杀虫剂混用或加增效剂对瓜-棉蚜增效作用及机制的研究

1987年,根据瓜-棉蚜(Aphis gossypii Glov.)对拟除虫菊酯和有机磷杀虫剂的抗性机制,研究了一些有机磷化合物或增效剂,对这两类杀虫剂的增效作用及增效机制。在试验的化合物中,马拉氧磷和虫螨磷对氰戊菊酯有明显的增效作用,其共毒系数分别为814.4和1067.2。有机磷杀虫剂对氰戊菊酯的增效程度与其对α-乙酸萘酯羧酸酯酶(α-酯酶)的抑制能力呈极显著相关。异稻瘟净对马拉氧磷,TPP对久效磷也具有明显的增效作用,而异稻瘟净对乐果,TPP对氧化乐果则没有增效作用。     

桃蚜对有机磷和氨基甲酸酯抗性机制研究

1986—1990年对桃蚜(Myzus persicae Sulz.)抗药性的系统研究结果表明,北京地区桃蚜对乐果的抗性最高为230倍,氧乐果为185倍,马拉硫磷为32倍,喹硫磷为19倍,倍硫磷为123倍,马拉氧磷为100倍,毒死蜱为39倍,抗蚜威为245倍,灭多威为39倍,呋喃丹为84倍,对西维因没有产生明显抗性。TPP 与氧乐果、乐果混用分别增效3.2倍和12.1倍;异稻瘟净与倍硫磷、马拉硫磷混用,共毒系数分别为236和234。增效醚(Pb)使乐果和氧乐果分别增效7.1倍和6.0倍。说明桃蚜的抗药性与羧酸酯酶和多功能氧化酶(MFO)有关。在敏感种群中,β-NA 羧酸酯酶活性大于0.5(OD_(555)值/蚜·15分钟)的个体仅占1%,而在抗性种群中,这种类型的个体占78%—98%。不同抗性水平的桃蚜种群,乙酰胆碱酯酶对抑制剂敏感度的分布与其抗性水平具有明显的相关性,马拉氧磷、抗蚜威对乙酰胆碱酯酶的抑制中浓度(I_(50)),抗性种群是敏感种群的20倍和150倍。北京地区桃蚜的抗药性与磷酸酯酶和 GSH—S-转移酶没有明显的关系。     

增效醚对棉铃虫的毒理学研究

本文以棉铃虫 3龄幼虫为试虫材料对增效醚 (PBO)的毒理学进行了研究。结果表明 ,PBO对棉铃虫(H elicoverp a armigera) 3龄幼虫的 L D50 为 5.7532 μg/ larva;在活体抑制实验中 ,用 4 μg/ larva的剂量点滴处理1h后 ,幼虫体内乙酰胆碱酯酶 ACh E的活性被抑制 4 8.31% ,羧酸酯酶 Carb E被抑制 4 4 .97% ,多功能氧化酶MFO被抑制 6 0 .82 % ;在离体抑制试验中 ,PBO对 ACh E、Carb E和 MFO的抑制中率 (I50 )分别为 3.35× 10 -7mol/ L、4 .4 6× 10 -7mol/ L和 1.4 2× 10 -7mol/ L ;PBO对酯酶的抑制为不可逆抑制。因此 ,PBO的增效机理在抑制代谢酶系的水平上并不是专一的 ;对于棉铃虫而言 ,PBO具有明显的杀虫活性 ,用其进行增效实验判断MFO是否参与抗性时应注意 PBO的这一特点 ;同时文章还证明了磷酸三苯酯 (TPP)和顺丁烯二酸二乙酯(DEM)抑制作用的专一性。     

多杀菌素对甜菜夜蛾多酚氧化酶和羧酸酯酶的影响

报道了多杀菌素对甜菜夜蛾Spodopetera exigua(Hübner)多酚氧化酶(PPO)和羧酸酯酶(CarE)的影响, 多杀菌素对甜菜夜蛾表现了很高的毒力,对三龄幼虫的LC50值为0.80 mg/L。离体条件下,1.0×10-3~0.5 mg/L多杀菌素对甜菜夜蛾多酚氧化酶的抑制率超过50％,且表现为随药剂浓度的增加抑制能力增强的趋势。活体条件下,0.1~0.8 mg/L多杀菌素在处理的早期诱导虫体内多酚氧化酶的活性增加,但12 h后却显著抑制多酚氧化酶的活性。1.0×10-3~1.0 mg/L多杀菌素在离体条件下对羧酸酯酶不表现任何抑制作用,但活体条件下同样能诱导虫体内羧酸酯酶活性增强。     

三种不同来源胆碱酯酶用于农药残留快速检测的比较

本实验以罗非鱼肌肉胆碱酯酶、Sigma C2888乙酰胆碱酯酶及商品化农药残留检测试剂盒为检测酶,使用酶抑制法进行检测,比较了12种不同浓度农药对这三种酶酶活力抑制情况。结果表明,9种有机磷杀虫剂和3种氨基甲酸酯类杀虫剂对罗非鱼肌肉胆碱酯酶都有较强的抑制作用,IC50值均10×10-6μg/m L。敌敌畏对胆碱酯酶的抑制作用最强,其IC50值为0.031×10-6μg/m L;灭多威的抑制能力最弱,IC50值为50.91×10-6μg/m L。8种农药(丁硫克百威、敌敌畏、辛硫磷、对硫磷、甲胺磷、乐果、马拉硫磷、甲基异柳磷)对罗非鱼肌肉胆碱酯酶的抑制作用Sigma C2888,检测试剂盒ACh E对7种农药(呋喃丹、灭多威、辛硫磷、对硫磷、甲胺磷、马拉硫磷、敌百虫)的灵敏度高于Sigma C2888。与罗非鱼肌肉胆碱酯酶比较,呋喃丹、灭多威、辛硫磷、甲胺磷、敌百虫对检测试剂盒胆碱酯酶的抑制更强。     

棉蚜不同抗性品系羧酸酯酶比较

用分光光度计终点测定法和酶标仪动力学测定法对3个抗性水平不同的棉蚜品系和1个敏感品系的羧酸酯酶进行了研究。棉蚜的不同抗性品系羧酸酯酶对α-乙酸萘酯(α-NA)和β-乙酸萘酯(β-NA)的水解活性具有极显著的相关性(r=0.95,n=400)。两种测定法均显示出R1、R2和R3品系的羧酸酯酶比活力明显高于S品系。以α-NA为底物时,用酶标仪动力学测定法研究表明,S、R1、R2和R3棉蚜品系羧酸酯酶活性分别为38、85、198和762mOD·min~(-1)·aphid~(-1);与4个品系的抗性程度比较,酶动力学方法的测定结果更可靠。     

瓜-棉蚜对有机磷及氨基甲酸酯杀虫剂抗性机制研究

从1983年开始就北京及河北省廊坊、香河和涿鹿县四个地区瓜-棉蚜(Aphis gossypiiGlov.)对18种有机磷及2种氨基甲酸酯杀虫药剂进行了抗性系统监测,与苏联瓜蚜(A.gos-sypii Glov.)敏感系毒力值(LC_(50))进行比较,抗蚜威最高达7887.7倍,马拉硫磷357.8倍,乐果128.6倍,敌敌畏83.5倍,乙酰甲胺磷72.1倍;而对喹硫磷、甲基辛硫磷、呋喃丹及溴氯磷则相当敏感,LC_(50)值在45.2—186.0 ppm之间。其抗性谱大致呈交叉型交互抗性。酶系测定结果表明,瓜-棉蚜的乙酰胆碱酯酶(AChE)敏感性降低与抗药性关系最为密切,氧化乐果和抗蚜威对AChE的I_(50)值与其Log LC_(50)(ppm)呈显著相关(P<0.05)。四个地区的瓜-棉蚜AChE对底物(乙酰硫代胆碱ATCh)的米氏常数(Km)及最大反应速度(Vmax)值均无明显差异,但ATCh浓度超过10~(-2)mol/L时,对AChE还没有明显的抑制作用。瓜-棉蚜α-乙酸萘酯羧酸酯酶与对久效磷的抗性呈正相关,面与抗性较高的乐果则无相关性。多功能氧化酶活性的高低与抗药性水平有关,乐果加PB(1:1)也有一定增效作用。GSH-S-转移酶活性与瓜-棉蚜抗性不相关。     

四种羧酸酰胺类杀菌剂对辣椒疫霉菌三个不同发育阶段的毒力比较

室内离体条件下测定了4种羧酸酰胺类(CAAs)杀菌剂双炔酰菌胺、烯酰吗啉、丁吡吗啉和氟吗啉对辣椒疫霉3个不同生长发育阶段的抑制活性。结果表明:4种杀菌剂抑制辣椒疫霉菌丝生长的EC50值分别为1.95×10-2、1.41、1.85、2.31 μ g/mL;对病菌孢子囊形成的抑制效果最好,其EC50值分别为2.00×10-4、1.50×10-3、2.60×10-3、4.30×10-3 μ g/mL;抑制游动孢子萌发的EC50值分别为4.60×10-3、0.373、0.494、0.635 μ g/mL。4种CAAs杀菌剂对辣椒疫霉的抑制作用均高于对照药剂甲霜灵、吡唑醚菌酯及嘧菌酯。     

三种双酰胺类杀虫剂制剂对环境非靶标生物的急性毒性

采用"OECD化学品测试准则"和"化学农药环境安全评价试验准则"方法,以赤子爱胜蚓、非洲爪蟾、斜生栅藻、大型溞、斑马鱼,意大利蜜蜂以及家蚕为受试生物,测定了20%氟虫双酰胺水分散粒剂、200g/L氯虫苯甲酰胺悬浮剂和200g/L溴氰虫酰胺悬浮剂3种双酰胺类杀虫剂对环境非靶标生物的急性毒性。结果表明:氟虫双酰胺、氯虫苯甲酰胺、溴氰虫酰胺3种药剂对赤子爱胜蚓、非洲爪蟾、斜生栅藻和斑马鱼的急性毒性均为低毒,但对大型溞的48 h-EC_(50)值分别为1.51×10~(-2)、2.58×10~(-3)、7.63×10~(-2)mg/L,对家蚕的96h-LC_(50)值分别为6.11×10~(-2)、0.12和0.30 mg/L,均为剧毒;氟虫双酰胺和氯虫苯甲酰胺对意大利蜜蜂为低毒,但溴氰虫酰胺对其的48h经口LC_(50)值和接触LD_(50)值分别为2.90 mg/L和3.71×10~(-2)μg/bee,均为高毒。研究表明,虽然双酰胺类杀虫剂对多数非靶标生物毒性较低,但在水体环境和桑蚕区以及作物开花期仍需谨慎使用。     

微量滴度酶标板法测定棉蚜(Aphis gossypii Glover)酯酶特性与有机磷抗性的关系

通过生物测定表明高密棉蚜对有机磷的抗性高于北京棉蚜,用紫外分光光度计比色法(A法)及微量滴度酶标板法(B法 )测定高密棉蚜及北京棉蚜的α-乙酸萘酯酯酶活力和α-乙酸萘酯酯酶动力学。北京棉蚜和高密棉蚜的α- NA酯酶活力分别为 2.23、4.48(A法 )和1.13、3.30(B法)μmol·mg-1pro.·min-1,高密、北京棉蚜的酶活之比为 2 .00(A法 )、2 .92(B法) ;北京棉蚜、高密棉蚜的Km值分别为:6.06×10-5、7.51× 10-5(A法 )和 7.66×10-5、8.87×10-5 (B法) mol·L-1,Vmax值为2.53、5.82(A法)和1.28、3.61(B法)μmol·mg-1·min-1。比较紫外分光光度计比色法及微量滴度酶标板法的测定结果,表明微量滴度酶标板法的测定结果是可靠的。     

Present status and countermeasures of insecticide resistance in agricultural pests in China

Of the 23 species of agricultural pest known to resist insecticides in China, 4 are cotton pests, 4 rice pests and 5 are pests of brassicae. In the green rice leafhopper, malathion resistance is caused by increased carboxylesterase (CarE) activity, which plays a more important role in the resistance to dimethoate than the mixed-function oxidases (mfos). The in-vitro and in-vivo results are in agreement with studies of synergism of malathion and dimethoate by TPP and EBP. These synergists delay the development of resistance, and EBP when added to malathion has limited the development of resistance to malathion in the green rice leafhopper. In the cotton aphid, resistance to organophosphates involves several factors: acetylcholinesterase (AChE) insensitivity, high CarE activity, slight (× 2) increase in glutathione S-transferases (GSH-ases), mfo activity as well as reduced penetration. In vitro, the I₅₀ of the insensitive AChE is × 14 that of S aphids, and anaphthyl-acetate CarE hydrolysing activity is 70 times greater in R than in S aphids. Insecticide mixtures, alternation or rotation can delay build-up of resistance; resistance to malathion and trichlorfon was delayed in Culex pipiens pallens when the two insecticides were used together. Used singly each insecticide selected for high resistance within 25 generations. Mosaic rotation of dimethoate and fenvalerate delayed the onset of insecticide resistance in Lipaphis erysimi pseudobrassicae.     

辛氰和乐氰混剂对甘蓝桃蚜抗性演化的影响

用辛硫磷与氰戊菊酯,乐果与氰戊菊酯的最佳配比及其相应单剂对甘蓝桃蚜进行抗性选育,汰洗２０代时桃蚜对两种混剂的抗性,分别为４．２０和２．６８倍,比相应单剂的抗性发展速度慢,尤其比氰戊菊酯单剂（２８９倍）更慢,表明上述两种混剂都可延缓桃蚜的抗性发展。用酶抑制剂进行增效应用测定结果表明：Ｋ１和ＴＰＰ对辛硫磷和乐果都有增效作用,尤以Ｋ１的增效作用更显著,其增效比分中辊为１０５３和３８,说明桃蚜对辛硫磷和乐     

In-vitro Metabolism of a Novel Monocrotophos Derivative by Rat and Japanese Quail

NADPH-dependent inhibition of hepatic microsomal carboxylesterase by a derivative of monocrotophos (coded as RPR-5) was studied in rat and Japanese quail as a measure of monooxygenase-catalysed activation of RPR-5. There was NADPH-dependent inhibition of hepatic microsomal α-naphthyl acetate esterase (carboxylesterase) both in rat and quail, indicating monooxygenase-catalysed formation of an oxon that subsequently phosphorylated α-NaE. The pattern of in-vitro metabolism of ¹⁴C-labelled RPR-5 by 11000g supernatant (11-S), microsomes and 105000g supernatant (105-S) fractions of rat and quail livers suggested the involvement of microsomal monooxygenases and carboxylesterases. A radiolabelled metabolite (M2) was tentatively identified as an acid produced by carboxyl esterase attack. In rat, metabolism by microsomal and cytosolic (105-S) carboxylesterases appeared to predominate with relatively little oxidative metabolism. In quail, putative microsomal carboxylesterase hydrolysis of RPR-5 was much lower than in the rat with almost neglible hydrolysis by cytosolic fractions. Also, production of M₂ by quail microsomes was substantially reduced after addition of NADPH, suggesting inhibition of a carboxyl esterase by the oxon of RPR-5. Differences in this detoxification of RPR-5 between rat and quail may be an important factor in determining selective toxicity and the results underline the importance of relating metabolism to toxicity when selecting animal models for toxicity testing.     

Studies on hydrolases in various house fly strains and their role in malathion resistance

Aliesterase, carboxylesterase, and phosphorotriester hydrolase activities in six house fly strains were studied in relation to malathion resistance. Selection of two susceptible strains with malathion for three generations resulted in an increase in both carboxylesterase activity and LD₅₀ of malathion, indicating that the increased detoxication by the enzyme was the major mechanism selected for malathion resistance. With the highly resistant strains, however, the carboxylesterase activity alone was not sufficient to explain the resistance level, and the involvement of additional mechanisms, including phosphorotriester hydrolase activity, was suggested. The E₁ strain, which had high phosphorotriester hydrolase activity but normal or low carboxylesterase activity, showed a moderate level, i.e., sevenfold resistance. Upon DEAE-cellulose chromatography, two or three esterase peaks were resolved from susceptible, moderately resistant, and highly resistant strains. The substrate specificity, the sensitivity to paraoxon inhibition, and the $\text{α}\text{β}$ ratio of malathion hydrolysis were studied for each esterase peak from the different strains. The results suggested the existence of multiple forms of esterases with overlapping substrate specificity in the house fly.     

Hydrolysis of malathion by rabbit liver oligomeric and monomeric carboxylesterases

The hydrolysis of malation by rabbit liver oligomeric and monomeric carboxylesterases (CE's) (EC 3.1.1.1) results in the formation of a mixture of α- and β-monoacids. A new chromatographic procedure was utilized to investigate the formation of α- and β-monoacids. The oligomeric carboxylesterase (oCE) produced an $\text{α}\text{β}$ ratio of monoacids of 4.55, and the monomeric carboxylesterase (mCE) produced an $\text{α}\text{β}$ ratio of monoacids of 2.33. The ratios of α- and β-monoacids were independent of the initial concentration of malathion and remained constant over the time course of the reaction. Kinetic studies demonstrated that the K_m values were the same for the corresponding reactions which produced either α-monoacid or β-monoacid with the same enzyme. Since both carboxylesterases are electrophoretically pure, the kinetic data strongly supports the theory that the reactions which produced α- and β-monoacids are catalyzed by the same active site. Comparison of the k_cat and K_m values governing the hydrolysis of malathion by the two esterases, together with their relative abundance in liver, indicated that the oCE would be responsible for about 80 to 98% of the hydrolytic detoxication of malathion by rabbit liver.     

Effect of hepatic enzyme inducers on the in vivo and in vitro metabolism of dicrotophos,dimethoate, and phosphamidon in mice

Daily 75 mg/kg phenobarbital ip injections for 3 days or 25 ppm dieldrin in the diet of mice for 14 days caused an increase in liver cytochrome P-450 and blood B-esterase. Liver A-esterase was not significantly increased. Under in vitro conditions, phenobarbital and dieldrin induced the oxidative as well as hydrolytic metabolism of dicrotophos, dimethoate, and phosphamidon by liver homogenates or combined microsomes plus 105,000g supernatant fractions. The concentration of dimethoxon was increased more than fourfold by the pretreatments after incubation for 4 hr at 37.5°C with NADPH added. The organophosphorus insecticides used in this study were not metabolized as well by the liver microsomes alone or 105,000g supernatant alone, as by the combination of microsomes and 105,000g supernatant. Under in vivo conditions in mice, phenobarbital and dieldrin treatments increased the urinary recovery of metabolites in the initial 6 hr after [¹⁴C]carbonyl-dimethoate or [¹⁴C]N-ethyl-phosphamidon administration. Analysis of urine showed that the inducers caused a more than sixfold increase in dimethoxon recovered and twofold increase in water-soluble nontoxic metabolites within 6 hr after dimethoate administration. With phosphamidon both inducers increased the rate of metabolism, and the total recovery in aqueous and chloroform fractions was decreased. These results suggest that increased dimethoate toxicity after phenobarbital and dieldrin treatments in whole animals results from stimulation of the activation of dimethoate to dimethoxon, while the increase in hydrolytic products after both pretreatments results in decreased toxicity of the direct acetylcholinesterase inhibitors, dicrotophos and phosphamidon.     

Comparative ester hydrolysis of carbaryl and ethiofencarb in four mammalian species

The comparative ester hydrolysis and selective toxicity of carbamate insecticides were studied in four mammalian species. Hydrolysis rates of carbaryl and ethiofencarb (Croneton) were examined in the rat, mouse, guinea pig, and gerbil. Respiratory ¹⁴CO₂ resulting from the hydrolysis of orally administered [carbonyl-¹⁴C]carbamates (0.2 mg/kg) was taken as measure of in vivo hydrolytic capabilities. Ester hydrolysis was found to be greater for ethiofencarb than for carbaryl in all species tested, although the relative order of hydrolysis among species was the same with both compounds. After 24 hr, gerbils had hydrolyzed 91% of the ethiofencarb and 65% of the carbaryl. Guinea pigs hydrolyzed somewhat less of the compounds, 65 and 58%, but considerably more than rats and mice, about 40 and 25%. Comparing hydrolysis capabilities to acute toxicity data revealed that those species exhibiting the greatest hydrolysis were equally or more susceptible to carbamate poisoning than those having lesser hydrolytic capabilities. While ester hydrolysis destroys the anticholinesterase activity of carbamates, it is clear from these findings that factors other than hydrolysis are largely responsible for the variation in toxicity of the carbamates to different mammalian species.     

The in vitro degradation of [14C]malathion by enzymatic extracts from resistant and susceptible strains of Drosophila melanogaster

Enzyme preparations from Drosophila melanogaster flies degraded [¹⁴C]malathion to α- and β-malathion monoacids and, hence, were considered to contain malathion carboxylesterase (ME) activity. Although ME- activity was stable during preincubation in the absence of malathion, it decreased dramatically during the course of the reaction, and could not be completely recovered by Sephadex G-25 chromatography. Furthermore, the protein fraction after chromatography still contained ¹⁴C, suggesting that the enzyme had become inhibited by a bound, ¹⁴C-labeled derivative. Extracts from a resistant (malathion-selected), an intermediate control, and the susceptible Canton S strains of D. melanogaster differed in the lability of ME activity during the reaction. This difference was partly attributed to the production of small amounts of malaoxon (2–8%) by the extracts from the more resistant strains. No consistent strain differences were found when the rate of malathion degradation was measured during the first minute of reaction, either with or without a microsomal oxidase inhibitor (metyrapone) present. These results, together with the cross-resistance of the malathion-selected strain to other insecticides and the lack of a synergistic effect of two carboxylesterase inhibitors (triphenyl phosphate and S,S,S-tributylphosphorotrithioate) suggested that malathion carboxylesterase does not contribute significantly to the observed differences in malathion resistance between strains.     

Sublethal effects of nine insecticides on Drosophila suzukii and its major pupal parasitoid Trichopria drosophilae

Background

Although the pupal parasitoid Trichopria drosophilae is used in conservative and augmentative biocontrol of Drosophila suzukii infestations, current pest management strategies mostly rely on multiple insecticide applications. In this context, the aim of the study was to investigate the baseline toxicity of nine insecticides on D. suzukii larvae and their multiple sublethal effects (LC₁₀) on immature stages of the pest feeding on contaminated diet and T. drosophilae developing within the intoxicated host.

Results

Chlorpyriphos and azadirachtin showed the lowest and the highest LC₁₀, the values of which were 9.78 × 10¹³ and 1.46 × 10³ times lower than their recommended label field rate, respectively. Among tested insecticides, imidacloprid, malathion and dimethoate were the only treatments that did not affect the juvenile development time of D. suzukii, while spinosad and the organophosphates chlorpyriphos and dimethoate did not influence fly pupal size. No sublethal effects were recorded on T. drosophilae degree of infestation (DI) and juvenile development time. On the contrary, cyazypyr and dimethoate negatively affected the success of parasitism (SP) and the number of progeny of the pupal parasitoid, in association with malathion for the first parameter and spinosad for the fertility. Compared to the untreated control, more female progeny emerged following azadirachtin exposure, while dimethoate caused the opposite effect. Imidacloprid, lambda-cyhalothrin and spinetoram decreased hind tibia length of emerged parasitoids.

Conclusion

This study provides new insights on the (eco)toxicological profile of nine insecticides and new information needed to support the deployment of T. drosophilae in the field within the sustainable management techniques against D. suzukii. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Esterase-mediated malathion resistance in the human head louse, Pediculus capitis (Anoplura: Pediculidae)

Resistance in a dual malathion- and permethrin-resistant head louse strain (BR-HL) was studied. BR-HL was 3.6- and 3.7-fold more resistant to malathion and permethrin, respectively, compared to insecticide-susceptible EC-HL. S,S,S-Tributylphosphorotrithioate synergized malathion toxicity by 2.1-fold but not permethrin toxicity in BR-HL. Piperonyl butoxide did not synergize malathion or permethrin toxicity. Malathion carboxylesterase (MCE) activity was 13.3-fold and general esterase activity was 3.9-fold higher in BR-HL versus EC-HL. There were no significant differences in phosphotriesterase, glutathione S-transferase, and acetylcholinesterase activities between strains. There was no differential sensitivity in acetylcholinesterase inhibition by malaoxon. Esterases from BR-HL had higher affinities and hydrolysis efficiencies versus EC-HL using various naphthyl-substituted esters. Protein content of BR-HL females and males was 1.6- and 1.3-fold higher, respectively, versus EC-HL adults. Electrophoresis revealed two esterases with increased intensity and a unique esterase associated with BR-HL. Thus, increased MCE activity and over-expressed esterases appear to be involved in malathion resistance in the head louse.