Susceptibility to thiamethoxam of Musca domestica from Danish livestock farms

BACKGROUND: Neonicotinoid baits are currently replacing anticholinesterase baits for control of adult houseflies (Musca domestica L.). Introduction of new insecticides includes evaluation of their cross-resistance potential, which was assessed for thiamethoxam in field populations from Denmark. RESULTS: In feeding bioassay with a susceptible strain, thiamethoxam LC(50) at 72 h was 1.7 microg thiamethoxam g(-1) sugar, making it 19-fold, 11-fold and threefold more toxic to houseflies than azamethiphos, methomyl and spinosad respectively. The field populations were 6-76-fold resistant to thiamethoxam. There was no correlation between the toxicities of thiamethoxam and spinosad, dimethoate, methomyl, bioresmethrin or azamethiphos. The toxicity in feeding bioassay at 72 h of imidacloprid in a susceptible strain was 32 microg imidacloprid g(-1) sugar at LC(50), making it 19-fold less toxic to houseflies than thiamethoxam. There was a strong significant correlation between the toxicities of thiamethoxam and imidacloprid in field populations.CONCLUSION: Neonicotinoid-resistant houseflies were present at a detectable and noticeable level before thiamethoxam and imidacloprid were introduced for housefly control in Denmark. The toxicity of thiamethoxam is explained by other parameters than the toxicities of spinosad, dimethoate, methomyl, bioresmethrin or azamethiphos. The cross-resistance between thiamethoxam and imidacloprid indicates a coincidence of mechanism of the toxicity and resistance in the field populations.     

Spinosad resistance in female Musca domestica L. from a field-derived population

BACKGROUND: Bait-formulated spinosad is currently being introduced for housefly (Musca domestica L.) control around the world. Spinosad resistance was evaluated in a multiresistant field population and strains derived from this by selection with insecticides. Constitutive and spinosad-induced expression levels of three cytochrome P450 genes, CYP6A1, CYP6D1 and CYP6D3, previously reported to be involved in insecticide resistance, were examined. RESULTS: In 2004 a baseline for spinosad toxicity of Danish houseflies where all field populations were considered to be susceptible was established. In the present study, females of a multiresistant field population 791a were, however, 27-fold spinosad resistant at LC₅₀, whereas 791a male houseflies were susceptible. Strain 791a was selected with spinosad, thiamethoxam, fipronil and imidacloprid, resulting in four strains with individual characteristics. Selection of 791a with spinosad did not alter spinosad resistance in either males or females, but counterselected against resistance to the insecticides thiamethoxam and imidacloprid targeting nicotinic acetylcholine receptors. A synergist study with piperonyl butoxide, as well as gene expression studies of CYP6A1, CYP6D1 and CYP6D3, indicated a partial involvement of cytochrome P450 genes in spinosad resistance. CONCLUSION: This study reports female-linked spinosad resistance in Danish houseflies. Negative cross-resistance was observed between spinosad and neonicotinoids in one multiresistant housefly strain. Spinosad resistance involved alterations of cytochrome P450 gene expression. Copyright © 2011 Society of Chemical Industry     

Resistance to spinosad in the western flower thrips, Frankliniella occidentalis (Pergande), in greenhouses of south-eastern Spain

Susceptibility to spinosad of western flower thrips (WFT), Frankliniella occidentalis (Pergande), from south-eastern Spain was determined. LC(50) values of the field populations without previous exposure to spinosad collected in Murcia in 2001 and 2002 ranged from 0.005 to 0.077 mg L(-1). The populations collected in Almeria in 2003 in greenhouses were resistant to spinosad (LC(50) > 54 mg L(-1)) compared with the authors' highly susceptible laboratory strain. The highly sensitive laboratory strain leads to very high resistance ratios for the field populations (>13 500), but these ratios do not necessarily mean resistance problems and control failures (spinosad field rate 90-120 mg L(-1)). The populations collected in Murcia from some greenhouses in 2004 were also resistant to spinosad (RF > 3682). Spinosad overuse, with more than ten applications per crop, produced these resistant populations in some greenhouses. Spinosad showed no cross-resistance to acrinathrin, formetanate or methiocarb in laboratory strains selected for resistance towards each insecticide. Correlation analysis indicated no cross-resistance among spinosad and the other three insecticides in 13 field populations and in nine laboratory strains. The synergists piperonyl butoxide (PBO), S,S,S-tributyl phosphorotrithioate (DEF) and diethyl maleate (DEM) did not enhance the toxicity of spinosad to the resistant strains, indicating that metabolic-mediated detoxification was not responsible for the spinosad resistance. These findings suggest that rotation with spinosad may be an effective resistance management strategy.     

Assessing insecticide resistance and aversion to methomyl-treated toxic baits in Musca domestica L (Diptera: Muscidae) populations in southern California

Progeny of house flies (Musca domestica L) from ten California poultry operations, three dairies and one horse-riding facility were tested for methomyl- and muscalure-treated bait resistance using up to three different assays: a topical assay, a no-choice feeding assay and a choice feeding assay. LD50 resistance factors from the topical assay, compared with a locally-derived susceptible colony, ranged between 1 and 4. LC50 resistance factors from the no-choice feeding assay ranged mostly between 2 and 5, with one value of 18. Measurable LT50 resistance ratios for female flies in the choice feeding assay ranged from 43 to 159; two populations had <10% mortality at 48h and could not be measured. LT50 resistance ratios for male flies in the choice feeding assay ranged from 26 to 96, and one population was too resistant to measure. A behavioral assay tested the feeding preference of male and female flies provided a dish of sugar and a dish of methomyl- and muscalure-treated bait. Of eight strains tested, females from seven strains and males from six strains showed significant preference for sugar over bait. Behavioral factors appear to be important in the severe resistance of house flies to baits in California.     

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。     

Development of strategies for monitoring indoxacarb and gel bait susceptibility in the German cockroach (Blattodea: Blattellidae)

BACKGROUND: Advion^® cockroach gel bait (6 g kg^?1 indoxacarb) is in widespread use for Blattella germanica (L.) control in the United States. However, baseline susceptibility levels to indoxacarb in German cockroach field populations are not known. Hence, this research sought to develop monitoring strategies to estimate the susceptibility of German cockroach populations to indoxacarb. RESULTS: Four bioassays were evaluated: topical lethal dose (LD), formulated gel bait lethal time (LT), vial lethal concentration (LC) and gel bait matrix LD. Of these methods, the vial LC and gel bait matrix LD bioassays were the most economical and relevant assessment strategies. For indoxacarb susceptibility monitoring, a two‐tiered approach was developed that utilizes diagnostic concentrations and doses in vial LC (30 and 60 µg vial^?1) and gel bait matrix LD (1.0, 1.5 and 2.5 µg insect^?1) formats. CONCLUSIONS: A two‐tiered susceptibility monitoring strategy was developed that includes testing field populations at diagnostic concentrations and doses in first‐tier vial LC bioassays and second‐tier gel bait matrix LD bioassays. The vial method facilitates rapid identification of field strains with reduced susceptibility. The feeding bioassay effectively simulates field exposure to Advion^® and therefore has utility for secondary confirmation of susceptibility shifts and identification of behavioral resistance (i.e. bait aversion). Copyright © 2010 Society of Chemical Industry     

Insecticide resistance in houseflies from the middle east and North Africa with notes on the use of various bioassay techniques

The susceptibility to pyrethroid, organochlorine, organophosphorus and carbamate insecticides, of 20 strains of houseflies (Musca domestica L.) collected in the Middle East and North Africa, was assessed by topical application. No resistance to pyrethroids was found but most flies were resistant to DDT, gamma-HCH, organophosphorus and carbamate insecticides. Numerical factors of resistance for a susceptible and two different resistant strains, obtained using different bioassay techniques, were compared. High mortality (≥95%) was achieved with ‘resisted’ insecticides in tests with space sprays, but only low, variable mortality resulted from deposit tests. If this occurs under practical field conditions, moderately resistant populations of flies could be controlled by using space sprays containing comparatively high concentrations of active ingredient, but increased levels of deposit would be ineffective.     

Correlation of a resistance-associated Rdl mutation in the German cockroach, Blattella germanica (L), with persistent dieldrin resistance in two Danish field populations

Danish Blattella germanica (L) populations carry the resistance-associated mutation A302S within the Resistance to dieldrin (Rdl) gene. The mutation has remained in field populations long after the discontinuation of dieldrin for cockroach control. The mutation has also persisted in our laboratory strains with high and intermediate frequencies for more than 8 years without selection. The toxicity of dieldrin was tested by topical application to male cockroaches in the susceptible strain DPIL-SUS and two field strains, Zo960302 and Su960304, which were 1270- and 15-fold resistant to dieldrin at LD50. We report the sequencing of exon 7 of the B. germanica Rdl gene and the finding of the putative resistance-associated A302S mutation. We have developed and implemented a PCR-based diagnostic method with the detection of a restriction endonuclease polymorphism, which allows for easy discrimination of susceptible, resistant and heterozygote genotypes. The frequency of the resistance-associate allele A302S was 0.97 and 0.38 in the Zo960302 and Su960304 populations, respectively. The cockroach Rdl A302S allele confers high dieldrin resistance in homozygotes and intermediate resistance in heterozygotes, and its presence is responsible for the persisting dieldrin resistance in Danish populations of B. germanica.     

Juvenile hormone analogs: Toxicity and cross-resistance in the housefly

The toxicity of several juvenile hormone analogs (JHAs) to susceptible and insecticide-resistant housefly (Musca domestica L.) strains was determined by an assay procedure in which larvae were exposed to residues of JHAs in glass vials. All JHAs tested were toxic and the most active compound, isopropyl 11-methoxy-3, 7, 11-trimethylododeca-2, 4-dienoate, was 100 times as toxic to the susceptible Orlando Regular strain as methyl parathion and 600 times as toxic as DDT.A 5- to 30-fold tolerance to the different JHAs was present in an insecticide resistant strain in which resistance is associated with a high level of NADPH-dependent microsomal oxidase activity controlled by a gene(s) on chromosome II. Cross-resistance was less marked in a strain with a chromosome V high oxidase gene and absent in strains with other resistance mechanisms.The data indicate that cross-resistance to JHAs in insects may occur in certain strains with high levels of oxidative detoxifying activity. Even so, the most active JHA was far more toxic to both susceptible and resistant strains than methyl parathion or DDT.     

Genetic and biochemical mechanisms limiting fipronil toxicity in the LPR strain of house fly,Musca domestica

Fipronil is a new insecticide which exerts its toxic action by interacting with the insect GABA-gated chloride channel. Previous studies have shown that cyclodiene-resistant insects have low to moderate levels of cross-resistance to fipronil, while other resistant strains are usually susceptible. In contrast, we recently found a strain (LPR) of house fly (Musca domestica L) with 15-fold cross-resistance to fipronil that was not associated with cyclodiene resistance. Fipronil cross-resistance in LPR was inherited as an intermediately dominant, autosomal, multigenic trait. [¹⁴C]Fipronil was observed to penetrate into LPR flies more slowly than into susceptible flies. S,S,S-tributylphosphorotrithioate and diethyl maleate pretreatment did not reduce the level of fipronil cross-resistance, while piperonyl butoxide resulted in a slight decrease. These results indicate that decreased penetration and monooxygenase-mediated detoxification may be mechanisms contributing to fipronil cross-resistance in the LPR strain. © 1999 Society of Chemical Industry     

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     

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。     

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.     

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.     

The A302S mutation in Rdl that confers resistance to cyclodienes and limited cross-resistance to fipronil is undetectable in field populations of house flies from the USA

Fipronil is a relatively new insecticide with great potential for insect control, however widespread use of cyclodiene insecticides has selected for an A302S mutation in the Rdl (GABA gated chloride channel) allele. This mutation gives resistance to cyclodienes and limited cross-resistance to fipronil. Given the concern over the possible reduction in efficacy and/or lifetime that fipronil might be used for pest control (given the extensive use of cyclodienes in the past), it is important to know the frequency of the A302S Rdl mutation in field populations. To ascertain the relative frequency of the A302S Rdl mutation in house fly populations we used three experimental approaches. First, we attempted to select for fipronil resistance by initially treating 33,100 field collected flies and selecting 14 additional generations. We were unable to produce a highly resistant strain. Second, we directly sequenced field collected flies. Third, we tested field collected house flies with a diagnostic dose of dieldrin and then genotyped the survivors. Out of the 4750 flies tested, there were no Rdl resistance alleles detected. We conclude that the resistant Rdl allele is rare in house flies in the US due to decades without cyclodiene use and a fitness disadvantage (in the absence of cyclodienes) of the 302S Rdl allele. The limited cross-resistance provided by the cyclodiene resistant Rdl allele, combined with the very low frequency of this allele in field populations, suggests that fipronil could be a promising insecticide for house fly control.     

Resistance and cross-resistance to imidacloprid and thiamethoxam in the Colorado potato beetle Leptinotarsa decemlineata

One of the major challenges in managing the Colorado potato beetle, Leptinotarsa decemlineata (Say) is its remarkable ability to develop resistance to virtually every insecticide that has ever been used against it. Resistance is particularly common throughout northeastern USA as far north as Maine. The first instances of resistance to imidacloprid have already been reported from several locations in New York, Delaware and southern Maine. Rotating insecticides with different modes of action may delay insecticide resistance, but successful implementation of this technique depends on a good understanding of resistance and cross-resistance patterns in populations of target pests. LC(50) values were measured for imidacloprid and thiamethoxam in Colorado potato beetle populations from a variety of locations in the USA and Canada using diet incorporation bioassays. The field performance of imidacloprid, thiamethoxam and clothianidin against imidacloprid-resistant beetles on a commercial potato farm in southern Maine was also evaluated. Correlation between LC(50) values for imidacloprid and thiamethoxam was highly significant, even when populations previously exposed to thiamethoxam were excluded from the analysis. There was no statistically detectable difference in the LC(50) values between populations exposed to both insecticides and to imidacloprid alone. Applications of neonicotinoid insecticides at planting delayed build-up of imidacloprid-resistant beetle populations on field plots by 1-2 weeks but failed to provide adequate crop protection. Consistently with bioassay results, there was also substantial cross-resistance among the three tested neonicotinoid insecticides. Results of the present study support the recommendation to avoid rotating imidacloprid with thiamethoxam as a part of a resistance management plan.     

An electrophysiological investigation of the susceptible (cooper) and resistant (kdr; super-kdr) strains of the adult housefly,Musca domestica L

The electrical activity of abdominal nerves of the housefly, Musca domestica L., was used as a bioassay to study nerve sensitivity to DDT and deltamethrin in susceptible (Cooper) and resistant (kdr, super-kdr) strains. By this technique the resistant strains were less sensitive (approximately 10 000-fold) than Cooper, but the bioassay could not distinguish between super-kdr and kdr in their responses to either compound and so could not account for the greater resistance shown by flies with super-kdr above kdr flies when these insecticides are applied topically. Although factors other than nerve insensitivity may be involved, the compounds were applied to the preparation in aqueous saline solutions at, or close to, their solubility limits and this could have masked differences in responses of nerves from the resistant strains.     

抗吡虫啉桃蚜种群的选育及其交互抗性研究

采用浸渍法,在室内用吡虫啉对桃蚜敏感种群进行抗性选育,经过15代的连续汰选,获得抗性指数为14.34倍的抗吡虫啉桃蚜种群。对9种常用杀虫剂的交互抗性测定结果表明,该种群对拟除虫菊酯类如高效氯氟氰菊酯(抗性指数12.76倍)和溴氰菊酯(10.24倍),有机磷类如氧乐果(7.95倍)、辛硫磷(5.44倍)和甲胺磷(5.32倍)以及吡虫啉·高效氯氰菊酯混剂(8.90倍)均产生了不同程度的交互抗性,而对氨基甲酸酯类如灭多威(3.15倍)、有机氯类如硫丹(1.64倍)以及阿维菌素·辛硫磷混剂(2.31倍)等无明显的交互抗性。     

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     

小菜蛾对阿维菌素的抗性选育及交互抗性研究

用阿维菌素对小菜蛾进行室内抗性汰选,选择压为约杀死种群70％的剂量。连续施药7～8次即表现抗性趋势,汰选至11代,获得抗性指数为80.71的抗性种群(ABM-R)。ABM-R种群对所测试的有机磷杀虫剂乙酰甲胺磷、有机氯类的硫丹、沙蚕毒素类的杀螟丹、氨基甲酸酯类的灭多威、微生物杀虫剂Bt、磺胺脲类衍生物丁醚脲、芳基取代的吡咯杂环化合物虫螨腈和昆虫生长调节剂定虫隆、虫酰肼无交互抗性(R/S为0.73～1.19),而对苯基吡唑类氟虫腈的敏感性却有所上升(R/S为0.22)。增效剂试验显示,PB和唧对ABM-S种群无增效作用,而对ABM-R种群增效作用显著,增效比分别为24.57和13.61,表明多功能氧化酶和羧酸酯酶在抗性机制中可能起重要作用。