Toxicity of cyanogen to insects of stored grain

Range-finding studies on the toxicity of cyanogen to all stages of five species of stored product Coleoptera are reported. The species were Rhyzopertha dominica (F), Sitophilus granarius (L), Sitophilus Oryzae (L), Tribolium castaneum (Herbst), Tribolium confusum Jacquelin du Val and Ephestia cautella (Walker). Exposures for 24 h to cyanogen at 1.3 mg litre(-1) controlled all external stages. Control of internal stages of Sitophilus species was achieved by a 5-day exposure to initial concentrations between 13.7 and 27.4 mg litre(-1), whereas R. dominica was controlled at 13.7 mg litre(-1). Cyanogen showed similar toxicity to all tested external stages and, in this respect, was more similar to methyl bromide than to phosphine. Its toxicity to insects increased with both relative humidity and concentration of carbon dioxide. Cyanogen was toxic to insects whether applied as a gas or in an aqueous solution.     

Sodium channel mutations (T929I and F1534S) found in pyrethroid-resistant strains of the cigarette beetle,Lasioderma serricorne (Coleoptera: Anobiidae)

RNA-seq data analysis of cigarette beetle (Lasioderma serricorne) strains having different sensitivities to pyrethroids identified sodium channel mutations in strains showing pyrethroid resistance: the T929I and F1534S mutations. These results suggest that reduced sensitivity of the sodium channel confers the pyrethroid resistance of L. serricorne. Results also showed that the F1534S mutation mostly occurred concurrently with the T929I mutation. The functional relation between both mutations for pyrethroid resistance is discussed.     

Development of nanoalumina dust as insecticide against Sitophilus oryzae and Rhyzopertha dominica

This study aims to characterize and improve the insecticidal activity of nanostructured alumina dusts. To accomplish these goals, multiple solution based synthesis routes utilizing standard aluminum salt precursors were utilized to synthesize three unique types of alumina dust. These were compared with regards to morphology, particle size and surface area using electron microscopy and dynamic light scattering particle size analysis. Insect toxicity of the various dusts was assessed using two insect species that are pests of stored grain, Sitophilus oryzae and Rhyzopertha dominica. The dust synthesized using a modified glycine-nitrate combustion process consistently yielded greater mortality rates, and all dust types were more effective on S. oryzae than on R. dominica, although the difference varied across dust types. The data show that insecticidal activity is dependent on particle size, particle morphology and surface area but also indicated that minimizing particle size and maximizing surface area are not the sole dominant factors influencing efficacy. This study does however suggest that pesticide dusts can be engineered through modified synthesis to better target different insect species.     

Identification of a novel trait associated with phytotoxicity of an insecticide etofenprox in soybean

Synthetic insecticides are widely used to control pests in various crop fields. Especially in soybean [Glycine max (L.) Merr.] fields, the insecticide etofenprox, which is a pyrethroid derivative, has been used to manage hemiptera pests. To date, soybean phytotoxicity response has not been reported to etofenprox derivatives, two Korean cultivars, Danbaek and Kwangan, were first identified to show leaf shape shrinkage damage after etofenprox application. We confirmed that the causal substance for phytotoxicity is etofenprox and that it had dosage effects. Through genetic analysis using three F₂ populations, sensitivity to etofenprox is confirmed to be managed by a single dominant gene, and that gene is the same in Danbaek and Kwangan. Although further genetic research is required to identify the gene responsible for sensitivity to etofenprox, the results of this study will help to elucidate the interaction between plants and chemicals when breeding new cultivars or developing pesticides.     

Dynamic plant uptake model applied for drip irrigation of an insecticide to pepper fruit plants

BACKGROUND: Drip application of insecticides is an effective way to deliver the chemical to the plant that avoids off‐site movement via spray drift and minimizes applicator exposure. The aim of this paper is to present a cascade model for the uptake of pesticide into plants following drip irrigation, its application for a soil‐applied insecticide and a sensitivity analysis of the model parameters. RESULTS: The model predicted the measured increase and decline of residues following two soil applications of an insecticide to peppers, with an absolute error between model and measurement ranging from 0.002 to 0.034 mg kg fw^?1. Maximum measured concentrations in pepper fruit were approximately 0.22 mg kg fw^?1. Temperature was the most sensitive component for predicting the peak and final concentration in pepper fruit, through its influence on soil and plant degradation rates. CONCLUSION: Repeated simulations of pulse inputs with the cascade model adequately describe soil pesticide applications to an actual cropped system and reasonably mimic it. The model has the potential to be used for the optimization of practical features, such as application rates and waiting times between applications and before harvest, through the integrated accounting of soil, plant and environmental influences. Copyright © 2011 Society of Chemical Industry     

农业害虫抗药性及其治理

对农业害虫抗药性的定义、害虫抗药性现状、抗药性的发展因素、抗性产生的机理等方面进行了阐述,并介绍几种害虫抗药性治理方案。     

Enhanced efficiency of electrostatically charged insecticide aerosols

The bioefficacy of a standard domestic aerosol insecticide has been compared with that of a similar spray in which the droplets were electrostatically charged. The aerosol was charged without the need for an external power supply, by enhancing natural charge separation processes that occur during atomisation. The charge-to-mass ratio achieved was 1.1 x 10(-4) C kg-1, compared with 2.2 x 10(-5) C kg-1 for the standard aerosol. Efficiency was assessed for insects in free flight. A direct space-spray application method was used to study the bioefficacy of these aerosols on houseflies, Musca domestica, and an indirect space-spray method on houseflies and mosquitoes, Culex quinquefasciatus. Two levels of concentration of active ingredients were compared. At low concentrations of 1.57 g kg-1 of bioallethrin and 0.29 g kg-1 of bioresmethrin, the charged aerosol achieved a significant reduction in KDT50 (time at which 50% of the flies were knocked down), compared with the standard aerosol. In the direct spray application to houseflies, the KDT50 was reduced by 50%, while in the indirect spray the KDT50 was reduced by 40%. In the indirect spray of mosquitoes, the KDT50 was reduced by 22%. With higher active ingredient concentrations of 2.09 g kg-1 for bioallethrin and 0.39 g kg-1 for bioresmethrin, the charged aerosol also demonstrated faster knockdown than the standard, but the improvement was less marked. In the direct spray application to houseflies, the KDT50 was reduced by 21% compared with the standard aerosol, while in the indirect spray the KDT50 was reduced by 16%. In the indirect spray of mosquitoes, the KDT50 was reduced by 24%. The percentage mortality after 24 h was also increased with the charged aerosol. Charge carried by the droplets results in increased interception of the insecticide, as the droplets are attracted to the insects in flight and space charge effects within the aerosol could cause improved dispersion in the test chamber.     

几种杀虫剂对嗜虫书虱的触杀作用

采用滤纸药膜法比较了常用8种杀虫剂对嗜虫书虱Liposcelis entomophila的触杀作用,在药剂的推荐浓度下有机磷类杀虫剂对嗜虫书虱的急性触杀作用强于其它药剂。同时测定了杀螟硫磷、敌敌畏和溴氰菊酯(含增效醚)3种药剂对嗜虫书虱的触杀毒力,其24h内触杀作用的LC_(50)分别为9．3284、2．1440和7．5007μg/cm~2,但杀螟硫磷的LC_(95)为459．4949μg/cm~2,远高于敌敌畏的8．2453μg/cm~2和溴氰菊酯(含增效醚)的14．5274μg/cm~2。此外,48h内敌敌畏等有机磷杀虫剂对嗜虫书虱的毒杀速度较其它供试药剂快。     

山东省不同地区韭蛆种群对杀虫剂的抗药性

用胃毒触杀联合毒力法监测了山东省7个韭菜种植区的韭蛆种群对毒死蜱、辛硫磷、高效氯氰菊酯、高效氯氟氰菊酯、吡虫啉和噻虫嗪6种常用杀虫剂的抗性水平。结果表明:山东省各地区韭蛆种群对毒死蜱和辛硫磷的抗性已较为普遍,其中莘县种群对毒死蜱的抗性超过30倍;对高效氯氰菊酯的抗性为中等水平;泰安种群对供试的两种菊酯类药剂均产生了低水平抗性;而对吡虫啉和噻虫嗪,7个供试种群处于敏感或敏感性下降状态。     

Regional reversion of insecticide resistance in Helicoverpa armigera (Lepidoptera: Noctuidae) is associated with the use of Bt cotton in northern China

A continuous programme for monitoring resistance of Helicoverpa armigera (Hubner) to commonly used insecticides was undertaken for assessing the impact of Bt cotton planting on the evolution of the pest resistance from 1994 to 2002 in China. The bioassay results showed that the resistance levels per year in field populations of H armigera to lambda-cyhalothrin, phoxim and endosulfan decreased, respectively, to 9-15-fold, 11-14-fold and 6-8-fold in 2001-2002 from 197-262-fold, 52-74-fold and 18-38-fold before the cultivation of Bt cotton in 1997. This significant increase in susceptibility to insecticides is expected to result in a reduction in insecticide application for H armigera control in Bt cotton. It is concluded that Bt cotton is playing an important role in the long-term management of H armigera by increasing the potential for natural and chemical control of the pest.     

Fumigation toxicity of volatile natural and synthetic cyanohydrins to stored-product pests and activity as soil fumigants

Insecticidal fumigation toxicity of natural and synthetic cyanohydrins was evaluated with four stored-product pests: the lesser grain borer, Rhyzopertha dominica (F), the red flour beetle, Tribolium castaneum Herbst, the saw-toothed grain beetle Oryzaephilus surinamensis L, the maize weevil, Sitophilus zeamais (Motsch) and the house fly, Musca domestica L. The fumigation LC50 values were calculated by probit analysis. For house flies, all but one of the cyanohydrins tested were more potent than 1,3-dichloropropene (Telone). Three were as efficacious as chloropicrin. For the lesser grain borer, all cyanohydrins tested were more insecticidal than dichloropropene, and all but one were more potent than chloropicrin. Four were as insecticidal as dichlorvos. The acetate of 1-cyano-1-hydroxy-2-propene (CHP-ace) was also tested in soil for antifungal and antibacterial activity, and inhibition of weed seed germination. CHP-ace reduced the total soil bacterial and fungal counts significantly, and was effective in inhibiting the germination of weed seeds in soil, indicating a broad spectrum of activity as a soil fumigant.     

湖北省甜菜夜蛾田间种群抗药性监测

2006年采用浸叶法监测了湖北武汉、荆州、宜昌、襄樊和麻城5个地区甜菜夜蛾田间种群对10种药剂的抗药性。结果表明,5个种群对氯氰菊酯均已产生了高水平抗性(抗性倍数50.5~263.6);对毒死蜱属中—高水平抗性(抗性倍数36.0~371.5);对灭多威属低—中水平抗性(抗性倍数7.8~20.7);对虫酰肼、氟啶脲、多杀菌素和甲氨基阿维菌素苯甲酸盐的抗性都处于敏感—中水平抗性;除武汉种群对茚虫威的抗性达到高抗水平外,各种群对甲氧虫酰肼、虫螨腈和茚虫威的抗性都处于敏感—低水平抗性。5个甜菜夜蛾田间种群中以武汉种群和宜昌种群抗性水平相对较高。     

室内杀虫气雾剂初级暴露评估方法评述

杀虫气雾剂是常用的室内卫生杀虫剂,科学、合理、安全地使用杀虫气雾剂是保障居民健康的重要内容。目前我国有关室内杀虫气雾剂使用安全性的研究较少,尚未建立系统的风险评估程序。文章重点介绍了世界卫生组织(WHO)及美国环境保护署(EPA)等国际上广泛使用的室内杀虫气雾剂暴露评估方法,包括针对施药者的吸入暴露和经皮暴露评估,针对施药后居民的吸入暴露、经皮暴露以及儿童的手至口和物体至口暴露评估等。分析了我国开展室内杀虫气雾剂暴露评估所面临的暴露途径设定及特异性参数选择等问题,旨在为我国杀虫气雾剂产品的合理开发及安全使用提供科学的评价工具。     

Insecticide susceptibility of surviving Cotesia plutellae (Hym: Braconidae) and Diaeretiella rapae (M'Intosh) (Hym: Aphidiidae) as affected by sublethal insecticide dosages on host insects

The effects of sublethal dosages of insecticides applied to Plutella xylostella L. (Lepidoptera: Yponomeutidae) and Lipaphis erysimi Kaltenbach (Homoptera: Aphidiidae) on the insecticide susceptibility of the surviving endoparasitoids, Cotesia plutellae Kurdjumov (Hymenoptera: Braconidae) and Diaeretiella rapae (M'Intosh) (Hymenoptera: Aphidiidae), were studied in Shangjie, Minhou, China. The susceptibility to methamidophos and the sensitivity of acetylcholinesterase (AChE) to methamidophos and dichlorvos in the adults of host insects were substantially lower than those in the two parasitoids. The host insects were treated with sublethal dosages of methamidophos in P. xylostella and of methamidophos and avermectin in L. erysimi. The cocoon formation in the two parasitoids decreased significantly, from 35.0% (control) to 13.0% (with methamidophos treatment) for C. plutellae; from 20.6% (control) to 9.0% (with methamidophos treatment) and from 24.3% (control) to 16.7% (with avermectin treatment) for D. rapae. The susceptibility to methamidophos of the resultant emerging adults of the two parasitoids was found to be significantly lower than that of the control when the parasitoids were left in contact with the same dosages of methamidophos. The average AChE activity inhibition by methamidophos and dichlorvos in 34-60 adults of the two parasitoids that emerged from the treatments (15.1% and 31.8% respectively for C. plutellae, and 21.1% and 26.9% for D. rapae) was also significantly lower than those of the controls (55.4% and 48.3% respectively for C. plutellae, and 42.9% and 51.7% for D. rapae). The bimolecular rate constant (k(i)) values of AChE to methamidophos and dichlorvos in the adults of parasitoids without the insecticide treatment were 1.78 and 1.56 times as high as those that emerged from the host insects treated with methamidophos for C. plutellae, and 1.91 and 1.66 times as high as those in the case of D. rapae. It is suggested that there is a difference in AChE sensitivity to insecticides between the resultant emerging parasitoids with and without insecticide pretreatment. Furthermore, the introduction of the insecticides to the host insects could be an important factor in the insecticide resistance development of the endoparasitoids. The natural selectivity would favour the parasitoids that had developed an insensitivity to the insecticide(s).     

不同波长频振式杀虫灯对雷竹林昆虫诱捕效果比较

雷竹Phyllostachys praecox是我国特有的优良笋用竹种, 在南方竹产区经济发展中占据重要地位。随着竹林栽培面积的不断扩大, 竹林生物多样性和生态系统稳定性不断降低, 竹林害虫日益猖獗, 成为制约竹产业发展的重要因素之一。为了有效控制雷竹林害虫, 本试验首次将频振式杀虫灯应用到雷竹林趋光性害虫防治中, 选用6种不同波长的杀虫灯进行试验, 光源分别为365、380、395 nm的3种波长紫外光和420、460、520 nm的3种波长可见光, 明确雷竹林害虫发生情况及规律, 探究雷竹林中频振式杀虫灯的科学使用方法。试验结果表明, 395 nm波长杀虫灯不仅对筛胸梳爪叩甲、沟胸重脊叩甲等鞘翅目害虫和竹卵圆蝽、黑竹缘蝽等半翅目害虫诱杀效果最好, 而且对鳞翅目害虫也有一定的诱杀效果, 综合防治能力较好。365 nm波长杀虫灯对竹林鳞翅目害虫诱杀效果最好, 适用于竹笋夜蛾、竹织叶野螟、二色绿刺蛾等鳞翅目害虫为害严重的竹林。520 nm波长杀虫灯对膜翅目害虫的诱杀效果最好, 同时对半翅目害虫也有一定的诱杀效果, 适用于竹瘿广肩小蜂、刚竹泰广肩小蜂等膜翅目及竹卵圆蝽、黑竹缘蝽等半翅目害虫为害严重的竹林。本研究可为频振式杀虫灯监测防治雷竹林趋光性害虫提供理论依据。     

The effect of insecticide application sequences on the control and insecticide resistance status of the peach-potato aphid, Myzus persicae (Hemiptera:Aphididae), on field crops of potato

Experiments were done on commercial potato crops in the UK to investigate the effect of different insecticide sequences on the control and insecticide resistance status of Myzus persicae (Sulzer). The work was done to provide field validation of similar laboratory studies done in 'field simulators'. To ensure adequate aphid populations and to influence the initial resistance status of the aphid population, cultured M. persicae from a clone of known resistance status (esterase R1, kdr heterozygote, non-MACE (modified acetylcholinesterase)) were inoculated into both experiments. Two-spray programmes starting with lambda-cyhalothrin (a pyrethroid insecticide) gave poor control in comparison with programmes starting with pirimicarb (a carbamate insecticide) or pirimicarb-containing mixtures. This concurred closely with the results obtained from single applications in field simulator studies. Treatment sequences containing pymetrozine (a pyridine azomethine insecticide) were also effective, though slower-acting. This again concurs with field simulator studies. The proportions of aphids carrying different resistance mechanisms were largely unaffected by treatment in these experiments. The implications of these results for field control strategies are discussed.