Winter wheat pests and their natural enemies under organic farming system in Slovakia: Effect of ploughing and previous crop

Organic farming system of winter wheat was investigated in Solvakia over three years, 1995–1997. The system was carried out on a small scale (four plots of 50 m²). Neither pesticides nor inorganic fertilisers were applied. Effect of two treatments, ploughing and previous crop, on the community of pests and natural enemies was surveyed. There were two types of ploughing (shallow and deep) made in autumn before sowing. As previous crops, silage-maize and alfalfa were used each season. The effect of all factors was analysed by multivariate method, redundancy analysis (RDA) and Monte Carlo permutation to assess statistical significance. During three years, 37 taxons of pests and 27 taxons of natural enemies were recorded. The results of RDA showed that the community of insects (pests and natural enemies) was mainly influenced by temporal variation. The highest abundance of all insects was observed in 1996. The effect of the two treatments on the community of pests and natural enemies was less obvious. Pests were found to be significantly more influenced by ploughingthan by previous crop. Most of pests occurred more abundantly on plots with shallow ploughing and on plots after maize. Abundance of natural enemies were, however, significantly affected by previous crop. Majority of them were more abundant on plots after maize than after alfalfa. Ploughing had only marginally significant effect on natural enemies that were more abundant on shallow ploughed plots. Both ploughing and previous crop had only negligible effect on species diversity of natural enemies.     

Population dynamics of herbivorous insects and potential arthropod natural enemies on Alnus species in Kabale district, Uganda

Monitoring populations of pests and their natural enemies under different management situations and seasonal weather parameters provides extremely useful information for taking preventive measures against pest outbreaks. The abundance, spatial and temporal distributions of herbivorous insects and arthropod natural enemies on Alnus species were monitored at four sites in Kabale district, Uganda between June 1999 and August 2000. Chewing insects, dominated by Coleoptera (75%), constituted the majority of insect herbivores sampled. Dominant and potentially serious pests of Alnus included Apion globulipenne, an unidentified Chrysomelidae (Coleopt. 27), Phymateus viridipes, Coloborrtics corticina and a Cacopsylla species (Homoptera: Psyllidae). Spiders were the predominant natural enemies accounting for 64% of the total natural enemies encountered, followed by parasitic Hymenoptera (30%). There were marked spatial and temporal variations in arthropod abundance. Among sites, mean abundance of total insect herbivores and total natural enemies on A. acuminata over 15 months ranged from 3.8–8.5 and 3.3–4.7 individuals per 1-m branch length respectively. Over the same period, mean number of total insect herbivores and total natural enemies on A. nepalensis that was studied at only one site were 11.9 herbivores and 4.2 natural enemies per 1-m branch length. Populations of most insect orders increased in the wet season although the greatest herbivore abundance was evident in the dry season. Further studies are necessary on the impact and management strategies of the potentially important insect pests and natural enemies on Alnus.This revised version was published online in November 2005 with corrections to the Cover Date.     

洞庭湖区杨树有害生物及天敌昆虫调查

2007—2009年,通过线路踏查,标准地详查,室内饲养昆虫,灯光诱捕昆虫,查阅相关资料等方法,对洞庭湖杨树主栽区进行了杨树有害生物及天敌昆虫普查,普查发现洞庭湖区危害杨树的有害昆虫共计8目36科146种,病害12种,有害动物5种,有害植物4种,主要天敌昆虫13种。     

Weeds,aphids, and specialist parasitoids and predators benefit differently from organic and conventional cropping of winter cereals

The aphid–natural enemy interaction in winter wheat fields constitutes a complex system that has been frequently studied because of its implication for biological control. However, not all of the aphids living in cereal fields are crop pests, as there are also aphids living on weeds that may serve as alternative hosts or prey for aphid parasitoids or predators. In this context, a concomitant survey of the plant and insect communities was conducted to understand how different plant communities affect the abundance and richness of aphids and the interactions with their natural enemies. The plant community was split into functional groups (grasses, legumes and forbs), and the aphid community was divided into feeding groups according to their host preferences (specialists in grasses or forbs). The grass aphids, which dominated the total aphid catches, responded positively to grass cover, which was particularly enhanced in the conventional fields. Conversely, the forb aphids, which mainly conditioned the total species richness of the aphids, were closely correlated with the local abundance of legumes. The system of cereal aphid-parasitoids was enhanced in the conventional fields, where the abundance of grasses was higher, whereas the legumes of the organic fields indirectly played a key role in enhancing the richness of the parasitoids and the abundance of predators. Our findings indicate that a bottom-up effect exists throughout the plant community, aphids, and aphidophagous insects and that plant community characteristics should be considered to better understand cereal aphid control.     

Quantifying the respective and additive effects of nectar plant crop borders and withholding insecticides on biological control of pests in subtropical rice

Conservation biological control avoids the need for mass releases of costly agents and the risks associated with introducing exotic agents by promoting existing natural enemies. This is done by alleviating insecticide-induced mortality and by manipulating the habitat to provide resources such as nectar, but there is a dearth of information on the relative and interactive effects of these two approaches. Here we used a large-scale factorial experiment with plots comprised of entire fields to test the effects of, and interactions between, withholding insecticides and planting borders of sesame (Sesamum indicum) on natural enemies and pests over 2 years. We used yellow sticky traps, sweeping netting and sentinel bait plants to monitor natural enemies and pests in the canopy and basal zones of the rice crop. Numbers of rice planthopper egg parasitoids and lepidopterous egg parasitoids in the rice canopy, as well as planthopper parasitism rates, were significantly greater in plots that were unsprayed and bordered by sesame, and scarcest in sprayed crops without sesame. Spraying of sesame-bordered crops gave parasitoid numbers similar to sprayed crops without sesame. Spiders in the canopy were significantly reduced in numbers by spraying, but there was no main effect of sesame borders. This study demonstrates that withholding insecticides and sowing nectar plant borders each have measurable as well as additive benefits on in-crop densities of ecosystem service providers responsible for predating and parasitising pests but the identity of the natural enemy determines the impact of these management practices.     

Using flower strips to promote green lacewings to control cabbage insect pests

Habitat management improves biological control by increasing the abundance and fitness of natural enemies through the provision of floral resources along field edges or between crops. Among the natural enemies reliant on flower resources, green lacewings often stand out due to their abundance, predation capacity and polyphagy. We evaluated the impact of tailored flower strips on the enhancement of natural enemies, especially green lacewings, in three organic cabbage (Brassica oleracea) farms in Southern Sweden. Insects were sampled from the flower strips, and cabbage pests and predators were visually recorded in the crop. In a laboratory assay, the pollen feeding preferences of Chrysoperla carnea (Stephens, 1836) were evaluated in a dual-choice test. The pollen consumed by the Chrysopidae was extracted from laboratory and field specimens, then quantified and identified. Flower strips were found to attract predators and parasitoids, whose abundance increased as flowers bloomed. Cabbage plants next to the flower strips showed lower pest infestation as compared to cabbage plant control, although no significant differences were observed in the number of predators. Chrysopidae used flower strips as feeding, reproduction and shelter sites and mainly consumed pollen from Phacelia tanacetifolia Benth. Under laboratory conditions, C. carnea showed a preference for P. tanacetifolia and Coriandrum sativum L. pollen over Borago officinalis L. and Fagopyrum esculentum Moench. We show that tailored flower strips could be an efficient tool for enhancing beneficial arthropods and should be considered in integrated pest management for cabbage crops.

     

人工林物种多样性与害虫的控制

根据国内外的最新研究成果,从人工林害虫可持续控制的需求出发,对利用物种多样性与系统稳定性控制虫害的可能性、人工林物种多样性与害虫控制的关系及其内在作用机制、天然林与人工林在抑制虫害能力上的差别进行综述,分析人工林植物物种多样性与昆虫物种多样性对害虫控制的影响,认为植物物种多样性主要从植食性昆虫搜寻寄主植物,植物营养的差异对植食性昆虫取食和发育的影响,及种类组成不同的植物群落中植食性昆虫天敌数量的变化3个方面影响害虫的发生;要通过调节植物群落中昆虫物种的多样性影响目标害虫的种群数量,既要维护其天敌类群的稳定,也要使与害虫处于同一营养层次的其他植食性昆虫有足够的多样性,甚至也要保护和利用中性、中位及顶位昆虫.对人工林害虫的控制,可借鉴天然林自控虫害的原理,采用生态育林、封山育林及生物技术措施,逐步调整林分的结构,提高其物种多样性,增强林分自身的抗虫能力.     

Insect pest problems in tropical agroforestry systems: Contributory factors and strategies for management

Agroforestry trees are attacked by a wide spectrum of insects at all stages of their growth just like other annual and perennial crops. Pest management in agroforestry has not received much attention so far, but recent emphasis on producing high value tree products in agroforestry and using improved germplasm in traditional systems, and emergence of serious pest problems in some promising agroforestry systems have increased awareness on risks posed by pests. Insects may attack one or more species within a system and across systems in the landscape, so pest management strategies should depend on the nature of the insect and magnitude of its damage. Although greater plant diversity in agroforestry is expected to increase beneficial arthropods, diversity by itself may not reduce pests. Introduction of tree germplasm from a narrow genetic base and intensive use of trees may lead to pest outbreaks. In simultaneous agroforestry systems, a number of factors governing tree—crop—environment interactions, such as diversity of plant species, host range of the pests, microclimate, spatial arrangement and tree management modify pest infestations by affecting populations of both herbivores and natural enemies. Trees also affect pest infestations by acting as barriers to movement of insects, masking the odours emitted by other components of the system and sheltering herbivores and natural enemies. In sequential agroforestry systems, it is mostly the soil-borne and diapausing insects that cause and perpetuate damage to the common hosts in tree—crop rotations over seasons or years. An integrated approach combining host-plant resistance to pests, exploiting alternative tree species, measures that prevent pest build up but favour natural enemies and biological control is suggested for managing pests in agroforestry. Species substitution to avoid pests is feasible only if trees are grown for ecological services such as soil conservation and low value products such as fuelwood, but not for trees yielding specific and high value products. For exploiting biological control as a potent, low cost and environmentally safe tool for pest management in agroforestry, research should focus on understanding the influence of ecological and management factors on the dynamics of insect pest-natural enemy populations. Scientists and policy makers in national and international institutions, and donors are urged to pay more attention to pest problems in agroforestry to harness the potential benefits of agroforestry.This revised version was published online in November 2005 with corrections to the Cover Date.     

Arthropod diversity of cocoa farms under two management systems in the Eastern and Central regions of Ghana

Diversity of insect communities can be used as bioindicators for change in the environment especially in farms under different management systems. In line with that, we conducted a research on insect species associated with cocoa under organic and conventional management systems in the Eastern and Central regions of Ghana. Insect collection was done using Hand height visual count, Canopy, and “Knock down”, pitfall, coloured bowl and fruit-baited traps. A total of 13,742 individual insects belonging to 138 species from 63 families and 12 orders were recorded in the study. Insect abundance and diversity were generally higher in organic farms compared to conventional farms with Oecophylla longinoda as the most dominant species in both management systems and especially more dominant in organic cocoa farms. Our study revealed that most of the insect species recorded were known cocoa pests although there was high abundance of beneficial insects too. Some of the pest species were Planococoides njalensis, Salhbergella singularis, Helopeltis spp and Pseudococus spp, while some of the beneficial insects recorded were Pheidole spp, Tegenaria spp, Camponotus spp, Crematogaster spp. We can conclude that cocoa farms are potential habitats for insect biodiversity conservation. We recommend that management and/or agronomic practices used in cocoa farms should be geared towards protecting beneficial organisms for instance pollinators and natural enemies by effectively suppressing insect pest populations while enhancing good seed production.

     

Arthropod pests and their natural enemies in stored crops in northern Namibia

A survey of stored product pests, their natural enemies, grain storage and pest management approaches in northern Namibia was conducted. The survey revealed five types of crop commodities (pearl millet, sorghum, cowpea, maize, feed mixture) stored in four types of grain stores (baskets, bag stags-flat stores, concrete bin, metal containers). No synthetic pesticides or plastic sheeting was recorded. Wooden-ash natural pesticide is the only protectant used. Ten insect pest species were found affiliated to the orders of Coleoptera (Attagenus fasciatus, Callosobruchus subinnotatus, Cryptolestes ferrugineus, Oryzaephilus surinamensis, Rhyzopertha dominica and Tribolium castaneum), Lepidoptera (Corcyra cephalonica, Sitotroga cerealella), Psocoptera (Liposcelis paeta) and Blattodea (Blattella germanica). Out of these, seven species were recognized as new stored-products pests for Namibia. Although listed for southern Africa region, no storage pest-mites (Acari) and Sitophilus spp., Prostephanus sp. or Trogoderma sp. beetles were traced. We found four new species of natural enemies of storage pests recruiting from insects (Habrobracon hebetor, Cephalonomia wattersoni, Brachymeria sp.) and mites (Blattisocius tarsalis). The occurrence of natural enemies indicates a potential for pest bio-control in Namibian grain stores.     

广西油茶病虫害种类调查及发生特点

通过对广西油茶（Camellia oleifera）主产区的病虫害种类调查,发现广西区内为害油茶的病害有12种,虫害84种,介绍了广西油茶主要病虫害发生为害特点、发展趋势,并提出对油茶园进行科学管理、加强病虫害防治研究和保护利用天敌的应对措施.     

荔枝园昆虫群落优势功能团的季节演变及其相关性

以功能团为研究单元,对不同处理荔枝园昆虫群落季节演变规律进行了研究.结果表明:咀嚼害虫、刺吸害虫、捕食性天敌以及中性昆虫是昆虫群落的优势功能团;两处理区各害虫、中性昆虫功能团种群数量变动基本一致;无公害区捕食性天敌数量及优势度多数月份要高于常规区,但又显著低于对照区;中性昆虫是维持捕食性天敌种群数量的主要功能团;无公害防治对害虫的防治效果与常规化学防治相当,有利于维持果园昆虫群落的稳定.     

石羊河下游白刺有害生物种类及防治对策

调查了石羊河下游白刺有害生物种类,分析了其发生特点和原因,得出石羊河下游白刺群落有森林病害6种、害虫20种、有害动物6种、有害生物天敌29种,并提出了白刺有害生物防治对策.     

秦皇岛市区园林昆虫种类调查初报

本文作者利用2年时间,对秦皇岛市区园林昆虫区系进行了调查。初步摸清了秦皇岛市区园林害虫种类及天敌昆虫资源情况。共查出园林害虫50科235种,园林天敌昆虫10科22种。为科研、教学及生产提供了依据。     

浙江省香榧病虫害及害虫天敌种类调查

文章系浙江省近年来香榧病虫害和害虫天敌的调研总结。重点对省内主要香榧生产县(市)进行调查。共收录害虫57种，分别隶属8目28科，病害5种，以及害虫天敌16种，分别隶属7目11科。收集浸渍幼虫标本50余号，针插标本2200余号，其中包括了大多数的主要害虫。并且对绝大部分的标本在收集的第一现场进行了摄影记录。     

Influences of trees on abundance of natural enemies of insect pests: a review

In this article we review the use of natural enemies in crop pest management and describe research needed to better meet information needs for practical applications. Endemic natural enemies (predators and parasites) offer a potential but understudied approach to controlling insect pests in agricultural systems. With the current high interest in environmental stewardship, such an approach has special appeal as a method to reduce the need for pesticides while maintaining agricultural profitability. Habitat for sustaining populations of natural enemies occurs primarily at field edges where crops and edge vegetation meet. Conservation and enhancement of natural enemies might include manipulation of plant species and plant arrangement, particularly at these edges; and consideration of optimum field sizes, number of edges, and management practices in and near edges. Blending the benefits of agricultural and forestry (windbreak) systems is one promising approach to field edge management that has additional benefits of wind protection and conservation of desirable wildlife species.Journal series 10549 of the Agriculture Research Division, University of Nebraska-Lincoln. This material was prepared with the support of USDA Agreement 91-COOP-1-6592 for the USDA/EPA Program, Agriculture in Concert with the Environment. Any opinions, findings, conclusions or recommendations expressed herein do not necessarily reflect the views of the US Department of Agriculture or the US Environmental Protection Agency.     

The role of integrating agroforestry and vegetable planting in structuring communities of herbivorous insects and their natural enemies in the Neotropical region

The integration of agroforestry plots with ephemeral crops such as vegetables on the farm scale can probably serve as a refuge and source of beneficial insects. Therefore, agroforestry systems possibly represent an alternative that favors ecosystem services and help growers in the transition process from conventional to agro-ecological agriculture. This study aimed to understand the role of introducing agroforestry systems in structuring insect communities, with consequences for the abundance of herbivore and natural enemies, contributing to farm management and favoring biological control as an ecosystem service. Field surveys showed that agroforestry systems can harbor more species than horticultural crops, independent of the functional group. They also contain a greater diversity of herbivores and an even greater diversity profile of natural enemy communities. Agroforestry systems served as a source of natural enemies that can colonize horticultural crops when herbivores are present. As a consequence, natural enemies can establish a numerical response to herbivore abundance, but their communities are also affected by stochastic factors related to climatic conditions. Thus, agroforestry systems and agro-ecological practices might favor an agriculture based on the maintenance and conservation of ecosystem services.     

红梨园果实采摘后害虫及天敌的组成与数量特征

2006年9～11月,在昆明市盘龙区松花乡红梨科技示范园中对红梨果实采摘后的主要害虫及天敌的组成与数量特征进行调查,发现害虫16种,天敌19种.梨蚜为主要害虫,瓢虫为主要天敌.分析了梨蚜与其主要天敌瓢虫的消长动态,表明天敌的发生与蚜虫密切相关,且有明显的时间和数量跟随关系.     

Banker plants and landscape composition influence colonisation precocity of tomato greenhouses by mirid predators

Journal of Pest Science - Conservation biological control involves manipulation of the environment to enhance the effectiveness of natural enemies in controlling crop pests. In this study, we...     

Unravelling pest infestation and biological control in low-input orchards: the case of apple blossom weevil

Low-input farming is an alternative production system that provides a great opportunity to disentangle the natural mechanisms regulating crop pests, since neither pests nor their natural enemies are disrupted by pesticides. Here, we use a key apple pest in Europe, the apple blossom weevil (Anthonomus pomorum), as a model case to unravel the factors driving pest infestation and its biological control in a low-input context, namely the cider apple orchards of NW Spain. We applied a holistic approach based on the complete life cycle of the pest and combined large-scale observation (23 orchards) with small-scale experimental assessment. Weevil attack (0.4–37.4% of flowers) increased with the proportion on apple trees in the immediate orchard neighbourhood and with semi-natural woody habitat in the surrounding landscape and decreased with tree distance to orchard edge and apple bloom level. Thus, the prevalence of the pest depended on the availability of the various resources required for foraging, egg-lying and overwintering. Three types of natural enemies supplied complementary pest control by preying on weevils at different stages in their life cycle: seven parasitoid species attacked immature weevils (6.4–81.5%), while the additive effects of birds and crawling arthropods were evident in terms of the removal of adult weevils (31–44%). We conclude that the effective biological control of A. pomorum can be achieved in low-input systems to maintain the pest at non-harmful levels, through combined management of the pest, its habitat and its natural enemies.