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。     

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。     

小菜蛾对唑虫酰胺的抗性监测、抗性生化机制及交互抗性

为了明确小菜蛾Plutella xylostella对唑虫酰胺的抗性特征,采用生物生化方法测定了江西省5个蔬菜产区小菜蛾田间种群对唑虫酰胺的抗性水平,并研究了小菜蛾唑虫酰胺抗性品系对其它药剂的交互抗性和生化抗性机制。结果显示,分宜县和高安市小菜蛾田间种群对唑虫酰胺尚未产生明显抗性,永丰县、德安县和余江县小菜蛾种群对唑虫酰胺产生了低水平的抗性,抗性倍数为5.20~8.20倍;小菜蛾唑虫酰胺抗性品系对阿维菌素、氯虫苯甲酰胺、氟虫双酰胺和茚虫威有中低水平的交互抗性,抗性倍数分别为11.72、3.44、2.77和2.20倍,而对溴虫腈、定虫隆和丁醚脲无交互抗性;增效剂磷酸三苯酯和胡椒基丁醚对小菜蛾唑虫酰胺抗性品系均有显著增效作用,增效倍数分别为3.42倍和2.64倍;唑虫酰胺抗性品系的酯酶和多功能氧化酶活性均显著提高,分别为敏感品系的2.18倍和1.64倍。研究表明,小菜蛾对唑虫酰胺产生抗性可能与酯酶和多功能氧化酶活性的升高有关。     

褐飞虱对氟啶虫胺腈的抗性监测与生化抗性机制

为明确我国褐飞虱田间种群对氟啶虫胺腈的抗性现状及生化抗性机制,2017年-2019年采用稻茎浸渍法测定了采集自7省共13个褐飞虱田间种群对氟啶虫胺腈的抗性,并研究了氟啶虫胺腈抗性种群与其他杀虫剂的交互抗性以及增效剂对氟啶虫胺腈的增效效果。结果表明：近3年来褐飞虱对氟啶虫胺腈产生了中等水平抗性(RR=10.3～30.9)。氟啶虫胺腈抗性品系对呋虫胺、噻虫嗪和烯啶虫胺分别产生了9.1倍、7.9倍和4.1倍的低水平交互抗性,与噻嗪酮、毒死蜱、吡蚜酮、三氟苯嘧啶和吡虫啉不存在交互抗性。增效剂PBO对氟啶虫胺腈抗性品系和浙江龙游19(Longyou-19)田间种群分别具有4.2倍和3.8倍的明显增效作用。综上,褐飞虱田间种群已对氟啶虫胺腈产生中等水平抗性。多功能氧化酶参与了褐飞虱对氟啶虫胺腈的代谢抗性。     

华东4地区灰飞虱对8种杀虫剂的抗性监测

为明确2021—2022年华东4地区灰飞虱田间种群对常用杀虫剂的抗性现状及抗性机理，采用稻苗浸渍法分别测定了江苏仪征、盐城，浙江长兴和安徽庐江4地区灰飞虱田间种群对8种杀虫剂的抗性水平，并测定了3种解毒酶抑制剂增效醚(PBO)、顺丁烯二酸二乙酯(DEM)和磷酸三苯酯(TPP)对噻嗪酮防治灰飞虱的增效作用。结果表明：4个灰飞虱田间种群对噻嗪酮产生了中等至高水平抗性(抗性倍数RR=61.5～148.8)；对毒死蜱产生了中等水平抗性(RR=14.9～28.3)；对烯啶虫胺(RR=0.7～9.9)、噻虫嗪(RR=1.6～8.3)、呋虫胺(RR=2.9～10.0)和氟啶虫胺腈(RR=2.5～8.7)处于敏感至低水平抗性；对吡蚜酮(RR=1.0～5.0)和三氟苯嘧啶(RR=0.5～2.3)均仍处于敏感水平。增效试验结果显示，3种解毒酶抑制剂对噻嗪酮均无显著增效作用，表明3种解毒酶可能不参与灰飞虱对噻嗪酮的抗性。研究结果可为灰飞虱的田间抗性治理提供科学指导。     

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。     

广西不同地区稻纵卷叶螟对4种杀虫剂的抗药性研究

采用浸叶胃毒法测定了稻纵卷叶螟2龄幼虫对氯虫苯甲酰胺等5种杀虫剂的毒力和抗药性,结果表明,毒力大小依次为阿维菌素＞氟虫双酰胺＞氯虫苯甲酰胺＞氯虫·噻虫嗪;玉林市和合浦县稻纵卷叶螟种群对氟虫双酰胺和氯虫苯甲酰胺敏感性降低,玉林市种群对氟虫双酰胺具有低水平抗性,LC50为0.1925 mg/L,相对抗性倍数达到5.94.来宾、防城和南宁市种群对氯虫·噻虫嗪敏感性降低,横县、永福、兴安和合浦县种群对40％氯虫·噻虫嗪具有低水平抗性,其中以合浦县种群抗性最高,相对抗性倍数达到6.37,LC50为0.3171 mg/L.     

棉铃虫对溴氰菊酯、三氟氯氰菊酯及其复配剂的抗性趋势与交互抗性

在70％的高选择压下,分别用溴氰菊酯、三氟氯氰菊酯和凯明2号(50％辛硫磷·甲基对硫磷·三氟氯氰乳油,即含三氟氯氰菊酯的复配药剂)对室内饲养了12代未经农药处理的棉铃虫Helicoverpa armigera(H(?)bner)敏感品系进行了抗性筛选。结果,经连续筛选至第12代的LD_(50)值与筛选前第1代的LD_(50)值比较,抗溴氰菊酯种群对溴氰菊酯的抗性为136.7倍,属高抗水平;抗三氟氯氰菊酯种群对三氟氯氰菊酯的抗性为9.5倍,抗凯明2号种群对凯明2号的抗性为3.4倍,均属低抗水平。用8种常用杀虫剂分别对这3个种群在停止上述杀虫剂筛选2代后进行了交互抗性分析。结果表明,3个种群平均对8种杀虫剂的抗性倍数中,对溴氰菊酯、氰戊菊酯、灭多威的抗性极显著高于其余5种杀虫剂;3个种群的平均抗性倍数之间差异极显著,顺序依次为抗溴氰菊酯种群>抗三氟氯氰菊酯种群>抗凯明2号种群;以平均抗性倍数表示的抗性种群与杀虫剂的交互作用有以下几个结果:①高抗溴氰菊酯的种群对氰戊菊酯和灭多威有极显著的交互抗性,但对三氟氯氰菊酯和凯明2号仍反应敏感。②抗三氟氯氰菊酯和抗凯明2号的2个种群对溴氰菊酯有极显著的交互抗性;抗三氟氯氰菊酯种群对灭多威和氰戊菊酯有一定抗性,抗凯明2号种群对硫丹有一定抗性。     

草地贪夜蛾对甲氨基阿维菌素苯甲酸盐和虱螨脲的抗性风险评估

甲氨基阿维菌素苯甲酸盐(甲维盐)和虱螨脲是目前生产上防治草地贪夜蛾的主要杀虫剂,为评估其抗性风险,以福建省草地贪夜蛾田间种群为研究对象,在实验室抗性汰选品系选育基础上,采用数量遗传学域性状分析法并结合交互抗性测定,进行草地贪夜蛾对上述两种杀虫剂的抗性风险评估。结果表明：非连续汰选11代和10代后,草地贪夜蛾对甲维盐(F₁₁)和虱螨脲(F₁₀)的抗性倍数分别达30.57倍和11.35倍;抗性现实遗传力分别为0.403和0.555,且前半段筛选的抗性遗传力都远大于后半段;药剂在室内对草地贪夜蛾致死率为50%～90%时,对甲维盐和虱螨脲抗性倍数上升10倍需要汰选8～15代和6～12代。交互抗性测定显示,甲维盐汰选品系对氯虫苯甲酰胺、虱螨脲、虫螨腈无交互抗性,对茚虫威和乙基多杀菌素存在一定交互抗性。虱螨脲汰选品系对氯虫苯甲酰胺、甲维盐、茚虫威、虫螨腈和乙基多杀菌素均无交互抗性。结果表明：草地贪夜蛾对甲维盐和虱螨脲存在快速产生抗性的风险,但可通过与无交互抗性药剂轮用来延缓抗性发展。     

中国水稻主产区褐飞虱对3种杀虫剂的抗性监测

2006-2009年,用稻茎浸渍法连续监测了广西南宁市、广东阳江市、湖南东安县、福建福清市、江西上高县、湖北孝感市、浙江金华市、江苏通州市和安徽和县共9个地区褐飞虱种群对吡虫啉、噻嗪酮和氟虫腈的抗性变化。结果表明:褐飞虱种群对吡虫啉的抗性仍处于高水平至极高水平抗性阶段(105.5~459.7倍),但2009年监测到东安、孝感、上高种群对吡虫啉的抗性已有下降趋势;褐飞虱种群对氟虫腈的抗性有增长趋势,2006到2009年褐飞虱种群对氟虫腈由敏感至低水平抗性(<6.9倍)发展到了中水平至高水平抗性(13.5~43.3倍);由于2005年吡虫啉在高抗地区的禁用,褐飞虱种群对噻嗪酮的抗性上升速度加快,2009年已处于低水平至中水平抗性阶段(7.0~14.4倍)。这表明在吡虫啉、氟虫腈被禁用后,大面积单一使用噻嗪酮进行防治,褐飞虱对噻嗪酮的抗性有可能加速发展。     

天津市烟粉虱隐种鉴定及其携带TYLCV、内共生菌情况和抗药性监测

为明确天津市烟粉虱Bemisia tabaci隐种的类别及其寄主适应性、传毒能力、携带内共生菌情况和抗药性,采用mt COI酶切法对从武清、西青、蓟州和宁河4个区的番茄、黄瓜及辣椒3种寄主上采集的12个烟粉虱种群进行隐种鉴定,采用PCR检测其携带番茄黄化曲叶病毒（tomato yellow leaf curl virus,TYLCV）和内共生菌情况,并采用浸叶法测定其对4种常用药剂的抗性。结果表明,采集的烟粉虱种群以MED隐种为主,占所有检测个体的93.33%,有3个种群为MED和MEAM1隐种混合发生。所有检测个体中有36.25%的个体携带TYLCV,在6个种群中检测到TYLCV,其中5个种群有超过50%的个体携带TYLCV。在12个种群中共检测到Hamiltonella、立克次氏体Rickettsia、Cardinium和杀雄菌属Arsenophnus共4种内共生菌,携带个体比例分别为90.63%、48.96%、43.75%和8.33%,进一步对内共生菌协同感染情况进行分析,发现有HARC、HRC、HAC、HR、HC和AC共6个协同感染型,感染率分别为4.17%、28.13%、3....     

Insecticide resistance management of Bemisia tabaci (Hemiptera: Aleyrodidae) in Australian cotton – pyriproxyfen,spirotetramat and buprofezin

BACKGROUND

Bemisia tabaci is a globally significant agricultural pest including in Australia, where it exhibits resistance to numerous insecticides. With a recent label change, buprofezin (group 16), is now used for whitefly management in Australia. This study investigated resistance to pyriproxyfen (group 7C), spirotetramat (group 23) and buprofezin using bioassays and available molecular markers.

RESULTS

Bioassay and selection testing of B. tabaci populations detected resistance to pyriproxyfen with resistance ratios ranging from 4.1 to 56. Resistance to spirotetramat was detected using bioassay, selection testing and sequencing techniques. In populations collected from cotton, the A2083V mutation was detected in three populations of 85 tested, at frequencies ≤4.1%, whereas in limited surveillance of populations from an intensive horticultural region the frequency was ≥75.8%. The baseline susceptibility of B. tabaci to buprofezin was determined from populations tested from 2019 to 2020, in which LC₅₀ values ranged from 0.61 to 10.75 mg L⁻¹. From the bioassay data, a discriminating dose of 200 mg L⁻¹ was developed. Recent surveillance of 16 populations detected no evidence of resistance with 100% mortality recorded at doses ≤32 mg L⁻¹. A cross-resistance study found no conclusive evidence of resistance to buprofezin in populations with high resistance to pyriproxyfen or spirotetramat.

CONCLUSIONS

In Australian cotton, B. tabaci pest management is challenged by ongoing resistance to pyriproxyfen, while resistance to spirotetramat is an emerging issue. The addition of buprofezin provides a new mode-of-action for whitefly pest management, which will strengthen the existing insecticide resistance management strategy. © 2023 Commonwealth of Australia. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Baseline susceptibilities of B- and Q-biotype Bemisia tabaci to anthranilic diamides in Arizona

BACKGROUND: Development of pyriproxyfen and neonicotinoid resistance in the B-biotype whitefly and recent introduction of the Q biotype have the potential to threaten current whitefly management programs in Arizona. The possibility of integrating the novel anthranilic diamides chlorantraniliprole and cyantraniliprole into the current program to tackle these threats largely depends on whether these compounds have cross-resistance with pyriproxyfen and neonicotinoids in whiteflies. To address this question, the authors bioassayed a susceptible B-biotype strain, a pyriproxyfen-resistant B-biotype strain, four multiply resistant Q-biotype strains and 16 B-biotype field populations from Arizona with a systemic uptake bioassay developed in the present study. RESULTS: The magnitude of variations in LC₅₀ and LC₉₉ among the B-biotype populations or the Q-biotype strains was less than fivefold and tenfold, respectively, for both chlorantraniliprole and cyantraniliprole. The Q-biotype strains were relatively more tolerant than the B-biotype populations. No correlations were observed between the LC₅₀ (or LC₉₉) values of the two diamides against the B- and Q-biotype populations tested and their survival rates at a discriminating dose of pyriproxyfen or imidacloprid. CONCLUSION: These results indicate the absence of cross-resistance between the two anthranilic diamides and the currently used neonicotinoids and pyriproxyfen. Future variation in susceptibility of field populations to chlorantraniliprole and cyantraniliprole could be documented according to the baseline susceptibility range of the populations tested in this study. Copyright © 2011 Society of Chemical Industry     

Effect of milbemectin on the sweetpotato whitefly,Bemisia tabad

Milbemectin has a chemical structure close to the group of avermectins, which are derived fromStreptomyces avermitilis, and is considered primarily an efficient miticide. Effects of milbemectin on the sweetpotato whitefly,Bemisia tabaci Gennadius, were investigated under laboratory and field conditions. In bioassays conducted under controlled chamber conditions, the compound affected 1st instars ofB. tabaci, resulting in a LC₉₀ of 0.06 mg a.i. I-1. Later stage larvae were much less affected. Milbemectin is highly photodegradable in sunlight. In laboratory assays, when treated cotton seedlings were subjected to 3 h of sunlight before being exposed toB. tabaci adults, no mortality of the whiteflies was observed. Milbemectin at a concentration of 2 mg a.i. I-1 applied in combination with 0.2% ‘Ultra Fine’ mineral oil showed a residual activity of 67% adult mortality 10 days after application, whereas milbemectin alone had no appreciable activity. The effect of milbemectin on whitefly populations in a cotton field was compared with that of cypermethrin and of untreated control. Although milbemectin was not applied with mineral oil, it was more effective than cypermethrin in controlling the whitefly populations. This insecticide/miticide seems not to affect appreciably natural enemies ofB. tabaci. Milbemectin may be considered a compound with the potential for controllingB. tabaci populations. Mineral oils enhanced the potency of milbemectin on both whitefly larvae and adults. http://www.phytoparasitica.org posting July 27, 1999. Contribution No. 501/99 from the Inst. of Plant Protection, Agricultural Research Organization.     

Selection for imidacloprid resistance in silverleaf whiteflies from the Imperial Valley and development of a hydroponic bioassay for resistance monitoring

A field-collected population of the silverleaf whitefly, Bemisia argentifolii, was selected with the nicotinyl compound, imidacloprid, over 32 generations to determine if resistance would develop when maintained under continuous selection pressure in a greenhouse. Resistance was slow to increase at first with low to moderate levels of resistance (RR from 6- to 17-fold) in the first 15 generations of selection. Further selection steadily led to higher levels of resistance, with the greatest resistance ratio at 82-fold, the gradual rise suggesting the involvement of a polygenic system. At the end of the selection, slopes of probit regressions were substantially steeper than earlier, indicating increased homogeneity of imidacloprid resistance in this strain. A hydroponic bioassay featuring systemic uptake of imidacloprid through roots was developed to monitor the changes in resistance to imidacloprid in the selected whitefly strain and in seven field-collected strains from Imperial Valley, California. Six out of seven field-collected strains exhibited low LC₅₀ values (0·002 to 0·512 mg ml^-1) compared to the selected resistant strain, with one exception where the LC₅₀ was 0·926 mg ml^-1 (RR=15·0). Variation in responses to imidacloprid in the field strains suggest that this technique is sufficiently sensitive to detect differences in susceptibilities of whitefly populations. The imidacloprid-resistant strain showed no cross-resistance to endosulfan, chlorpyrifos or methomyl (RR ranging from 0·4- to 1·5-fold). A low level of cross-resistance was observed to bifenthrin in the IM-R strain at 7-fold. The success of selection for resistance to imidacloprid has serious implications for whitefly control programs that rely heavily on imidacloprid. ©1997 SCI     

Pyriproxyfen,a novel insect growth regulator for controlling whiteflies: Mechanisms and resistance management

Pyriproxyfen, a novel juvenile hormone mimic, is a potent suppressor of embryogenesis and adult formation of the sweetpotato whitefly, Bemisia tabaci (Gennadius), and the greenhouse whitefly, Trialeurodes vaporariorum (Westwood). Dipping of cotton or tomato seedlings infested with 0 to 1-day-old eggs in 0.1 mg litre^?1 resulted in over 90% suppression of egg hatch of both B. tabaci and T. vaporariorum. Older eggs were affected to a lesser extent. Exposure of whitefly females to cotton or tomato seedlings treated with pyriproxyfen resulted in oviposition of non-viable eggs. The LC90 values for egg viability of B. tabaci and T. vaporariorum exposed to treated plants were 0.05 and 0.2 mg litre^?1, respectively. Treatment of whitefly larvae with 0.04–5 mg litre^?1 resulted in normal development until the pupal stage; however, adult emergence was totally suppressed. Second instars of B. tabaci exposed to 5 mg litre^?1 pyriproxyfen, excreted honeydew at a level similar to the control level until the fourth instar (pupation), after which a strong reduction was observed. Inhibition of egg-hatch on the lower surface of cotton leaves was observed when their upper surface was treated with 1–25 mg litre^?1, indicating a pronounced translaminar effect. These findings indicate that pyriproxyfen is an efficient control agent of both B. tabaci and T. vaporariorum. The compound has been used successfully for controlling whiteflies in Israeli cotton fields since 1991. Adults of B. tabaci collected from a rose greenhouse and from adjacent cotton fields were monitored during 1991–1993 for their susceptibility to pyriproxyfen. A high level of resistance was recorded in whiteflies collected from a greenhouse after three successive applications of pyriproxyfen. Based on LC50 values, the resistance ratio for egg-hatch suppression was 554-fold and, for adult emergence failure, 10-fold. However, a single treatment of pyriproxyfen in cotton fields during the summer season (according to an insecticide resistance management (IRM) strategy) did not alter appreciably the susceptibility of B. tabaci to this compound. In order to prevent development of resistance, an attempt should be made to restrict its use to one treatment per crop season applied during the peak activity of the pest. Pyriproxyfen can be alternated with other novel compounds such as buprofezin and diafenthiuron for controlling whiteflies in cotton, vegetables and ornamentals as part of integrated pest management (IPM) and IRM strategies. In pyriproxyfen- or buprofezin-resistant strains of B. tabaci or T. vaporariorum, no appreciable cross-resistance was observed among pyriproxyfen, buprofezin and diafenthiuron.     

21种化学药剂对新疆棉田主要害虫毒力及对多异瓢虫的安全性

为明确现阶段棉田常用化学杀虫剂对新疆维吾尔自治区（简称新疆）棉花主要害虫的毒力以及对新疆本地优势天敌多异瓢虫Hippodamia variegata的安全性,于室内分别测定当前21种棉田常用化学药剂对新疆棉田3种主要害虫棉蚜Aphis gossypii、截形叶螨Etranychus truncatus和棉铃虫Helicoverpa armigera以及优势天敌多异瓢虫的毒力,比较不同药剂对各种害虫和天敌的相对毒力指数以及益害毒性比。结果表明,药剂处理24 h后,10种蚜虫防治药剂对棉蚜成蚜的半致死浓度LC₅₀由高到低依次为氟啶虫胺腈、啶虫脒、吡虫啉、环氧虫啶、噻虫嗪、丁硫克百威、烯啶虫胺、呋虫胺、螺虫乙酯和吡蚜酮,其中益害毒性比较高的药剂主要有氟啶虫胺腈和螺虫乙酯;5种叶螨防治药剂对截形叶螨成螨的LC₅₀从高到低依次为阿维菌素、哒螨灵、四螨嗪、噻螨酮和炔螨特,其中益害毒性比较高的药剂主要有四螨嗪、噻螨酮和阿维菌素;6种鳞翅目害虫幼虫防治药剂对棉铃虫3龄幼虫的LC₅₀由高到低顺次为甲氨基阿维菌素苯甲酸盐（简称甲维盐）、氯虫苯甲酰胺、茚虫威、灭多威、毒死蜱和高效氯氰菊酯,其中益害毒性比较高的药剂主要有甲维盐和氯虫苯甲酰胺。综合上述2个方面结果,氟啶虫胺腈、阿维菌素、甲维盐和氯虫苯甲酰胺不仅对棉花害虫毒力效果强,而且对有益天敌安全性高。     

Monitoring of resistance to spirodiclofen and five other acaricides in Panonychus citri collected from Chinese citrus orchards

BACKGROUND: Citrus red mite, Panonychus citri (McGregor), is one of the most important pesticide‐resistant pests in China. In order better to understand its resistance status, six populations of the mite were collected from Chinese citrus orchards for monitoring of resistance to spirodiclofen and another five acaricides. RESULTS: All the samples collected in the field in 2006 were susceptible to spirodiclofen. However, the LC₅₀ values in populations sampled in 2009 ranged from 3.29 to 418.24 mg L^?1 spirodiclofen, a 127‐fold difference between the least and most sensitive populations. Compared with a susceptible strain, 50‐fold and 90.8‐fold resistance to spirodiclofen was detected in populations sampled from Pinghe and Fuzhou in 2009, as well as cross‐resistance to spirotetramat. The LC₅₀ values for abamectin, fenpropathrin, hexythiazox and pyridaben in the collected samples ranged from 0.041 to 3.52 mg L^?1, from 23.91 to 696.16 mg L^?1, from 13.94 to 334.19 mg L^?1 and from 48.90 to 609.91 mg L^?1 respectively. CONCLUSION: Great variations in resistance to the tested acaricides were observed among the sampled populations. The Pinghe population developed resistance to all the acaricides tested. The Jianning population was susceptible to most acaricides tested, except pyridaben. Resistance management strategies were conducted on the basis of these observations. Copyright © 2010 Society of Chemical Industry