几种药剂对烟蚜毒力的温度效应

在15℃、20℃、25℃、30℃及35℃条件下分别测定了吡虫啉、丁硫克百威和氰戊菊酯对烟蚜毒力的温度效应.结果显示,吡虫啉和丁硫克百威对烟蚜的毒力呈正温度效应,但随着温度上升,烟蚜对吡虫啉的敏感性变化比丁硫克百威大.吡虫啉毒力在35℃时为15℃时的7.12倍;而丁硫克百威为2.88倍.氰戊菊酯对烟蚜的毒力呈负温度效应,在35℃时的毒力约为15℃时的1/5.鉴于这些药剂的毒力受温度影响的规律,建议在气温较低时选用氰戊菊酯等负温度效应的农药,在气温较高时则选用吡虫啉等正温度效应的农药,以充分发挥农药的性能,减少农药使用量、降低防治成本.     

吡虫啉对意大利蜜蜂乙酰胆碱酯酶的亚致死效应

【目的】确定吡虫啉对意大利蜜蜂Apis mellifera的致死中浓度,探究吡虫啉对意大利蜜蜂乙酰胆碱酯酶的亚致死效应。【方法】本文采用药膜法、点滴法和饲喂法测定吡虫啉对意大利蜜蜂的毒力曲线,及蜜蜂接触吡虫啉后头部乙酰胆碱酯酶活性的变化。应用RT-q PCR技术研究饲喂LC5浓度吡虫啉后,蜜蜂乙酰胆碱酯酶基因Ace1和Ace2的m RNA相对表达量。【结果】饲喂法、点滴法和药膜法3种方法测定的吡虫啉对意大利蜜蜂的致死中浓度分别是7.15 mg/L、0.078 ng/蜂和51 ng/cm2。3种作用方式下,吡虫啉均抑制了乙酰胆碱酯酶活性;随着浓度增加,ACh E酶活性处于下降状态,但降低较少。LC5浓度的吡虫啉对蜜蜂ACh E活性具有明显影响,24 h内ACh E活性呈现增强-抑制-增强的趋势。饲喂蜜蜂LC5亚致死浓度的吡虫啉后,Ace1和Ace2被诱导表达,但在1、2和16 h与对照无明显差异。【结论】亚致死浓度的吡虫啉对蜜蜂乙酰胆碱酯活性具有抑制作用,并且存在明显的剂量效应和时间效应,对Ace1和Ace2具有诱导效应,酶活性水平和m RNA相对表达水平不一致。     

几种药剂对烟蚜毒力的温度效应

在15℃、20℃、25℃、30℃及35℃条件下分别测定了吡虫啉、丁硫克百威和氰戊菊酯对烟蚜毒力的温度效应。结果显示，吡虫啉和丁硫克百威对烟蚜的毒力呈正温度效应，但随着温度上升，烟蚜对吡虫啉的敏感性变化比丁硫克百威大。毗虫啉毒力在35℃时为15℃时的7．12倍；而丁硫克百威为2．88倍。氰戊菊酯对烟蚜的毒力呈负温度效应，在35℃时的毒力约为15℃时的1／5。鉴于这些药剂的毒力受温度影响的规律，建议在气温较低时选用氰戊菊酯等负温度效应的农药，在气温较高时则选用吡虫啉等正温度效应的农药，以充分发挥农药的性能，减少农药使用量、降低防治成本。     

三种杀虫剂亚致死浓度对川硬皮肿腿蜂繁殖和搜寻行为的影响

在实验室条件下通过药膜法研究了3种杀虫剂对川硬皮肿腿蜂Sclerodermus sichuanensis Xiao成蜂的毒力和对繁殖的亚致死效应,并采用EthoVision3.1行为仪分析了杀虫剂对其搜寻行为的影响.结果表明,川硬皮肿腿蜂对啶虫脒最敏感,致死中浓度LC50和亚致死浓度LC10分别为7.71和4.46 mg/L,其次为吡虫啉(11.22和6.68 mg/L)和功夫菊酯(27.72和9.36 mg/L).经啶虫脒、吡虫啉和功夫菊酯亚致死浓度(LC10)处理的肿腿蜂,亲代、F1和F2代的寄生成功率均受到抑制;经功夫菊酯处理的肿腿蜂,亲代单蜂产卵量显著增加(P＜0.05);经啶虫脒和吡虫啉肿腿蜂,亲代的出蜂率没有显著影响(P＞0.05),但对F1代影响显著(P＜0.05).经啶虫脒和吡虫啉亚致死浓度(LC10)处理的肿腿蜂搜寻行为变弱.结果表明,功夫菊酯对川硬皮肿腿蜂较安全;啶虫脒和吡虫啉对川硬皮肿腿蜂的繁殖和搜寻行为影响较大.研究结果对评估3种药剂对川硬皮肿腿蜂的安全性,为指导合理用药,协调化学防治和生物防治提供科学依据.     

低剂量杀虫剂对星豹蛛捕食效应的影响及其机理

探讨低剂量杀虫剂对蜘蛛捕食效应的影响及其生化机理。采用药膜法,测定了低剂量吡虫啉作用下,星豹蛛和甘蓝蚜敏感性、捕食效应以及成蛛体内乙酰胆碱酯酶(AChE)、谷胱甘肽S-转移酶(GSTs)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和中肠蛋白消化酶的活力变化。低剂量农药作用下,星豹蛛对甘蓝蚜的功能反应类型为HollingⅡ型,与对照组相比,随着猎物密度的增大星豹蛛的捕食量增加,寻找效应降低,对猎物的处理时间Th缩短,从而增强了对猎物的捕食作用;低剂量农药处理后,星豹蛛体内AChE和GSTs活性均显著低于对照组(P0.05),说明酶活性受到抑制,且抑制作用随吡虫啉浓度的增大而加强,随作用时间的延长而减弱;SOD,CAT和中肠蛋白消化酶活性显著增强,与对照组相比存在显著或极显著差异(P0.05),且随吡虫啉浓度增大和作用时间的延长而逐渐降低,最后接近对照组。低剂量杀虫剂作用下,蜘蛛体内AChE活性受到抑制,AChE敏感性降低,对神经递质乙酰胆碱的分解作用下降,使蜘蛛的兴奋性增加;GSTs、SOD、CAT等代谢酶活性发生变化,使蜘蛛的新陈代谢加速,从而刺激捕食;中肠蛋白消化酶的活性增强,提高了对猎物的消化吸收功能。总之,在低剂量杀虫剂作用下,星豹蛛通过外在的捕食行为和体内一系列酶系生理生化反应的综合作用促进蜘蛛对害虫的控制作用。     

不同温度效应杀虫剂诱导对绿盲蝽三种解毒酶活力的影响

【目的】为了明确解毒酶对绿盲蝽Apolygus lucorum防治药剂温度效应的影响机制。【方法】本文测定了绿盲蝽3龄若虫体内3种主要解毒酶活力随温度变化的"钟形"曲线,以及在不同温度效应杀虫剂诱导后对绿盲蝽体内解毒酶"钟形"曲线的影响。【结果】在供试温度10~40℃范围内,绿盲蝽体内3种主要解毒酶,在25℃时活力均最高,且显著高于其他温度处理。在不同温度下,4种不同温度效应杀虫剂诱导后对绿盲蝽体内解毒酶活力影响测定结果来看,谷胱甘肽-S-转移酶受杀虫剂诱导影响,可能参与了负温度效应杀虫剂溴虫腈的代谢,其在20~30℃的温度范围内,可能参与了吡虫啉和辛硫磷的部分代谢,而正温度效应杀虫剂氟铃脲在低温时毒力较低,可能与其诱导该酶在低温时活力升高相关。在15℃左右的低温时,绿盲蝽体内羧酸酯酶和多功能氧化酶易受氟铃脲和溴虫腈诱导而活力增加,而在20~35℃,这两种酶活力不易受杀虫剂诱导,且辛硫磷、溴虫腈和吡虫啉可对绿盲蝽体内两种酶活力产生一定的抑制作用。【结论】绿盲蝽体内解毒酶活力可明显受到温度影响,而在杀虫剂诱导条件下,其可对绿盲蝽防治药剂的温度效应产生显著影响。     

吡虫啉亚致死剂量对禾谷缢管蚜生长和繁殖的影响

室内测定了吡虫啉亚致死剂量对禾谷缢管蚜Rhopalosiphum padi(Linnaeus)连续两个世代实验种群生长和繁殖的影响。结果发现,吡虫啉LC10剂量处理禾谷缢管蚜成蚜后,可导致亲代成蚜种群的存活率、平均寿命和产蚜量均低于对照种群,但差异不显著;F1世代吡虫啉处理组与对照组禾谷缢管蚜种群的存活率、寿命和繁殖水平无显著差异。结果表明,吡虫啉亚致死剂量对禾谷缢管蚜连续两个世代实验种群的生长和存活无明显影响,未发现亚致死剂量刺激禾谷缢管蚜当代和子代成蚜的增殖现象。     

亚致死剂量吡虫啉对麦二叉蚜生存和繁殖的影响

【目的】为明确亚致死剂量的吡虫啉对麦二叉蚜Schizaphis graminum (Rondani)连续3个世代种群的生存和繁殖的影响。【方法】采用浸叶法测定吡虫啉对麦二叉蚜的LC_(50),经吡虫啉亚致死剂量LC_(40)处理麦二叉蚜后,测定并分析其连续3个世代实验种群生存和繁殖的变化。【结果】同一世代中,吡虫啉LC_(40)剂量处理麦二叉蚜后,可导致F_0世代麦二叉蚜种群的平均寿命、产蚜总数和繁殖期均显著低于对照组种群（P<0.05）,但F_1和F_2世代LC_(40)组试虫的存活率和繁殖相关参数与对照组相比无显著差异（P>0.05）。方差分析结果表明,在不同世代间LC_(40)组试虫的产蚜总数随世代数的增加而显著增多（F=6.38,P=0.002）,存活率、平均寿命、繁殖期随世代数的增加而逐渐增加。【结论】吡虫啉的LC_(40)剂量可显著抑制F_0世代麦二叉蚜个体的存活率和繁殖力,但随着世代数增加,吡虫啉LC_(40)组麦二叉蚜的生存和繁殖力逐渐恢复,F_1和F_2世代与对照组种群的生存和繁殖参数无显著差异。     

玫烟色拟青霉和吡虫啉对烟粉虱种群的联合控制作用

利用生命表技术评价了在网室条件下玫烟色拟青霉和吡虫啉对烟粉虱种群的控制作用。在0·3%吡虫啉 1×106分生孢子/ml、0·1%吡虫啉 1×106分生孢子/ml、10%吡虫啉、1·0×106个孢子/ml菌液、1·0×106个孢子/ml菌液连续施用2次等5个不同的处理区,玫烟色拟青霉对第一代和第二代烟粉虱的种群干扰作用控制指数(IIPC)分别为0·5476、0·6836、0·3123、0·7278、0·4959和0·1566、0·1625、0·9830、0·2532、0·1349。其中,以使用0·3%吡虫啉 1·0×106分生孢子/ml处理区对烟粉虱种群的控制效果最好。玫烟色拟青霉与低浓度的吡虫啉混合使用能较好地发挥联合控制作用,对玫烟色拟青霉的累积控制效应无负面影响。     

黄荆提取物对蚜虫的毒力及其与吡虫啉的联合毒力

采用浸渍法测定了黄荆二氯甲烷种子提取物、吡虫啉和氧乐果对苹果黄蚜、棉蚜和桃蚜的毒力,利用毛细管点滴法测定了黄荆二氯甲烷种子提取物与吡虫啉混配对棉蚜的联合毒力,采用皿内选择法测定了黄荆二氯甲烷种子提取物和吡虫啉等药剂对桃蚜的驱避效应.结果表明：黄荆二氯甲烷种子提取物对苹果黄蚜、棉蚜和桃蚜的LC₅₀分别为334.59、362.79和2685.80 mg·L^-1,对苹果黄蚜和棉蚜的杀虫毒力较高.黄荆二氯甲烷种子提取物与吡虫啉按1000 ∶1混用,其共毒系数可达177.45,增效作用显著.黄荆二氯甲烷种子提取物和吡虫啉对桃蚜均有明显的驱避活性,处理后24和48 h 对桃蚜的驱避率分别达55.75%、39.44 %和69.89%、65.43%.噻虫嗪和啶虫脒也有一定驱避活性,处理后24和48 h对桃蚜的驱避率达16.52%～33.68%.     

The biology of insecticidal activity and resistance

Identifying insecticide resistance mechanisms is paramount for pest insect control, as the understandings that underpin insect control strategies must provide ways of detecting and managing resistance. Insecticide resistance studies rely heavily on detailed biochemical and genetic analyses. Although there have been many successes, there are also many examples of resistance that still challenge us. As a precursor to rational pest insect control, the biology of the insect, within the contexts of insecticide modes of action and insecticide metabolism, must be well understood. It makes sense to initiate this research in the best model insect system, Drosophila melanogaster, and translate these findings and methodologies to other insects. Here we explore the usefulness of the D. melanogaster model in studying metabolic-based insecticide resistances, target-site mediated resistances and identifying novel insecticide targets, whilst highlighting the importance of having a more complete understanding of insect biology for insecticide studies.     

Impacts of sublethal insecticide exposure on insects — Facts and knowledge gaps

The biodiversity and biomass of insects is dramatically declining due to various anthropogenic factors. One of these factors is the use of insecticides to protect plants from pests. However, apart from the targeted pest insects, thousands of non-target organisms face traces of insecticides that are not lethal but can affect numerous traits of the individual, including development, physiology, behaviour and communication. In the present review, key facts on impacts of sublethal insecticide exposure on such traits are summarised. Attributable to various abiotic and biotic processes, insecticide concentrations may become sublethal in space and time. Nevertheless, these concentrations impede insect development, reducing growth and survival, but sometimes also enhance reproductive performance. The effects are species-specific, but sensitivity also differs within species depending on the developmental stage, sex and population. Furthermore, insecticide exposure influences several immunity pathways and causes changes in behaviour. Such changes are mostly studied on the level of behavioural traits. However, also effects on the consistency of overall individual behavioural phenotypes, i.e. personalities, should be investigated, which have consequences on individual fitness and on the effectiveness of biocontrol agents. Moreover, insecticides can act as info-disruptors, impeding signal production and perception during chemical communication at various levels. Finally, microbial symbionts may modify insect responses to insecticides, being of particular interest for biotechnological approaches. Here, methodological issues are discussed and knowledge gaps and potential future research directions are highlighted. Understanding the mechanisms of dose-dependent insecticide impacts on organisms and their cascading effects on higher levels of biological organisation and on subsequent generations are of utmost importance for proper insecticide use.     

红火蚁专性药剂红蚁净对剑尾鱼的急性毒性试验

以剑尾鱼Xiphophorus helleri为试验对象,初步研究了不同浓度的红蚁净(pyragne)对剑尾鱼的急性毒性。结果显示:LC50,24 h=974.99 mg/L,LC50,48 h=606.74 mg/L,LC50,72 h=542.00 mg/L。按《化学农药安全评价试验准则》评价:红蚁净为低毒药剂。预测其安全浓度为70.50 mg/L。在实际应用中,进入水体中的药剂浓度远远低于安全浓度,所以在池塘或其他养殖等非饮用水体边缘使用红蚁净,只要按药剂使用浓度和方法进行,对鱼类是安全的。     

Cost-comparison of DDT and alternative insecticides for malaria control

In anti-malaria operations the use of DDT for indoor residual spraying has declined substantially over the past 30years, but this insecticide is still considered valuable for malaria control, mainly because of its low cost relative to alternative insecticides. Despite the development of resistance to DDT in some populations of malaria vector Anopheles mosquitoes (Diptera: Culicidae), DDT remains generally effective when used for house-spraying against most species of Anopheles, due to excitorepellency as well as insecticidal effects. A 1990 cost comparison by the World Health Organization (WHO) found DDT to be considerably less expensive than other insecticides, which cost 2 to 23 times more on the basis of cost per house per 6 months of control. To determine whether such a cost advantage still prevails for DDT, this paper compares recent price quotes from manufacturers and WHO suppliers for DDT and appropriate formulations of nine other insecticides (two carbamates, two organophosphates and five pyrethroids) commonly used for residual house-spraying in malaria control programmes. Based on these 'global' price quotes, detailed calculations show that DDT is still the least expensive insecticide on a cost per house basis, although the price appears to be rising as DDT production declines. At the same time, the prices of pyrethroids are declining, making some only slightly more expensive than DDT at low application dosages. Other costs, including operations (labour), transportation and human safety may also increase the price advantages of DDT and some pyrethroids vs. organophosphates and carbamates, although possible environmental impacts from DDT remain a concern. However, a global cost comparison may not realistically reflect local costs or effective application dosages at the country level. Recent data on insecticide prices paid by the health ministries of individual countries showed that prices of particular insecticides can vary substantially in the open market. Therefore, the most cost-effective insecticide in any given country or region must be determined on a case-by-case basis. Regional coordination of procurement of public health insecticides could improve access to affordable products.     

埃玛菌素对小菜蛾幼虫的毒力及其对子代种群增长的影响

研究了不同温度下埃玛菌素（emamectin）对小菜蛾Plutella xylostella幼虫的毒力,并用生命表法研究了25℃下埃玛菌素亚致死剂量LC₃₀）处理小菜蛾3龄初期幼虫后对其子代的影响。结果表明,埃玛菌素为典型的正温度系数药剂,对小菜蛾幼虫的触杀毒力在温度16～31℃间提高了10倍左右,口服毒力在相同温度范围内提高1 000倍左右,显示了埃玛菌素对该虫极高的口服毒力。25℃下埃玛菌素亚致死剂量处理当代幼虫后,对其子代的存活和繁殖均有明显影响,处理组和对照组子代的世代存活率分别为3.7%和35.5%,平均产卵量分别为92.4和148.3,种群趋势指数分别为1.8和27.4,净增殖率（R₀）分别为3.66和33.81,内禀增长力（r_m）分别为0.0665和0.0978。     

Cost and mitigation of insecticide resistance in the maize weevil, Sitophilus zeamais

Abstract.  A common assumption in models of insecticide resistance evolution is the association between resistance and fitness costs in the absence of insecticides. There is empirical evidence of such associations, but their physiological basis (and mitigation) is little investigated. Pyrethroid-resistant populations of the maize weevil Sitophilus zeamais (Coleoptera: Curculionidae) offer this opportunity. Pyrethroid resistance in this species was initially observed in five Brazilian states by 1995, but the phenomenon apparently decreased and did not spread to other regions, probably due to the occurrence of a fitness disadvantage in resistant individuals in the absence of insecticides. The present investigation aims to verify whether differences in respiration rate and fat body morphology are related to differences in rate of development in Brazilian populations of S. zeamais resistant to insecticides, and thereby provide evidence for the existence (or not) of a physiological fitness cost acting against insecticide resistance in maize weevils. This may occur due to a possible energy trade-off between insecticide resistance and other physiological processes associated with development and reproduction. To achieve this, studies of the rate of development, respiration and fat body cytomorphology are carried out in one insecticide-susceptible (from Sete Lagoas) and two resistant populations (from Jacarezinho and Juiz de Fora) of S. zeamais . The resistant population from Jacarezinho shows that higher body mass is associated with higher energy reserves (larger trophocyte area) for development and reproduction, as well as for insecticide resistance. However, the resistant population from Juiz de Fora does not appear to have large enough energy allocation for insecticide-resistance expression and development and/or reproductive performance, suggesting a trade-off between resistance and other life history traits.     

The uptake of phorate, a systemic insecticide, applied as a slurry to wheat and mustard seeds

The absorption by plants of wheat and mustard of a systemic organophosphorus insecticide (phorate), applied as a slurry seed dressing, was studied by caging the aphid Rhopalosiphum padi (L.) on the foliage of wheat, and the aphid Brevicoryne brassicae (L.) and the Chrysomelid beetle Phaedon cochleariae (F.) on white mustard, grown from phorate-treated seed.
Wheat and mustard plants quickly lost their toxicity to insects when they were transplanted, suggesting that most of the insecticide from a slurry seed treatment passes into the soil and is picked up by the roots. That phorate or its derivatives occur in the soil was shown by tests of anticholinesterase activity. Insecticide can also pass into the seed of wheat and move to the growing embryo. Phorate becomes closely bound to the testa of mustard, but does not penetrate it to reach the cotyledons or other parts of the embryo. Mustard cotyledons can become contaminated by insecticide as they emerge through the soil.
Young and old leaves of both wheat and mustard depend on continued absorption of insecticide from the soil to maintain their toxicity. No insecticide moves from old to young leaves. Old leaves lose their toxicity to insects more slowly than young ones. When treated seeds are sown close together, the overlapping zones of insecticide round each seed can increase strength and persistence of insecticidal effect. This happens more with dimethoate, which readily dissolves in water, than with phorate, which is almost insoluble. At normal sowing rates the zones of insecticide round each seed would rarely overlap.
Roots of wheat and mustard from treated seed did not excrete insecticide, and the roots did not carry insecticide through the soil.     

Toxicity of certain insecticides toSturmiopsis inferens,a larval parasite of sugarcane moth borers

Susceptibility of adults and puparia ofSturmiopsis inferens Tns. [Tachinidae, Diptera] to 9 commonly recommended insecticide sprays against sugarcane pests was determined. The chemicals tested as emulsifiable concentrates include lindane 0.1%, endosulfan 0.1%, monocrotophos 0.05%, quinalphos 0.05%, malathion 0.1%, dimethoate 0.1%, cypermethrin 0.01%, fenvalerate 0.01% and decamethrin 0.0014%. Lindane, malathion, dimethoate monocrotophos and quinalphos were highly toxic, while decamethrin had little harmful effect to the adults when exposed for 6 h to filter paper impregnated or sugarcane shoot bits sprayed with the chemicals. However, the insecticides had no harmful effect on the puparia and adult emergence was normal from the puparia sprayed with insecticides. In another study, susceptibility of adults to soil application of lindane EC, carbofuran G, chlorpyriphos G, Sevidol G and whorl application of lindane G, chlorpyriphos G and Sevidol G was tested in pot culture. Except for soil application of lindane EC, all other chemicals had no harmful effect to the adults in pot culture experiment. In a field trial, commonly recommended insecticides against shoot borer,Chilo infuscatellus Snell.viz., soil application of granules of lindane, carbofuran, chlorpyriphos and Sevidol and folia spray of endosulfan did not affect the parasite activity. Institute Publication No 1030.     

Implications of gene amplification for evolution and management of insecticide resistance

Simulations were used to compare evolution of insecticide resistance predicted by a conventional two-allele model with predictions from three- and four-allele models that assume resistance is based on gene amplification. Results were similar between models when insecticide concentration was low or moderate. In contrast, when 10% of the population was not exposed to insecticide each generation, high insecticide concentrations slowed resistance development in the two-allele model, but caused rapid development of high levels of resistance in the three- and four-allele models. The presence of a third allele at an initial frequency as low as 10-7 doubled or tripled the rate of resistance development in some cases. Attempts to slow evolution of resistance by overwhelming it with high concentrations of insecticides are not likely to succeed if gene amplification or other mechanisms generate alleles that confer high levels of resistance.     

Environmental factors affecting the degradation of Dyfonate by soil fungi.

The ability of selected fungi to degrade the soil insecticide Dyfonate (O-ethyl S-phenyl ethylphosphonodithioate) into water-soluble, noninsecticidal metabolites was found to be dependent on the supply of nutrients, incubation time, temperature, pH, as well as other factors. With yeast extract as the carbon source (5 g/liter) and ammonium nitrate (1 g/liter) as the nitrogen source, both Rhizopus arrhizus and Penicillium notatum degraded the insecticide to a larger extent than with any other combination of nutrients used. With glucose as the carbon source, concentrations of ammonium nitrate above 5 g/liter inhibited the degradation of Dyfonate by R. arrhizus. Time-course studies on the metabolism of the insecticide indicated that Dyfonate was first absorbed by the fungal mycelium, where it was metabolized followed by the release of water-soluble, noninsecticidal, breakdown products into the culture media. The degradation appeared to involve the breakdown of Dyfonate into ethyl acetate soluble metabolites, such as ethylethoxyphosphonothioic acid, ethylethoxyphosphonic acid, methyl phenyl sulfoxide, and methyl phenyl sulfone. These compounds were then further degraded into water-soluble products. The optimum conditions for the degradation of the insecticide by R. arrhizus were observed at pH 6.0 to 7.0 and at 15-25 degrees C. Aged fungal mycelia were as active as mycelia in the logarithmic growth phase.