噻虫嗪对丽蚜小蜂寄生烟粉虱的影响

为了明确噻虫嗪对烟粉虱天敌昆虫丽蚜小蜂Encarsia formosa的影响,在室内模拟田间噻虫嗪灌根和叶面喷雾2种施药方式,研究了施药后丽蚜小蜂的直接死亡率及其寄生Q型烟粉虱的生物学参数。结果表明,经噻虫嗪叶面喷雾后,丽蚜小蜂的死亡率高达98.10%,显著高于其它处理,丽蚜小蜂对烟粉虱若虫的寄生率为5.26%,显著低于其它处理;与清水对照相比,经噻虫嗪处理后丽蚜小蜂对烟粉虱的致死率降低,且叶面喷雾处理大于灌根处理;噻虫嗪灌根和叶面喷雾处理对丽蚜小蜂的羽化率和发育历期均无显著影响,但均能显著缩短丽蚜小蜂成虫的寿命。研究表明,噻虫嗪灌根施药方式对丽蚜小蜂的死亡率及寄生率影响较小,可将噻虫嗪灌根施药方式与释放丽蚜小蜂相结合以防治烟粉虱。     

Predators with a future as bioagents against glasshouse pests1

As a result of the application of Encarsia formosa, Phytoseiulus persimilis and Bacillus thuringiensis, and of the decreased use of pesticides, we have observed the spontaneous appearance of natural enemies not normally present in Bulgarian glasshouses. Clitostethus arcuatus has proved a competitive species with E. formosa on Nicotiana glauca, green capsicum and Hibiscus syriacus, attacked by Trialeurodes vaporariorum. On cucumber and capsicum plants infested respectively by Aphis gossypii and Myzus persicae, Cryptolaemus montrouzieri was established after spontaneously entering an experimental glasshouse. Some trials were carried out with the polyphagous bug Podisus maculiventris under laboratory conditions. It was able to use larvae of T. vaporariorum, M. persicae and A. gossypii as prey. On this basis, it seems quite promising to include this predator in IPM programmes as an additional bioagent against certain glasshouse pests during the autumn-winter-spring period.     

Research on and use of biological methods of pest control in glasshouse crops in Poland1

In 1966/1967, the predatory mite Phytoseiulus persimilis and the hymenopteran parasite Encarsia formosa were introduced into Poland. This introduction led to extensive research on the principles and practical use of biological and integrated programmes of pest control in glasshouse crops. Additional species were later introduced (Macrolophus costalis, Amblyseius mckenziei, Neoseiulus cucumeris, Cycloneda limbifer, Cryptolaemus montrouzieri), and research was also undertaken on local species such as Aphidoletes aphidimyza and Aphidius matricariae. At present, after 25 years of research, modem and effective mass rearing of natural enemies has been organized, and they are applied over 600 ha of glasshouse crops. For correct development of biological methods in glasshouses, new introductions, research, and mass rearing of new species are necessary.     

The toxicity of two pyrethroids to Encarsia formosa and its host Trialeurodes vaporariorum; Prospecting for a resistant strain of the parasite

The toxicity of bioresmethrin and deltamethrin has been studied on the host-parasite couple Trialeurodes vaporariorum-Encarsia formosa. Long term trials were used under laboratory conditions. The insecticides were applied to the plant at all stages of host and parasite development. The two products studied showed some toxicity to E. formosa. Bioresmethrin, a poorly persistent insecticide, could be used with care in integrated control; deltamethrin, a highly persistent product, must be excluded. Attempts to obtain strains of E. formosa resistant to deltamethrin were made. The selection pressure applied during 21 successive generations failed to produce a significant and stable resistance level.     

Effects of pesticide residues on ground-dwelling lycosid and micryphantid spiders in laboratory tests

The effects of residues of three commercial pesticides in common use in Europe against cereal pests, on two dominant spider species, a lycosid and a micryphantid, were evaluated in the laboratory. Insecticide assay methods for juvenile and adult hunting and adult web-building, ground-dwelling spiders are described. Results varied with different sprayed substrates and species. Fenvalerate was more toxic than other pesticides and had a longer residual effect on all spiders when tested on moistened sand than on filter paper. Endosulfan was of high initial toxicity on sand, but was more toxic on filter paper to both adults and juveniles ofPardosa spp. Pyrazophos was non-toxic to the spiders tested, regardless of substrate. In general, the lycosids were more affected by pesticides than web-building spiders because of their different life strategies. A sprayed sand substrate matched field conditions better as a method to test the effects of pesticides on ground-dwelling spiders.     

Guideline for the evaluation of side-effects of pesticides. Encarsia formosa

This guideline is concerned with the evaluation of the side-effects of pesticides on Encarsia formosa (ENCAFO) in the glasshouse. Encarsia formosa is used for biological or integrated control of greenhouse whitefly ( Trialeurodes vaporariorum (TRIAVA)). Because field-testing is laborious and costly, this guideline includes a sequential testing scheme involving three laboratory tests, which may serve to classify many pesticides as definitely harmless or harmful without having recourse to field tests. In particular, the very stringent residual contact test on adults (the most sensitive stage) allows products to be classed as definitely harmless, since experience has shown that no product so classed by this test is ever harmful in field tests. The direct contact test on pupae (the most insensitive stage) makes it possible to exclude as definitely harmful products which have ≥ 50% effect. Products which are not harmful to pupae in this test could still kill adults after emergence if they are sufficiently persistent. So a 3-day persistence test makes it possible to exclude further products as too persistent. Finally, only products which appeared potentially harmful in the first test, but were harmless to pupae and non-persistent, have to be field tested, by comparison with harmful and harmless reference products, to decide on the final rating.     

Integration of chemical and biological control systems for arthropods: Evaluation in a multitrophic context

The methods used to evaluate and categorise the effects of pesticides on beneficial arthropods are reviewed, including the potential significance of indirect, ‘sub-lethal’ activity and the importance of bioavailability of pesticides under semi-field or field conditions. Interspecific and intraspecific differences in the susceptibility of natural enemies (parasitoids and predators) to pesticides are considered, including the use of resistant strains in Integrated Pest Management (IPM) systems. The potential impact of pesticide resistance in the target pest on its natural enemies is also discussed. The need to assess the influence of the host plant/cultivar on the efficacy of pesticides for use in integrated control programmes (ditrophic effects) and of the possible effects of such chemicals on host plant/cultivar-pest-parasitoid systems (tritrophic effects) are then described with specific reference to the diamondback moth and key endolarval parasitoids. Finally, the potential for manipulation of tritrophic interactions to enhance parasitism by application of low doses of toxicants is demonstrated.     

一些农药对温室白粉虱的毒力及其抗药性测定

用11种农药对温室自粉虱(Trialeurodes vaporariorum Westw.)进行了室内毒力测定。结果表明:拟除虫菊酯类杀虫剂、灭螨猛对温室白粉虱各虫态毒力均高,并且随虫龄的增加,白粉虱的抗药性增强。稻丰散、乐果、氧化乐果对温室白粉虱若虫毒力尚可,但对其它虫态效果差。马拉硫磷、二嗪农、敌敌畏、洗衣粉除对一龄若虫有一定效果外,对其它虫态毒力极低。北京地区温室白粉虱对某些药剂已出现明显的抗药性。     

14种农药的非致死浓度对拟长毛钝绥螨繁殖和定居的影响

在室内测试了１４种农药对拟长钝缓螨的非致死浓度及其对定居和繁殖的影响。氯氰菊酯，粉锈宁，克螨特，三氯杀螨醇对拟长毛钝绥螨的繁殖，叶上定居及着卵量都有很大的影响。氧化乐果影响拟长毛钝绥螨的繁殖，对定居影响不大。天王星，高效灭百可，灭扫利，功夫不影响，镇量影响在植侏上定居和叶上着卵量。双甲脒，卡死克，阿波罗对拟长毛钝绥螨影响不显著。爱力螨克和尼索朗对拟长毛钝缓螨的繁殖，定居，着卵量均不良的影响。     

丽草蛉对柑橘木虱成虫的捕食功能反应及捕食偏好

为明确丽草蛉Chrysopa formosa对柑橘木虱Diaphorina citri成虫的生物防控潜能,在实验室条件下测定丽草蛉1、2、3龄幼虫和成虫对柑橘木虱成虫的捕食功能、搜寻效应及其种内干扰效应,并测定其对不同猎物的捕食偏好。结果显示,丽草蛉1～3龄幼虫和成虫对柑橘木虱成虫均有捕食行为,捕食功能反应均符合Holling II模型。丽草蛉1、2、3龄幼虫和成虫对柑橘木虱成虫的瞬时攻击率分别为0.247、0.393、0.769和0.509,处理时间分别为0.228、0.048、0.015和0.013 d,理论日最大捕食量分别为4.386、20.833、66.667和76.923头,控害效能分别为1.083、8.188、51.267和39.154。各虫态丽草蛉对柑橘木虱成虫的搜寻效应均随着猎物密度的增加而降低,其中3龄丽草蛉幼虫的搜寻效应下降趋势最大。当柑橘木虱成虫密度固定时,单头丽草蛉的日捕食量随柑橘木虱密度的增加而逐渐降低,其捕食作用受到自身密度的干扰,干扰效应方程为E=0.260P-0.351。当存在柑橘木虱与豌豆蚜Acyrthosiphon pisum两种捕食对象时,丽草蛉3...     

Fungicidal activity of substituted quinoxalines

Twenty substituted quinoxalines based on the structure of 6 (or 7)-methyl-3-phenyl-1, 2-dihydroquinoxalin-2-one, a fungicidally active photodegradation product of quinomethionate, were synthesised. Eleven of these compounds had ED₅₀ values, as protectant sprays against Podosphaera leucotricha, of 0.1 mmol or less; these compounds had an aromatic substituent at the 3-position of the quinoxaline ring. They were less active as protectant leaf dips against Erysiphe graminis f. sp. hordei than against Podosphaera leucotricha; none showed any systemic activity as a soil-applied treatment against Podosphaera leucotricha. One compound was more active than quinomethionate as an eradicant spray. In spore germination tests on fungi from different taxonomic groups, the quinoxaline derivatives were active against only one basidiomycete (Uromyces fabae), whereas quinomethionate showed a broad spectrum of activity. The possible significance of this difference in spectrum of activity with respect to the mode of action is discussed.     

丽蚜小蜂寄生对Q型烟粉虱生长发育的影响

为明确丽蚜小蜂寄生对Q型烟粉虱的影响,通过室内饲养观察不同龄期Q型烟粉虱被丽蚜小蜂寄生后的生长发育,并比较了被寄生后烟粉虱若虫的个体大小及死亡率。结果表明,2龄、3龄和4龄烟粉虱若虫被寄生后均能继续发育,2龄若虫蜕皮进入3龄和3龄若虫蜕皮进入4龄的时间与对照间无显著差异,而被寄生若虫的4龄期显著延长。对于同一龄期的烟粉虱若虫,丽蚜小蜂偏向于选择较大的个体寄生,2龄和3龄被寄生若虫发育后期个体比未被寄生个体大,但4龄时被寄生的个体在发育后期略小于未被寄生个体,显示丽蚜小蜂对不同龄期若虫的生长发育影响不同。2龄若虫死亡率为61.64%,显著高于3龄和4龄若虫;4龄若虫褐蛹率最高,为48.84%。表明无论寄生哪一发育阶段的烟粉虱若虫,丽蚜小蜂的寄生均为容性寄生,田间应用丽蚜小蜂防治Q型烟粉虱时在其若虫3~4龄时释放更适宜。     

Recent progress of highly efficient in vivo biological screening for novel agrochemicals in China

This paper describes the recent progress of in vivo biological screening for pesticides in China. According to the criteria, including the severity of damage caused by pests and the economic value of the crops, the investigated insects, pathogens, herbs and other species in the agricultural field were selected as the main screening targets for pesticides. Corresponding in vivo microscreening methods have been established and applied in the pesticide screening procedure, which has higher reproducibility, a shorter time and greater efficiency that offset the drawbacks of conventional methods for pesticide screening. Copyright © 2009 Society of Chemical Industry     

Pesticidal compounds from higher plants

Higher plants offer an excellent source of biologically active natural products. Over the centuries numerous plants have been exploited as sources of insecticides, but nowadays traditional botanical insecticides play only a minor role in world agriculture. Nevertheless, plant natural products still have enormous potential to inspire and influence modern agrochemical research. Few plant natural products will ever reach the market as products per se, but others will provide lead structures for programmes of synthetic chemistry and hopefully follow the success story of the synthetic pyrethroids. Structurally complex compounds, which are not amenable to synthetic chemistry programmes, may also have a role to play by validating new modes of action for pesticides. Examples are presented of compounds exhibiting insecticidal, fungicidal and herbicidal effects. Consideration is also given to the development of screening programmes to detect new compounds with interesting biological properties. Careful experimental design and thorough recording of procedures and data are crucial to success. Badly designed programmes afford only weakly active compounds or show effects which cannot be reproduced at a later date. Natural product chemistry, whether based on higher plants, micro-organisms or other sources, is a very difficult science, but there is little doubt that dedicated research will eventually be rewarded with exciting new lead structures for industrial application.     

Ovicidal and nymphicidal effects of some fungicides on the greenhouse whitefly<Emphasis Type="Italic">Trialeurodes vaporariorum</Emphasis>

Eggs and L1 nymphs of the greenhouse whiteflyTrialeurodes vaporariorum (Westwood) (Hem.: Aleyrodidae) on bean leaves were directly sprayed with the fungicides maneb and mancozeb at recommended rates for practical use. Strong ovicidal and nymphicidal effects were observed. These fungicides may prove to have practical use for integration in IPM programs for whitefly control, as they also exert low or no toxicity to the whitefly parasitoidEncarsia formosa. http://www.phytoparasitica.org posting April, 30, 2004.     

A Rapid Method for Screening Insecticides in the Laboratory

An efficient method for rapidly mass-screening insecticides for use against sap-feeding virus vectors is presented with a case study of 30 chemicals. The method permits large numbers of insecticides to be tested simultaneously and relatively inexpensively in a sequence of laboratory bioassays. The sequence is designed to find the most effective pesticide at the lowest concentration giving control without phytotoxicity. The system was derived to test candidate insecticides to control tomato yellow leaf curl virus vectored by the tobacco whitefly, Bemisia tabaci Gennad., the most serious pest of greenhouse and field tomatoes in the Middle East. Although the insecticides were all more efficacious in the laboratory than in the field, bioassay results were highly correlated with results from field trials, giving high confidence that the screening process selected only the most efficacious insecticides. Most of the insecticides accepted by the screening process have since been adopted by vegetable growers in Israel. The method is not intended to eliminate field efficacy trials, but to reduce the number of trials and treatments that need to be performed, thereby reducing costs. The method provides for the optimization of application rates which will contribute to the expected life of insecticides before resistance develops, and will also help to reduce environmental contamination. In addition, the method is suitable for estimating relative efficacy for pesticide benefits assessments, a required part of the (re-)registration process for pesticides in some countries. Although developed for screening insecticides against virus-transmitting sap-feeding insects, the method could be modified to assess the efficacy of insecticides in controlling other insect pests.     

The side-effects of pesticides onDiaeretiella rapae, a parasitoid of the turnip aphid (Lipaphis erysimi)

Diaeretiella rapae (M’Intosh.) is an endoparasite of the turnip aphid,Lipaphis erysimi (Kalt.) with a wide geographical distribution. The four Pesticides Nogos 50 EC at 600 ml per acre, Dimecron 50 WSC, Monofos 40 WSC and Tamaron 600 SL at 500 ml per acre, used in practice for the control of this pest, were tested for their side-effects onD. rapae. The parasitoid was reared on pottedBrassica napus plants infested with aphid under laboratory conditions (22±2°C, 60–70% rel. hum., 16 h light and 8 h dark). In one test, adult female parasitoids were exposed to fresh pesticide residues on glass plates and in another test, the pupae within aphid mummies were directly sprayed. The results revealed that Dimecron 50 WSC, Nogos 50 EC and Monofos 40 WSC were harmful causing 100% mortalitv toD. rapae followed by Tamaron 600 SL (97% moderately harmful) after 24 hours of application, compared to no mortality in control, where only water was sprayed. Directly spraying of pupae with Dimecron 50 WSC and Nogos 50 EC reduced adult parasitoid emergence to 9 and 7%, respectively, Monofos 40 WSC and Tamaron 600 SL to 3% compared to 78% emergence for the control within one week of treatment. The results showed that none of the tested pesticides was safe toD. rapae and according to the International Organization for Biological Control (IOBC) further testing under semi-field and field conditions is recommended.     

A novel screening method for rice allelopathic potential: the inhibitory‐circle method

Screening crop accessions for allelopathic activity is of paramount importance for crop allelopathy research. Previous bioassays often did not use a mixed culture of donor and target plants, did not use soil and were not conducted under natural conditions. In this study, we designed an inhibitory‐circle method in which a rice accession (donor plant) and Echinochloa crus‐galli (target plant) were cultured together in paddy soil under natural conditions. First, we determined that the highest allelopathic activity of allelopathic rice accession PI312777 was at the 5‐leaf stage, and the suitable distance of rice seedlings and E. crus‐galli was 12 cm apart. This method was then validated by a field test. A further 40 rice accessions were evaluated for allelopathic activity to E. crus‐galli using this method. Two rice accessions, PI312777 and Taichung Native 1, had highly allelopathic activity to E. crus‐galli (inhibitory rate > 50%), while another accession, Lemont, had non‐allelopathic activity. These experimental results were in accordance with previous studies using direct field experiments. The inhibitory‐circle method integrated three necessary conditions, that is donor and target plants grown together, with soil as the medium and under natural conditions for reliable results. The ‘inhibitory‐circle method’, which combined donor and target plants, soil medium and field conditions, can give reliable results in one step, compared with laboratory screening methods. Also, the ‘inhibitory‐circle method’ gave results in 30‐35 days, thereby substantially reducing the requirements for time, labour and cost.     

Evaluation of carrot resistance to alternaria leaf blight in controlled environments

The objective of this study was to find a technique for plant resistance screening to alternaria leaf blight (ALB), caused by the fungus Alternaria dauci , in controlled environments. Glasshouse and laboratory screening methods were compared using three cultivars and F₂ genotypes segregating for ALB resistance evaluated against self-pollinated F₃ field-grown plants. Plant disease was assessed through a disease index obtained from the size and number of symptoms on carrot leaves. The results indicated the value of glasshouse evaluation and the inadequacy of detached leaf and hypocotyl assays for carrot screening for ALB resistance. Spearman's rank correlation, applied to results obtained with both F₂ plants and their progeny, indicated that the optimal evaluation stage for ALB resistance in carrot is 20 days after inoculation. This test was powerful enough to be used as a prescreening test in breeding programmes.     

非致死浓度农药对智利植绥螨产卵孵化和定居的影响

在实验室内用6种农药的非致死浓度(LC_(0-0.7)),处理感染有叶螨卵的菜豆叶,观察对智利植绥螨产卵量和卵孵化率的影响。结果表明:尼索郎(50×10~(-6))和卡死克(50×10~(-6))对智利螨的产卵量和卵的孵化都没有有害影响。双甲脒(2×10~(-6))对智利螨的产卵量无影响,但卵的孵化率仅为对照的1/3。NC-129(200×10~(-6))、天王星(0.2×10~(-6))和功夫(0.05×10~(-6))均能降低智利螨的产卵量,比对照分别减少28.3％、17.8％和14.4％。尼索郎、卡死克和双甲脒不影响温室菜豆上智利螨的定居率,NC-129、天王星和功夫则有严重影响:对照组智利螨定居率为85％,NC-129组的定居率仅为25％,天王星和功夫处理后完全没有定居。试验指出,尼索郎和卡死克对智利螨属安全农药,NC-129对智利螨有较大的影响,双甲脒、天王星和功夫对捕食螨是有害的。