and IPM systems. In the control, the yield was lower than the yield in treatments with pesticides due to losses from fungal diseases and viruses. IPM more efficiently controlled pests than the calendar‐system, reducing the number of parathion‐methyl and abamectin applications by 3.8‐ and 2.9‐fold, respectively. IPM treatment significantly reduced the impact of pesticides on natural enemies. 5 Tomato yield was more affected by biotic and abiotic factors during the reproductive stage. Because fruit was the production component most susceptible to loss, cultivation and IPM programmess should prioritize practices to reduce loss of this component.     

Tandem use of selective insecticides and natural enemies for effective,reduced-risk pest management

Selective chemical insecticides have become the dominant approach for management of recalcitrant and resistant insect pests, and the prospects for use of these chemicals in combination with biocontrol agents are on the rise. These chemical compounds, when used in combination with an effective natural enemy, may provide more comprehensive prophylactic and remedial treatments in the context of an integrated pest management program (IPM) than either approach alone. Many of these compounds have promise for a diversity of applications, including sustainable agriculture, control of urban pests, and invasive species eradication. Unfortunately, there are only a limited number of studies in which the effect of these insecticides on natural enemies has been examined. In this article, we examine the risk of several classes of insecticidal compounds to non-target animals, particularly natural enemies and pollinators, and review the most promising compounds for combined deployment with biological agents.     

Cascade effects of crop species richness on the diversity of pest insects and their natural enemies

Understanding how plant species richness influences the diversity of herbivorous and predatory/parasitic arthropods is central to community ecology.We explore the effects of crop species richness on the diversity of pest insects and their natural enemies.Using data from a four-year experiment with five levels of crop species richness,we found that crop species richness significantly affected the pest species richness,but there were no significant effects on richness of the pests’natural enemies.In contrast,the species richness of pest insects significantly affected their natural enemies.These findings suggest a cascade effect where trophic interactions are strong between adjacent trophic levels,while the interactions between connected but nonadjacent trophic levels are weakened by the intermediate trophic level.High crop species richness resulted in a more stable arthropod community compared with communities in monoculture crops.Our results highlight the complicated cross-trophic interactions and the crucial role of crop diversity in the food webs of agro-ecosystems.     

A review of the natural enemies of beetles in the subtribe Diabroticina (Coleoptera: Chrysomelidae): implications for sustainable pest management

Diabroticina is a speciose subtribe of New World Chrysomelidae (Subfamily Galerucinae: Tribe Luperini) that includes pests such as corn rootworms, cucumber beetles and bean leaf beetles (e.g. Diabrotica, Acalymma, Cerotoma species). The evolution and spread of pesticide resistance, the European invasion of Diabrotica v. virgifera LeConte, and possible development of resistance due to the large-scale deployment of Diabrotica-active Bt maize in North America have generated a sense of urgency in developing biological control options against Diabroticina pests. In the present study, we review available knowledge on biological control options, including 290 publications on natural enemy–Diabroticina associations in the New World. Several natural enemy species or groups appear to be promising candidates for control strategies with different ecological rationales. We propose that future research should pursue: (1) development of inundative biological control products, particularly mass-produced entomopathogenic nematodes and fungi, (2) understanding of specific natural enemies of Diabroticina larvae throughout the Americas and of adults particularly in higher altitudes of Central America or northern South America including potential classical biological control agents against D. v. virgifera; (3) enhancement of natural enemies through cultural practices, i.e., reduced tillage, reduced weed control, cover crops, diversified crop rotations or soil amendments. Research and action must be coordinated to accelerate the exploration of biological control options.     

Insecticides suppress natural enemies and increase pest damage in cabbage

Intensive use of pesticides is common and increasing despite a growing and historically well documented awareness of the costs and hazards. The benefits from pesticides of increased yields from sufficient pest control may be outweighed by developed resistance in pests and killing of beneficial natural enemies. Other negative effects are human health problems and lower prices because of consumers' desire to buy organic products. Few studies have examined these trade-offs in the field. Here, we demonstrate that Nicaraguan cabbage (Brassica spp.) farmers may suffer economically by using insecticides as they get more damage by the main pest diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), at the same time as they spend economic resources on insecticides. Replicated similarly sized cabbage fields cultivated in a standardized manner were either treated with insecticides according common practice or not treated with insecticides over two seasons. Fields treated with insecticides suffered, compared with nontreated fields, equal or, at least in some periods of the seasons, higher diamondback moth pest attacks. These fields also had increased leaf damage on the harvested cabbage heads. Weight and size of the heads were not affected. The farmers received the same price on the local market irrespective of insecticide use. Rates of parasitized diamondback moth were consistently lower in the treated fields. Negative effects of using insecticides against diamondback moth were found for the density of parasitoids and generalist predatory wasps, and tended to affect spiders negatively. The observed increased leaf damages in insecticide-treated fields may be a combined consequence of insecticide resistance in the pest, and of lower predation and parasitization rates from naturally occurring predators that are suppressed by the insecticide applications. The results indicate biological control as a viable and economic alternative pest management strategy, something that may be particularly relevant for the production of cash crops in tropical countries where insecticide use is heavy and possibly increasing.     

Landscape context and management effects on an important insect pest and its natural enemies in almond

Pest control mediated by organisms such as parasitoids is a valuable ecosystem service, particularly with regard to high costs, low effectiveness, and detrimental effects of some agrochemicals. This study examined infestation rates and abundance of pests and their natural enemies in organic and conventional almond orchards in California, differing in landscape context, understory plant cover, and plant species richness. Parasitoids of the commercially most important insect pest of almond, the Navel Orangeworm (NOW) were studied by rearing NOW in collected overwintering nuts. The indirect impact of vertebrate natural enemies of NOW were estimated by counting empty nut shells with feeding marks by wild birds and various mammals, found at the orchard floor. Mean nut infestation by NOW ranged from 0.8% to 37% per orchard and was reduced by parasitism rates, ranging from 0% to 22%, and vertebrate nut damage, ranging from 2% to 96% per orchard. The parasitoids were facilitated by a high proportion of natural habitat surrounding the orchards and high proportion of understory ground cover with vegetation. The vertebrate natural enemies were facilitated by a high proportion of natural habitat surrounding the orchards and plant species richness in the orchard understory. In conclusion, this study shows that pest control mediated by vertebrates and invertebrates promoted by near natural habitats can lower pest pressure by NOW larvae in overwintering almond. In case of the vertebrate nut damage this service might only be temporal and turn into a dis-service during and after harvest because the vertebrates continue to feed on the nuts and may also cause injuries to the trees.     

Integrated pest management programmes increase natural enemies of pear psylla in Central Washington pear orchards

Natural enemies are a potentially important component of successful integrated pest management in Pacific Northwest pear orchards. Producers in Washington have dealt with difficult pear psylla, Cacopsylla pyricola (Förster) (Homoptera: Psyllidae), pressure and waning product effectiveness for decades. This study finds that integrated pest management (IPM) programmes can sustain high levels of natural enemies comparable to organic management. True bugs Deraeocoris brevis (Knight) (Hemiptera: Miridae) and Campylomma verbasci (Meyer), lacewings Chrysoperla plorabunda (Fitch) (Neuroptera: Chrysopidae) and Chrysopa nigricornis and the parasitic wasp Trechnites insidiosus (Crawford) (Hymenoptera: Encyrtidae) increased in abundance under IPM management. Biological-based IPM programmes have the potential to conserve natural enemies providing biological control in late summer when conventional sprays often fail due to pesticide resistance and inability to penetrate dense canopies.     

Landscape context and management effects on an important insect pest and its natural enemies in almond

Pest control mediated by organisms such as parasitoids is a valuable ecosystem service, particularly with regard to high costs, low effectiveness, and detrimental effects of some agrochemicals. This study examined infestation rates and abundance of pests and their natural enemies in organic and conventional almond orchards in California, differing in landscape context, understory plant cover, and plant species richness. Parasitoids of the commercially most important insect pest of almond, the Navel Orangeworm (NOW) were studied by rearing NOW in collected overwintering nuts. The indirect impact of vertebrate natural enemies of NOW were estimated by counting empty nut shells with feeding marks by wild birds and various mammals, found at the orchard floor. Mean nut infestation by NOW ranged from 0.8% to 37% per orchard and was reduced by parasitism rates, ranging from 0% to 22%, and vertebrate nut damage, ranging from 2% to 96% per orchard. The parasitoids were facilitated by a high proportion of natural habitat surrounding the orchards and high proportion of understory ground cover with vegetation. The vertebrate natural enemies were facilitated by a high proportion of natural habitat surrounding the orchards and plant species richness in the orchard understory. In conclusion, this study shows that pest control mediated by vertebrates and invertebrates promoted by near natural habitats can lower pest pressure by NOW larvae in overwintering almond. In case of the vertebrate nut damage this service might only be temporal and turn into a dis-service during and after harvest because the vertebrates continue to feed on the nuts and may also cause injuries to the trees.