棉铃虫抗甲氧虫酰肼种群对12种杀虫剂的交互抗性

利用室内筛选获得的甲氧虫酰肼中等抗性种群(R, 30.57倍)和敏感种群(S),采用浸叶法测定了棉铃虫对12种常用杀虫剂的交互抗性。结果表明抗性种群对虫酰肼产生了13.57倍的中等水平交互抗性;对茚虫威的抗性倍数为3.05倍,无明显交互抗性;而对辛硫磷、毒死蜱、灭多威、高效氯氰菊酯、溴氰菊酯、虫螨腈、虱螨脲、氟啶脲、氟铃脲和甲氨基阿维菌素苯甲酸盐的抗性倍数在0.50 ~2.36倍之间,无交互抗性。试验结果提示,在棉铃虫对甲氧虫酰肼的抗药性治理中,轮换使用与甲氧虫酰肼没有交互抗性的杀虫剂将可有效延缓其抗药性发展。     

虫酰肼对甜菜夜蛾生物活性研究

测定了虫酰肼(RH-5992)对甜菜夜蛾的生物活性。杀卵作用测定表明,在200 mg/L浓度下,虫酰肼对甜菜夜蛾1日龄卵有较强的毒杀作用;用浸叶法测定了虫酰肼对甜菜夜蛾不同龄期幼虫的生物活性,发现1、2龄幼虫对药剂的敏感性较高,3~5龄幼虫敏感性下降但之间差异不大;拒食活性测定表明虫酰肼能明显抑制甜菜夜蛾幼虫的生长,降低其取食量,在10 mg/kg浓度时,表现了较强的拒食活性,96 h后拒食率达到73%以上。研究了虫酰肼对甜菜夜蛾生长发育的影响,发现其可延缓甜菜夜蛾的生长,使幼虫历期、蛹历期增长,同时降低甜菜夜蛾的生育繁殖能力,使幼虫成活率、化蛹率、羽化率、卵孵化率都有所下降。     

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。     

广西不同甜菜夜蛾种群对杀虫剂的敏感性

应用室内浸叶法测定了广西3个甜菜夜蛾种群对杀虫剂的敏感性,结果表明,广西不同菜区甜菜夜蛾种群对杀虫剂的敏感性不同。柳江甜菜夜蛾种群对氟啶脲、溴虫腈和氟虫脲的敏感性最高,分别是南宁种群的3.06、5.90、5.17倍,是桂林种群的2.28、2.56、4.93倍;桂林甜菜夜蛾种群对虫酰肼和多杀菌素的敏感性最高,分别是柳江种群的3.82、10.62倍,是南宁种群的4.91、4.36倍;南宁甜菜夜蛾种群对毒死蜱的敏感性几乎与桂林种群一样,是柳江种群的2.80倍;广西3个甜菜夜蛾种群对氟虫腈、高效氯氰菊酯、阿维菌素和溴氰菊酯的敏感性均相当低,无法求出毒力回归方程。     

酶抑制剂与防治甜菜夜蛾和斜纹夜蛾杀虫剂的互作效应

采用点滴法比较了甲维盆、虫螨腈.茚虫威、虫酰肼、毒死蟀、灭多威对甜菜夜蛾和斜纹夜蛾3龄幼虫的室内毒力,以及酶抑制剂与防治甜菜夜蛾和斜纹夜蛾杀虫剂的互作效应.结果表明,甲维盐、虫螨腈、茚虫威对2种试虫毒力较高,LC50值介于0.69～16.32μg/g之间;虫酰肼对甜菜夜蛾毒力较高,LC50值为37.66μg/g毒死蜱对斜纹夜蛾毒力较高,LC50值为20.71μg/g.酶抑制剂PBO,TPP,DEM,SV1在甜菜夜蛾和斜纹夜蛾上对虫螨腈和茚虫威均表现为抑制作用,增效比在0.25～0.96之间;而这4种酶抑制剂在甜菜夜蛾上对甲维盐和虫酰肼以及在斜纹夜蛾上对甲维盐和毒死蟀表现为增效作用,除SV1在斜纹夜蛾上对毒死蜱增效倍数高达16.20外,其它组合增效倍数均介于1.22～4.20之间.     

甜菜夜蛾对昆虫生长调节剂类杀虫剂的敏感性测定

用浸叶法测定了7种昆虫生长调节剂类杀虫剂对山东甜菜夜蛾田间种群的敏感性。监测结果表明:不同甜菜夜蛾品系或种群对供试药剂的敏感性均存在明显差异。甜菜夜蛾敏感品系对供试药剂的敏感性倍数为甲氧酰肼∶氟啶脲∶虫酰肼∶氟铃脲∶氟虫脲∶抑食肼∶除虫脲为95.74∶0.13∶2.01∶3.49∶.23∶.11∶;泰安范镇、潍坊寿光及临沂罗庄田间种群对供试药剂的敏感性顺序与甜菜夜蛾敏感品系的敏感性顺序基本一致。与敏感品系相比,3个甜菜夜蛾田间种群对同一种供试药剂的敏感性均有不同程度的下降,其中对虫酰肼和氟啶脲的敏感性下降倍数达到3以上,表现出低水平抗药性。     

不同药剂对甜菜夜蛾幼虫毒力和田间应用效果研究

利用浸渍法分别测定虫螨腈等不同药剂对甜菜夜蛾3龄及5龄幼虫的毒力，结果表明：不同药剂对甜菜夜蛾幼虫的毒力存在明显差异，一些特异杀虫剂对甜菜夜蛾幼虫的毒力普遍高于试验用常规化学杀虫剂的毒力；同一药剂对不同龄期幼虫毒力的差异程度也不同，如虫螨腈、氟啶脲、氟铃脲、甲胺基阿维菌素、阿维菌素、虫酰肼等药剂对甜菜夜蛾3龄及5龄幼虫毒力的差异程度明显低于顺式氯氰菊酯、丙溴磷、灭多威等化学药剂。同时，作者还对12种药剂分别稀释1000倍对甜菜夜蛾5龄幼虫不同时间的毒力进行了观察，除常规化学农药出现中毒现象较快外，虫螨腈、甲胺基阿维菌素也表现较快中毒症状，田间药效试验进一步验证防治甜菜夜蛾宜选用虫螨腈、氟啶脲、氟铃脲、甲胺基阿维菌素、阿维菌素、虫酰肼等药剂。     

上海市甜菜夜蛾对虫螨腈的抗药性及风险评价

通过浸叶法监测了上海崇明、松江、奉贤及浦东新区4个地区甜菜夜蛾对虫螨腈的抗药性,并在室内抗性筛选的基础上,研究了甜菜夜蛾上海种群对虫螨腈的抗性现实遗传力。结果表明,上述4个地区甜菜夜蛾种群对虫螨腈均处于敏感至低水平抗性(RR为0.9～5.2倍)。田间药效与室内毒力测定结果显示趋势一致。虫螨腈连续筛选10代后,与起始种群相比,抗性下降30%,甜菜夜蛾对虫螨腈的抗性现实遗传力为-0.041 4。抗性筛选结果表明,甜菜夜蛾对虫螨腈产生抗性的风险较低。     

斜纹夜蛾对茚虫威的抗药性汰选及交互抗性测定

为评估茚虫威抗性风险,在室内进行了斜纹夜蛾对茚虫威的抗性选育和交互抗性测定。经过10代6次室内抗性选育,获得了斜纹夜蛾对茚虫威抗性种群,与选育前相比,斜纹夜蛾对茚虫威的敏感性降低了15.63倍。抗性风险评估结果表明,斜纹夜蛾具有对茚虫威产生高水平抗性的风险。交互抗性测定发现,辛硫磷、高效氯氰菊酯和氟虫腈对茚虫威抗性种群的LC50值分别是同源对照种群的1.53、2.42和1.53倍,溴虫腈和灭多威对茚虫威抗性种群的LC50值分别是同源对照种群的0.78和0.96倍,表明茚虫威抗性种群对这几种杀虫剂未产生交互抗性。     

甜菜夜蛾对氯虫苯甲酰胺抗性种群选育及鱼尼丁受体基因表达特征

为明确甜菜夜蛾Spodoptera exigua对氯虫苯甲酰胺的抗性发展及抗性种群中鱼尼丁受体(ryanodine receptor,RyR)基因的表达量变化,室内采用饲料混毒法进行甜菜夜蛾对氯虫苯甲酰胺的抗性选育,荧光定量PCR技术研究了抗性和敏感种群之间RyR基因mRNA表达量的差异。结果表明,室内选育31代后获得一个抗性倍数为105.60倍的甜菜夜蛾抗性种群,其mRNA表达量在甜菜夜蛾不同发育阶段及抗性种群和敏感种群之间均存在差异,以表达量最低的卵期作为对照,抗性种群中1龄幼虫表达量最高,是卵期的154.58倍;其次是雄性成虫,其表达量是卵期的101.51倍;2~5龄幼虫分别是卵期的59.56、35.35、72.99和19.84倍。抗性种群中1、2和4龄幼虫mRNA表达量分别是敏感种群的5.99、2.79和2.14倍,其余阶段低于敏感种群。表明甜菜夜蛾对氯虫苯甲酰胺的抗药性可能主要表现在幼虫阶段,RyR基因的表达量变化与氯虫苯甲酰胺诱导有关。     

西花蓟马抗甲氨基阿维菌素苯甲酸盐种群的交互抗性与生化抗性机制

为了解西花蓟马Frankliniella occidentalis(Pergande)对甲氨基阿维菌素苯甲酸盐的抗性风险,采用生物和生化测定方法研究了西花蓟马甲维盐抗性种群与其它杀虫剂的交互抗性和生化抗性机制。西花蓟马甲维盐抗性种群对阿维菌素有高水平交互抗性,抗性倍数为31.656,对啶虫脒有中等水平交互抗性,为12.182,对吡虫啉、溴虫腈、氯氟氰菊酯、毒死蜱和灭多威有低水平交互抗性,为5.517~8.568,而对多杀菌素无明显交互抗性。增效剂胡椒基丁醚(PBO)、马来酸二乙酯(DEM)、三丁基三硫磷酸酯(DEF)和磷酸三苯酯(TPP)对甲维盐抗性种群和田间种群均有显著增效作用。甲维盐抗性种群多功能氧化酶细胞色素P₄₅₀和b₅含量、O-脱甲基酶、谷胱甘肽S-转移酶和羧酸酯酶活性均显著提高,分别为敏感种群的3.89、3.61、5.32、4.42和1.30倍,表明多功能氧化酶、谷胱甘肽S-转移酶和羧酸酯酶等解毒代谢酶活性的提高是西花蓟马对甲维盐产生抗性的重要机制。     

Biochemical mechanisms conferring cross-resistance between tebufenozide and abamectin in Plutella xylostella

Experiments have been carried out to confirm the cross-resistance between abamectin and tebufenozide in Plutella xylostella and demonstrate its mechanism. The results showed that the resistant strain of P. xylostella selected by tebufenozide (RF 99.38) really showed high cross-resistance to abamectin (RF 29.25). When this strain was subjected to resistance decaying treatment, breeding without contacting any insecticides, and abamectin resistance selection for 20 generations, the former resulted in decrease of its resistance to both tebufenozide and abamectin to about one third of the original (RF 35.03 and 11.67, respectively), and the later enhanced its resistance to abamectin dramatically (RF 303.77), but not to tebufenozide(RF 50.04). PBO showed high synergism to abamectin (SR 2.11-12.23), and the synergism ratio positively related to the resistance level among different strains. Enzyme analysis also proved that the activity of cytochrome P450 monooxygenase (MFO) was notable enhanced in the strains resistant to both tebufenozide and abamectin (1.71- to 3.01-fold). Based on discussion, it was concluded that tebufenozide selection could resulted in significant cross-resistance of P. xylostella to abamectin. The major mechanism for the cross-resistance should be the enhancement of MFO activity. For resistance management, tebufenozide and abamectin would not recommend for rotational use.     

Cytochrome P450 monooxygenase-mediated permethrin resistance confers limited and larval specific cross-resistance in the southern house mosquito, Culex pipiens quinquefasciatus

The cytochrome P450-dependent monooxygenases (P450s) are an important enzymatic system that metabolizes xenobiotics (e.g., pesticides), as well as endogenous compounds (e.g., hormones). P450-mediated metabolism can result in detoxification of insecticides such as pyrethroids, or can be involved in the bioactivation and detoxification of insecticides such as organophosphates. We isolated (from the JPAL strain) a permethrin resistant strain (ISOP450) of Culex pipiens quinquefasciatus, having 1300-fold permethrin resistance using standard backcrossing procedures. ISOP450 is highly related to the susceptible lab strain (SLAB) and the high resistance to permethrin is due solely to P450-mediated detoxification. This is the first time in mosquitoes that P450 monooxygenase involvement in pyrethroid resistance has been isolated and studied without the confounding effects of kdr. Resistance in ISOP450 is incompletely dominant (D = +0.3), autosomally linked, and monofactorally inherited. It is expressed in the larvae, but not in adults. Cross-resistance to pyrethroids lacking a 3-phenoxybenzyl moiety (tetramethrin, fenfluthrin, bioallethrin, and bifenthrin) ranged from 1.5- to 12-fold. ISOP450 had only limited (6.6- and 11-fold) cross-resistance to 3-phenoxybenzyl pyrethroids with an α-cyano group (cypermethrin and deltamethrin, respectively). Examination of cross-resistance patterns to organophosphate insecticides in ISOP450 showed an 8-fold resistance to fenitrothion, while low, but significant, levels of negative cross-resistance were found for malathion (RR = 0.84), temephos (RR = 0.73), and methyl-parathion (RR = 0.55). The importance and uniqueness of this P450 mechanism in insecticide resistance is discussed.     

Fipronil resistance mechanisms in the rice stem borer, Chilo suppressalis Walker

Fipronil resistance mechanisms were studied between the laboratory susceptible strain and the selective field population of rice stem borer, Chilo suppressalis Walker in the laboratory. The borer population was collected from Wenzhou county, Zhejiang province. After five generations of selection, fipronil resistance ratio was 45.3-fold compared to the susceptible strain. Synergism experiments showed that the synergistic ratios of PBO, TPP and DEF on fipronil in susceptible and resistant strains of C. suppressalis were 7.55-, 1.93- and 2.91-fold, respectively, and DEM showed no obvious synergistic action on fipronil. Activities of carboxylesterase and microsomal-O-demethylase in the resistant strain were 1.89- and 1.36-fold higher that in susceptible strain, and no significant difference of glutathione-S-transferase activity was found between the resistant and susceptible strains. The K_m and V_max experiments also demonstrated that fipronil resistance of C. suppressalis was closely relative to the enhanced activities of carboxylesterase and microsomal-O-demethylase. Moreover, cross-resistance between fipronil and other conventional insecticides and the multiple resistant properties of the original Wenzhou’s population were also discussed.     

Triazophos resistance mechanisms in the rice stem borer (Chilo suppressalis Walker)

A field population of the rice stem borer (Chilo suppressalis Walker) with 203.3-fold resistance to triazophos was collected. After 8-generation of continuous selection with triazophos in laboratory, resistance increased to 787.2-fold, and at the same time, the resistance to isocarbophos and methamidophos was also enhanced by 1.9- and 1.4-fold, respectively, implying some cross-resistance between triazophos and these two organophosphate insecticides. Resistance to abamectin was slightly enhanced by triazophos selection, and fipronil and methomyl decreased. Synergism experiments in vivo with TPP, PBO, and DEM were performed to gain a potential indication of roles of detoxicating enzymes in triazophos resistance. The synergism results revealed that TPP (SR, 1.92) and PBO (SR 1.63) had significant synergistic effects on triazophos in resistant rice borers. While DEM (SR 0.83) showed no effects. Assays of enzyme activity in vitro demonstrated that the resistant strain had higher activity of esterase and microsomal O-demethylase than the susceptible strain (1.20- and 1.30-fold, respectively). For glutathione S-transferase activity, no difference was found between the resistant and the susceptible strain when DCNB was used as substrate. However, 1.28-fold higher activity was observed in the resistant strain when CDNB was used. These results showed that esterase and microsomal-O-demethylase play some roles in the resistance. Some iso-enzyme of glutathione S-transferase may involve in the resistance to other insecticides, for this resistant strain was selected from a field population with multiple resistance background. Acetylcholinesterase as the triazophos target was also compared. The results revealed significant differences between the resistant and susceptible strain. The V_max and K_m of the enzyme in resistant strain was only 32 and 65% that in the susceptible strain, respectively. Inhibition tests in vitro showed that I₅₀ of triazophos on AChE of the resistant strain was 2.52-fold higher. Therefore, insensitive AChE may also involved in triazophos resistance mechanism of rice stem borer.     

新疆MEAM1烟粉虱隐种对吡虫啉的抗性遗传力分析及交互抗性测定

采用Tabashnik的域性状指标分析了新疆MEAM1(Middle-East-Asia-Minor l)烟粉虱隐种对吡虫啉的抗性现实遗传力(h2)和不同致死率下的抗性发展速率,同时测定了抗性种群对不同类型杀虫剂的交互抗性。结果表明,在30%~50%较低的选择压力下,新疆MEAM1烟粉虱隐种连续汰选8代后,对吡虫啉的抗性上升28.01倍,抗性现实遗传力h2为0.429 7。假设田间种群现实遗传力为实验室筛选估算值的1/2,即h2=0.214 9,对新疆MEAM1烟粉虱隐种对吡虫啉的抗性发展速率估算结果表明:在药剂选择压力为50%~60%下,若使其对吡虫啉的抗性增长10倍,则需要生长10~8代;而在药剂选择压力为70%~90%下,若使其抗性增长10倍,则仅需要生长6~4代。表明新疆MEAM1烟粉虱隐种对吡虫啉产生抗性的风险很大。交互抗性测定结果显示:抗性种群对同类型的杀虫剂吡虫清和噻虫嗪分别产生了10.78倍和4.75倍的中等至低水平交互抗性;对多杀菌素、毒死蜱、吡丙醚和高效氯氰菊酯的敏感性有所降低;对阿维菌素、氟啶虫胺腈和乙基多杀菌素等杀虫剂则无交互抗性。     

Fitness cost, cross resistance and realized heritability of resistance to imidacloprid in Spodoptera litura (Lepidoptera: Noctuidae)

Imidacloprid has been used as a key insecticide for controlling sucking insect pests of cotton, whereas Spodoptera litura also has been indirectly exposed to this insecticide in Pakistan. To evaluate the risk of resistance evolution and to develop a better resistance management strategy, a field collected population was selected with imidacloprid in the laboratory. Thereafter, fitness cost, realized heritability and cross resistance of imidacloprid resistance in S. litura were investigated. After 14 generations of selection with imidacloprid, S. litura developed a 137.48-fold resistance to the insecticide. Bioassay revealed that this strain showed cross-resistance to acetamiprid (RR 8.52) and a little to lamdacyhalothrin (1.92) but negative cross-resistance was found to methomyl (−0.19). The resistant strain had a relative fitness of 0.38, with substantially lower rates of larval survival, larval duration, male pupal duration, development time, emergence rate of healthy adults, fecundity, hatchability, and prolonged larval and pupal duration. Mean relative growth rate of the larvae, intrinsic rate of population increase, and biotic potential was lower for the selected populations. The estimated realized heritability (h²) of imidacloprid resistance was 0.15 in the resistant strain of S. litura. Development of the resistance may cost significant fitness for the resistant population. This study provided valuable information for further understanding the impact of imidacloprid resistance on physiological parameters of S. litura and for facilitating the development of resistance management strategies.     

Effects of mutations in Drosophila nicotinic acetylcholine receptor subunits on sensitivity to insecticides targeting nicotinic acetylcholine receptors

Several strains of Drosophila melanogaster possess mutant alleles in nicotinic acetylcholine receptor (nAChR) subunits, Dα1 and Dβ2 that confer resistance to neonicotinoids such as imidacloprid and nitenpyram, and Dα6, that confers resistance to spinosyns. These mutant strains were bioassayed with a selected set of nAChR active insecticides including neonicotinoids, spinosad, and sulfoxaflor, a new sulfoximine insecticide. All of the neonicotinoids examined, except dinotefuran showed reduced insecticidal efficacy on larvae of the Dα1 mutant, suggesting that this subunit may be important in the action of these insecticides. All of the neonicotinoids, including dinotefuran, showed reduced insecticidal efficacy on larvae possessing the Dβ2 mutation. A similar pattern of broad neonicotinoid resistance to that of Dβ2 alone was also observed for larvae with both the mutations (Dα1 + Dβ2). The Dβ2 mutation exhibited a lower level of cross-resistance to sulfoxaflor (<3-fold) than to any of the neonicotinoids (>13-fold). In contrast, there was no cross-resistance for any of the neonicotinoids or sulfoxaflor in adult flies with the Dα6 mutation, which confers high levels of resistance to spinosad. Thus in the D. melanogaster strains studied, target site resistance observed for the neonicotinoids and the spinosyns does not translate directly to resistance towards sulfoxaflor.     

Fipronil resistance mechanisms in the rice stem borer,Chilo suppressalis Walker

Fipronil resistance mechanisms were studied between the laboratory susceptible strain and the selective field population of rice stem borer, Chilo suppressalis Walker in the laboratory. The borer population was collected from Wenzhou county, Zhejiang province. After five generations of selection, fipronil resistance ratio was 45.3-fold compared to the susceptible strain. Synergism experiments showed that the synergistic ratios of PBO, TPP and DEF on fipronil in susceptible and resistant strains of C. suppressalis were 7.55-, 1.93- and 2.91-fold, respectively, and DEM showed no obvious synergistic action on fipronil. Activities of carboxylesterase and microsomal-O-demethylase in the resistant strain were 1.89- and 1.36-fold higher that in susceptible strain, and no significant difference of glutathione-S-transferase activity was found between the resistant and susceptible strains. The K_m and V_max experiments also demonstrated that fipronil resistance of C. suppressalis was closely relative to the enhanced activities of carboxylesterase and microsomal-O-demethylase. Moreover, cross-resistance between fipronil and other conventional insecticides and the multiple resistant properties of the original Wenzhou’s population were also discussed.