Onion maggot (Diptera: Anthomyiidae) resistance to chlorpyrifos in New York onion fields

A larval immersion bioassay was developed to identify susceptibility of onion maggot, Delia antiqua (Meigen) (Diptera: Anthomyiidae), to chlorpyrifos and to determine whether this assay could be used to predict control in onion fields. Laboratory colonies were established from larvae collected in New York onion fields during 2003 and 2004, providing us with test insects to use in bioassays. The larval assay effectively determined susceptibility of D. antiqua to chlorpyrifos, and results were congruent with an adult bioassay. However, use of similar-aged larvae (4 d old) in the assays was critical because larvae became more tolerant to chlorpyrifos as they aged. In a field survey, six of the 13 populations had LC50 values above the recommended field rate of 3,600 ppm (range 4,031-6,869). Over two successive seasons in the same field, susceptibility of D. antiqua to chlorpyrifos decreased in two of three fields (by 45 and 42%) and remained the same in another field, indicating that resistance is not predictable from year to year. Based on the relationship between damage in the field and LC50 values from 11 of the populations mentioned above, all five populations that had LC50 values above the field rate caused unacceptable levels of damage, whereas five of six populations that had LC50 values below the field rate did not cause serious damage.     

Comparison of chlorpyrifos resistance in Culex pipiens pipiens (Diptera: Culicidae) collected from Northern and Southern Tunisia

In this study, we investigated resistance to the organophosphates chlorpyrifos in Tunisian populations of Culex pipiens pipiens. Three field populations were collected from Northern and central Tunisia between 2003 and 2005 and used for the bioassays tests. Our results registered moderate and high levels of resistance to chlorpyrifos which ranged from 33.8 to 111. The chlorpyrifos resistant populations were highly resistant to propoxur indicated an insensitive acetylcholinesterase 1 (AChE 1). The highest frequency of AChE 1 resistant phenotypes (64%) was recorded in the most resistant population (sample # 1). Bioassays conducted in the presence of synergists showed that not esterases were involved as the resistance mechanism to chlorpyrifos. However, CYP450 was partly involved in the resistance of the most resistant sample (# 1). Starch electrophoresis showed that three esterases were present in studied samples: A2‐B2, A4‐B4 and B12. Results are discussed in relation to the selection pressure caused by insecticide treatments.     

黄曲条跳甲对毒死蜱敏感性差异的生化机制

采用生物测定方法测定黄曲条跳甲Phyllotreta striolata(F.)2个室内试验种群(蔊菜试验种群、上海青试验种群)和1个田间自然种群对毒死蜱的LC50值。结果表明,蔊菜试验种群对毒死蜱的LC50值最低,为30.3459mg.L-1;田间自然种群对毒死蜱的LC50值最高,为77.8448mg.L-1,与蔊菜试验种群相比的敏感性指数为0.39。对不同种群黄曲条跳甲乙酰胆碱酯酶(AChE)、羧酸酯酶(CarE)、谷胱甘肽-S-转移酶(GSTs)的活性测定结果表明,黄曲条跳甲田间自然种群AChE活性最低,与菜试验种群、上海青试验种群相比,差异极显著(P>0.01);田间自然种群GSTs活性最高,与蔊菜试验种群、上海青试验种群相比,差异极显著(P>0.01);黄曲条跳甲蔊菜试验种群CarE活性最低,田间自然种群CarE活性最高,二者差异极显著(P>0.01);说明黄曲条跳甲对毒死蜱的敏感性下降可能与AChE活性的降低,与CarE、GSTs的活性提高有一定的关系。     

Determination of the resistance to organophosphate, carbamate, and pyrethroid insecticides in Panamanian Anopheles albimanus (Diptera: Culicidae) mosquitoes

Introduction. The susceptibility of Anopheles albimanus to organophosphates, carbamates and pyrethroid insecticides was unknown in the Panama communities of Aguas Claras, Pintupo and Puente Bayano, located in the Amerindian Reservation of Madungandi. This region is considered a malaria transmission area, where An. albimanus is the main vector. Objective. The resistance to organophosphate insecticides, carbamates and pyrethroids was evaluated in field populations of the Anopheles albimanus in Panama. Materials and methods. Progeny of An. albimanus collected in three localities in the indigenous Madugandi region were exposed to bioassays of susceptibility to organophosphate insecticides (fenitrothion, malathion and chlorpyrifos), the carbamate (propoxur) and pyrethroids (deltamethrin, lambdacyhalothrin, cyfluthrin and cypermethrin). The protocols were in accordance with those established for adult mosquitoes by World Health Organization. Results. The three strains of the An. albimanus were resistant to the pyrethroid insecticides deltamethrin, lambdacyhalothrin, cyfluthrin and cypermethrin. Susceptibility remained for the organophosphate insecticides fenitrothion, malathion, chlorpyrifos, and the carbamate insecticide propoxur. Conclusion. The results provided important information to the vector control program, contributing to the application of new strategies on the use of insecticides, and thereby lengthening the life of the insecticide in use.     

Baseline susceptibility of Planococcus ficus (Hemiptera: Pseudococcidae) from California to select insecticides

Between 2006 and 2008, 20 populations of Planococcus ficus (Signoret), from Coachella and San Joaquin Valleys of California were measured in the laboratory for susceptibility to buprofezin, chlorpyrifos, dimethoate, methomyl, and imidacloprid. Toxicity was assessed using a petri dish bioassay technique for contact insecticides and by a systemic uptake technique for imidacloprid. Mixed life stages were tested for susceptibility to all insecticides except for buprofezin, which was measured against early and late instars (first, second, and third). Dose-response regression lines from the mortality data established LC50 and LC99 values by both techniques. Responses of populations from the two geographical locations to all five insecticides varied, in some cases significantly. Variations in susceptibility to each insecticide among sample sites showed a sevenfold difference for buprofezin, 11-fold to chlorpyrifos, ninefold to dimethoate, 24-fold to methomyl, and 8.5-fold to imidacloprid. In spite of susceptibility differences between populations, baseline toxicity data revealed that all five insecticides were quite effective based on low LC50s. Chlorpyrifos was the most toxic compound to Planococcus ficus populations as shown by lowest LC50s. Buprofezin was toxic to all immature stages but was more potent to first instars. The highest LC99 estimated by probit analysis of the bioassay data of all 20 populations for each compound was selected as a candidate discriminating dose for use in future resistance monitoring efforts. Establishment of baseline data and development of resistance monitoring tools such as bioassay methods and discriminating doses are essential elements of a sustainable management program for Planococcus ficus.     

Comparison of two commercial formulations of Bacillus thuringiensis var. israelensis for the control of Anopheles aquasalis (Diptera: Culicidae) at three salt concentrations

Anopheles aquasalis larvae are salt water tolerant, preferring concentrations between 10 and 20 parts per thousand (ppt). The larvicidal efficacy of two formulations of Bacillus thuringiensis var. israelensis (Vectobac-12AS and Bactivec), was investigated against An. aquasalis at salinities of 0, 10, and 20 ppt. A probit analysis was used to calculate the lethal concentrations (LC50 and LC95) for each product at each salinity. The LC50 and LC95 were higher for Bactivec than Vectobac-12AS, and for Bactivec, the LC50 and LC95 increased with salinity. Vectobac-12AS should thus be preferred to Bactivec for An. aquasalis control, especially in saline breeding habitats.     

Larvicidal activity of Tagetes patula essential oil against three mosquito species

Larvicidal activity of Tagetes patula essential oil was tested against the fourth instar larvae of Aedes aegypti, Anopheles stephensi, and Culex quinquefaciatus. Five different concentrations of essential oil were studied and the results were compared with that of synthetic insecticide, malathion. A. aegypti (LC(50) 13.57, LC(90) 37.91) was most susceptible followed by An. stephensi (LC(50) 12.08, LC(90) 57.62) and C. quinquefaciatus (LC(50) 22.33, LC(90) 71.89).     

Reduced susceptibility to DDT in field populations of Anopheles quadriannulatus and Anopheles arabiensis in Malawi: evidence for larval selection

Abstract.  Bioassays for insecticide resistance in adult mosquitoes were conducted on samples of Anopheles gambiae Giles s.l . (Diptera: Culicidae) species collected as larvae from breeding sites in the lower Shire Valley, Malawi. The results indicate full susceptibility to permethrin, deltamethrin and malathion, but reduced susceptibility to DDT in one sample from Thom (LT₅₀ of 8.39 min for females and 25.09 min for males). Polymerase chain reaction-based species identification of the mosquitoes assayed revealed a mixture of Anopheles arabiensis Patton and Anopheles quadriannulatus (Theobold). The LT₅₀ did not differ significantly between species. Genotyping of the L1014F and L1014S kdr alleles showed all mosquito specimens to be homozygous wild type; thus the reduced susceptibility detected is not attributable to target site insensitivity and instead is likely to be metabolic in nature. Anopheles quadriannulatus is characteristically zoophagic and exophilic. Indeed, of 82 Anopheles collected through knockdown collections within dwellings, only one was An. quadriannulatus and the rest were An. arabiensis . They are unlikely, therefore, to have been exposed to selection pressure arising from insecticide-treated net usage or to DDT indoor residual spraying. Therefore, it is suggested that this example of reduced susceptibility to DDT in An. quadriannulatus reflects selection in the larval stages.     

亚致死浓度吡虫啉和毒死蜱对柑橘木虱成虫组织蛋白酶基因表达的影响

昆虫组织蛋白酶属于多功能酶系,在昆虫生命活动中具有重要作用,但昆虫组织蛋白酶对化学农药的响应却鲜有报道。吡虫啉和毒死蜱是目前防治柑橘木虱Diaphorina citri常用的化学药剂。本研究旨在探究吡虫啉和毒死蜱亚致死浓度处理对柑橘木虱成虫组织蛋白酶基因表达的影响。本研究基于柑橘木虱的转录组数据库,同时结合NCBI数据库,通过Blast比对鉴定得到8个柑橘木虱组织蛋白酶基因,序列分析得出其均属于半胱氨酸蛋白酶家族且含有保守的组氨酸活性位点。研究采用浸叶法处理得到经吡虫啉和毒死蜱处理24 h对柑橘木虱成虫的致死中浓度LC50分别为97.88 mg/L和47.94 mg/L。采用荧光定量PCR（qPCR）分析这两种药剂亚致死浓度（LC20和LC50）胁迫下柑橘木虱成虫组织蛋白酶基因表达水平变化。结果表明吡虫啉胁迫显著下调柑橘木虱DcCath-B,DcCath-F,DcCath-L和DcCath-L1基因表达量;毒死蜱LC20浓度胁迫显著下调柑橘木虱DcCath-B,DcCath-L和DcCath-W基因表达量,LC50浓度胁迫下仅DcCath-B表达量显著下调,其他基因表达无明显差异。以上结果表明吡虫啉和毒死蜱亚致死浓度胁迫下,柑橘木虱成虫下调表达体内部分组织蛋白酶基因以响应此逆境。本研究为探索亚致死浓度吡虫啉和毒死蜱对柑橘木虱的毒理机制提供了一定的理论依据。     

毒死蜱亚致死剂量对二斑叶螨实验种群动态的影响

【目的】为探讨毒死蜱(Chlorpyrifos)对二斑叶螨Tetranychus urticae Koch种群动态的影响,室内研究了毒死蜱亚致死剂量对二斑叶螨实验种群成螨和若螨的生长发育、存活和繁殖情况的影响。【方法】用浸虫法进行测定,生命表方法分析亚致死效应。【结果】结果表明毒死蜱亚致死剂量LC25处理成螨后,雌成螨寿命、总产卵量、子代孵化率、性比与对照组无显著差异,其净增值率、内禀增长率、周限增长率以及种群加倍时间显著低于对照组。毒死蜱亚致死剂量LC25处理若螨后,总产卵量、净增值率、世代平均周期显著低于对照组,内禀增长率、周限增长率以及种群加倍时间与对照组无显著差异。扩散试验证明毒死蜱对二斑叶螨有较强的刺激扩散作用。【结论】以上结果说明毒死蜱亚致死剂量对不同发育阶段的二斑叶螨发育和繁殖的影响不同,毒死蜱对二斑叶螨的刺激扩散作用可能是引起二斑叶螨再猖獗的原因之一。     

山东省五个棉花产区绿盲蝽对药剂的敏感性检测（英文）

利用闪烁管药膜法测定了2009年山东省德州、滨州、梁山、曲阜和聊城5个棉花产区绿盲蝽Lygus lucorum Meyer-Dür对硫丹、马拉硫磷、毒死蜱、灭多威、丁硫克百威、吡虫啉、联苯菊酯和氟虫腈8种杀虫剂的敏感性,筛选出适合各地区的高效防治药剂。结果表明：5个地区绿盲蝽种群对马拉硫磷、毒死蜱、丁硫克百威、联苯菊酯和吡虫啉处于敏感性阶段。不同种群之间对灭多威、硫丹和氟虫腈的敏感性差异较大,其中聊城种群为最敏感种群,滨州种群对灭多威、 硫丹和氟虫腈的LC₅₀值分别为聊城种群的5.12,6.04和39.80倍;曲阜种群对灭多威、硫丹和氟虫腈的LC₅₀值分别为聊城种群的22.12,5.48和22.80倍。两种群对此3种药剂的敏感性下降,而其余种群仍处于较敏感阶段。8种药剂对绿盲蝽成虫的毒力按大小依次排序为：氟虫腈＞灭多威、联苯菊酯、硫丹＞马拉硫磷、毒死蜱＞丁硫克百威＞吡虫啉。2009年7-10月间德州夏津绿盲蝽种群对8种杀虫剂的敏感性变化极微。     

毒死蜱亚致死剂量对朱砂叶螨实验种群动态的影响

采用Jackknife统计推断技术和生存分析Wilcoxon (Gehan)技术,对寄主为桑树的朱砂叶螨种群水平上的亚致死效应进行了研究.结果表明, 在30 ℃±1 ℃、RH (70±15)%、16L∶8D条件下,朱砂叶螨卵受毒死蜱亚致死剂量LC₃₅处理后,雌成螨寿命、子代卵孵化率、性比与对照组无显著差异,而处理组每雌总产卵量(42.37±2.270)显著低于对照组(52.50±2433);处理组内禀增长率(0.3279±0.0033)显著低于对照组(0.3717±0.0043)     

Introduction of Culex toxicity into Bacillus thuringiensis Cry4Ba by protein engineering

Bacillus thuringiensis mosquitocidal toxin Cry4Ba has no significant natural activity against Culex quinquefasciatus or Culex pipiens (50% lethal concentrations [LC(50)], >80,000 and >20,000 ng/ml, respectively). We introduced amino acid substitutions in three putative loops of domain II of Cry4Ba. The mutant proteins were tested on four different species of mosquitoes, Aedes aegypti, Anopheles quadrimaculatus, C. quinquefasciatus, and C. pipiens. Putative loop 1 and 2 exchanges eliminated activity towards A. aegypti and A. quadrimaculatus. Mutations in a putative loop 3 resulted in a final increase in toxicity of >700-fold and >285-fold against C. quinquefasciatus (LC(50) congruent with 114 ng/ml) and C. pipiens (LC(50) 37 ng/ml), respectively. The enhanced protein (mutein) has very little negative effect on the activity against Anopheles or AEDES: These results suggest that the introduction of short variable sequences of the loop regions from one toxin into another might provide a general rational design approach to enhancing B. thuringiensis Cry toxins.     

Nutritional status and insecticide tolerance in German cockroaches (Orthoptera: Blattellidae).

The interrelationship of two extrinsic factors-nutrition and pesticide exposure-was studied in German cockroaches, Blattella germanica (L.). Amount of dietary protein had no effect on susceptibility of male German cockroaches to propoxur and chlorpyrifos; however, the source of protein produced significant changes in insecticide susceptibility. Increased total body lipids, carbohydrates, and uric acid may have resulted in increased tolerance to these insecticides. Three days of food or water deprivation (or both) caused significant differences in susceptibility to chlorpyrifos and propoxur.     

Lung cancer risk in north Indian population: role of genetic polymorphisms and smoking

Lung cancer (LC) is the leading cause of cancer-related mortality in developing as well as developed countries. Life style choices, particularly tobacco smoking, have been implicated as the main cause in the development of the LC. Despite the fact that majority cases of the LC occur among smokers, only 1–15% of smokers develop LC. In the present study, we have explored the role of genetic polymorphism, smoking habit and their association to LC in a cohort of north Indian population. The polymorphic genes explored were CYP1A1, GSTM1, GSTP1 and GSTT1 using techniques of Polymerase chain reaction (PCR), Restriction Fragment Length Polymorphism (RFLP), Real Time PCR (RT PCR), and gene sequencing. Genetic polymorphism was analysed in 253 normal participants (control) and 93 LC patients originating from Lucknow, India. Data were compared using odds ratio and Fisher Exact Test. We found that smoking increases the susceptibility to LC threefold (OR = 2.9; 95% CI: 0.9–2.8). The most significant risk for LC (OR = 3.2; 95% CI: 0.7–3.8) was found in the association of the homozygous variant of CYP1A1 gene at A2455G base change at Exon 7 (Val/Val) genotype. There was a marginally significant association between LC and GSTT1 null genotype (OR = 1.3; 95% CI: 1.0–1.7) while no significant risk association was found between GSTP1 polymorphism and LC. The present study demonstrates that the presence of null genotype of GSTM1/GSTT1 taken together with CYP1A1 (Val/Val) genotype increases the susceptibility to LC eightfold in comparison to CYP1A1 (Ile/Ile) and GSTM1/ GSTT1 genotype.     

Effects of Selected Chemical Pesticides on Agamermis unka (Nematoda: Mermithidae), a Parasite of the Brown Plant Hopper,Nilaparvata lugens

Selected commercial and technical grade pesticides were tested against the egg, preparasite and adult stages of Agamermis unka , a nematode parasite of the brown planthopper, Nilaparvata lugens . The commercial insecticide, diazinon (LC = 0.37 ppm), was most toxic to the 50 preparasites, followed by phenthoate (LC = 0.43 ppm), BPMC (LC = 0.44 ppm), IBP 50 50 (LC = 0.46 ppm), cartap hydrochloride (LC = 0.82 ppm) and buprofezin + isoprocarb 50 50 (LC = 1.11 ppm). The least toxic commercial pesticide tested was the fungicide, pencycuron 50 (LC = 2.19 ppm). Out of 12 technical grade insecticides tested, phenthoate, monocrotophos, 50 diazinon and carbofuran (LC = 0.37-0.46 ppm) were highly toxic to the preparasites, followed by 50 buprofezin, BPMC and fenitrothion (LC = 0.74-0.86 ppm). Fenthion, etofenprox, chlorpyrifos, 50 imidacloprid and MIPC (LC = 1.11-2.19 ppm) were the technical grade insecticides least toxic 50 to the preparasites. Most preparasites survived for up to 24 h at the low insecticide concentrations (0.63 and 0.31 ppm). Preparasites that were exposed to BPMC for 24 h at concentrations as high as 5.0 ppm and survived the treatments infected brown planthopper nymphs. Four selected insecticides-chlorpyrifos, BPMC, imidacloprid and carbofuran-had significant adverse effects on A. unka egg hatching. Eggs that were in the insecticide solution for 168 h fared poorly with imidacloprid having the best survival ( > 2% of the eggs hatching at 0.04 ppm). No eggs hatched from the other insecticide treatments. Three selected insecticides, BPMC, imidacloprid and chlorpyrifos, tested against adult A. unka showed that most adults survived the exposure to the insecticides between 0.31 and 2.5 ppm. At 5.0 ppm of BPMC or chlorpyrifos none of the adults survived, whereas with imidacloprid 70% of the adults survived. Egg deposition by the surviving adults was greatly reduced in those treated with the insecticides compared with those in the controls. Imidacloprid had some negative impact on the preparasites' ability to infect BPH nymphs, but it had the least detrimental effect of the insecticides tested on preparasite survival and on the eggs and adults of A. unka .     

白鲢肝脏CYP3A序列分析及毒死蜱对其抑制作用研究

CYP3A是I相解毒酶系CYP450家族中的重要成员,在肝脏解毒过程中发挥重要作用。首次克隆了白鲢肝脏CYP3A基因并研究了毒死蜱对该基因表达的影响。生物信息学分析预测结果表明,CYP3A基因编码513个氨基酸,其蛋白质分子量为58.8 ku,理论等电点为7.96。该蛋白是一个稳定蛋白且具有一定的亲水性。二级结构预测可知,CYP3A包含45.2%的α-螺旋、12.3%的延伸链、4.3%的β-折叠和38.2%的无规则卷曲,具有2个显著的跨膜结合区。急性毒性实验结果表明,毒死蜱对白鲢具有很高的毒性,其96h LC50为0.172 mg/L。另外,荧光定量PCR检测发现,毒死蜱对白鲢CYP3A基因表达有明显的抑制作用。       

Simultaneous analysis of chlorpyrifos and cypermethrin in cord blood plasma by online solid-phase extraction coupled with liquid chromatography-heated electrospray ionization tandem mass spectrometry

Chlorpyrifos and cypermethrin are the most used insecticides in Taiwan. Exposure to both pesticides has been associated with reproductive and developmental health effects in humans and animals. This study describes an online solid-phase extraction coupled with liquid chromatography-heated electrospray ionization tandem mass spectrometry (online SPE-LC/HESI/MS/MS) method to analyze chlorpyrifos and cypermethrin in cord blood of pregnant women. Calibration curves showed good linearity (r2 > 0.998) for both pesticides within the range of 0.1-100 ppb. Limits of detection (LODs) were 0.01 and 0.05 ppb and recoveries in cord blood were 97.2 ± 4.8% and 93.5 ± 9.5% for chlorpyrifos and cypermethrin respectively. After analysis of 396 samples, the mean concentrations of chlorpyrifos and cypermethrin were 0.38 and 1.08 ppb respectively. These results demonstrate that LC/HESI/MS/MS is effective for the simultaneous analysis of chlorpyrifos and cypermethrin in cord blood with excellent sensitivity and specificity and may also be effective for high throughput assay in future epidemiology studies.     

不同温度下毒死蜱和噻嗪酮对褐飞虱的毒力作用

为了明确温度对杀虫剂毒杀作用的影响,本文研究了5个温度梯度(22℃、25℃、28℃、31℃和34℃)下毒死蜱和噻嗪酮对褐飞虱的毒杀作用。结果表明毒死蜱在不同温度下对褐飞虱的毒力变化与噻嗪酮有所不同。处理时间相同时毒死蜱的LC50随温度升高而逐渐下降。毒死蜱处理24 h、72 h、120 h时,毒死蜱对褐飞虱的LC_(50)在22℃下分别的50.15、16.15和15.33 mg/L,而在34℃下分别降低为6.70、4.16和1.92 mg/L。在实验的5个温度下,噻嗪酮对褐飞虱的LC_(50)没有显著差异。同一温度下,噻嗪酮的LC50随处理时间的增加而降低,但没有显著差异。在全球变暖的大环境下,明确温度对毒死蜱和噻嗪酮的毒力影响状况,对于杀虫剂的合理使用具有一定的指导意义。     

Baseline susceptibility to bacterial insecticides in populations of Culex pipiens complex (Diptera: Culicidae) from California and from the Mediterranean Island of Cyprus

Bacterial insecticides play an increasingly important role in mosquito control. To establish guidelines for detecting resistance at an early stage, information on natural variation in susceptibility of insect populations to these insecticides is needed. Between 1990 and 1993, the susceptibility of Culex pipiens L. complex to Bacillus thuringiensis subsp. israelensis de Barjac and/or Bacillus sphaericus Neide was determined in 31 collections from California. These collections were undertaken before the widespread use of B. thuringiensis subsp. israelensis and before the registration of B. sphaericus in California. Seven collections from the Mediterranean island of Cyprus, where no microbial insecticides have been used, also were tested. The 1990-1991 California collections exhibited limited variation in susceptibility to B. thuringiensis subsp. israelensis. LC50 and LC95 values spanned about a three-fold and four-fold range, respectively. The 1993 Cyprus collections exhibited both higher mean LC values, and greater variability in those values, than the California collections. The LC50s for the Cyprus collections varied over a 10-fold range, whereas the LC50s varied over a 12.5-fold range. Variation in susceptibility to B. sphaericus among the 1991 California collections was about five-fold at the LC50 and LC95. No significant geographic variation in susceptibility to B. thuringiensis subsp. israelensis was observed among regions within California. Although variation in susceptibility was limited among California collections, the greater variability observed among the Cyprus collections and between the Cyprus and California collections illustrates the importance of establishing regional baselines to monitor accurately for changes in susceptibility.