Nicotinoid and pyrethroid insecticide resistance in houseflies (Diptera: Muscidae) collected from Florida dairies

BACKGROUND: The housefly, Musca domestica L., continues to be a major pest of confined livestock operations. Houseflies have developed resistance to most chemical classes, and new chemistries for use in animal agriculture are increasingly slow to emerge. Five adult housefly strains from four Florida dairy farms were evaluated for resistance to four insecticides (beta‐cyfluthrin, permethrin, imidacloprid and nithiazine). RESULTS: Significant levels of tolerance were found in most field strains to all insecticides, and in some cases substantial resistance was apparent (as deduced from comparison with prior published results). At the LC₉₀ level, greater than 20‐fold resistance was found in two of the fly strains for permethrin and one fly strain for imidacloprid. Beta‐cyfluthrin LC₉₀ resistance ratios exceeded tenfold resistance in three fly strains. The relatively underutilized insecticide nithiazine had the lowest resistance ratios; however, fourfold LC₉₀ resistance was observed in one southern Florida fly strain. Farm insecticide use and its impact on resistance selection in Florida housefly populations are discussed. CONCLUSION: Housefly resistance to pyrethroids is widespread in Florida. Imidacloprid resistance is emerging, and tolerance was observed to both imidacloprid and nithiazine. If these insecticides are to retain efficacy, producer use must be restrained. Copyright © 2009 Society of Chemical Industry     

Biochemical study of resistance to imidacloprid in B biotype Bemisia tabaci from Guatemala

Systemic uptake bioassays using excised cotton leaves confirmed resistance to imidacloprid in a Guatemalan population of the tobacco whitefly Bemisia tabaci Gennadius. Polyacrylamide gel electrophoresis of naphthyl esterases identified the insects as B-types. Upon collection from the field, resistance was determined to be 58-fold relative to a susceptible strain originating in the Imperial Valley of California. Resistance levels increased to 126-fold in this population during its continuous exposure to systemically treated cotton. In biochemical investigations, there was no detectable NADPH-dependent mixed function oxidase metabolism of 14C-imidacloprid at any time during the selection process. In contrast, microsomal preparations from housefly abdomens readily produced significant amounts of the mono-hydroxy and olefin derivatives of the parent compound. Detoxification of imidacloprid by housefly MFOs may account for reports of lower toxicity of the insecticide towards this insect compared with whiteflies, despite similar binding properties between imidacloprid and the nicotinic acetylcholine receptors in both species.     

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.     

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     

Imidacloprid resistance and its mechanisms in field populations of brown planthopper, Nilaparvata lugens Stål in China

Imidacloprid is a key insecticide universally used for control of brown planthopper (BPH), and its resistance had been studied previously with laboratory selected strains. When the failure in field control happened in China in 2005, imidacloprid resistance in field populations of BPH (AQ, NJ, GL and WJ) was monitored and studied. The results demonstrated that the BPH of field populations had developed moderate to high level of resistance to imidacloprid. This resistance is attributed mainly to the enhanced P450 monooxygenases detoxification and could be enhanced in the same growing season if the insecticide was sprayed over and over. Further studies revealed that imidacloprid resistant hoppers did not show cross-resistance to all the neonicotinoid insecticides and high level of imidacloprid resistance in BPH was very unstable. Thus, efficient substitute neonicotinoids could be selected and “window control” could be implemented in resistance management. For checking the resistance mutation previously reported in laboratory selected strains, new corresponding target subunit genes were cloned and sequenced, but no mutations were found associated consistently with resistance.     

Beta-cypermethrin resistance associated with high carboxylesterase activities in a strain of house fly, Musca domestica (Diptera: Muscidae)

A housefly strain, originally collected in 1998 from a dump in Beijing, was selected with beta-cypermethrin to generate a resistant strain (CRR) in order to characterize the resistance and identify the possible mechanisms involved in the pyrethroid resistance. The resistance was increased from 2.56- to 4419.07-fold in the CRR strain after 25 consecutive generations of selection compared to a laboratory susceptible strain (CSS). The CRR strain also developed different levels of cross-resistance to various insecticides within and outside the pyrethroid group such as abamectin. Synergists, piperonyl butoxide (PBO) and S,S,S-tributyl phosphorotrithioate (DEF), increased beta-cypermethrin toxicity 21.88- and 364.29-fold in the CRR strain as compared to 15.33- and 2.35-fold in the CSS strain, respectively. Results of biochemical assays revealed that carboxylesterase activities and maximal velocities to five naphthyl-substituted substrates in the CRR strain were significantly higher than that in the CSS strain, however, there was no significant difference in glutathione S-transferase activity and the level of total cytochrome P450 between the CRR and CSS strains. Therefore, our studies suggested that carboxylesterase play an important role in beta-cypermethrin resistance in the CRR strain.     

棉蚜对吡虫啉抗性的初步研究

用吡虫啉对棉蚜进行室内抗性筛选,用药处理25次后抗性是筛选前的20.03倍;2007年对田间棉蚜进行抗性调查,发现不同地区种群对吡虫啉的抗性差异显著,江苏南京种群最为敏感,河南安阳、山东泰安和北京地区棉蚜与之相比,抗性分别为2.21、7.63和9.53倍;抗、感品系解毒酶活力分析发现,抗性品系的谷胱甘肽S-转移酶活性增加很少(比活力1.12倍),但酯酶活力显著高于敏感品系(比活力1.71倍);增效试验结果表明,顺丁烯二酸二乙酯(DEM)在抗、感品系中对吡虫啉均没有明显的增效作用,而磷酸三苯酯(TPP)和增效醚(PBO)虽然在敏感品系中对吡虫啉的增效作用较小(SR 1.24和1.29),但在抗性品系中的增效作用显著增高(SR 2.13和1.74);此外还发现,吡虫啉处理可提高棉蚜群体的酯酶活力。由此认为,棉蚜至少具有对吡虫啉产生中等水平抗性的风险,其抗性可能是由于棉蚜的酯酶和P450单加氧酶的解毒能力提高所致。     

Cross‐resistance,inheritance and biochemical mechanisms of imidacloprid resistance in B‐biotype Bemisia tabaci

BACKGROUND: The B‐type Bemisia tabaci (Gennadius) has become established in many regions in China, and neonicotinoids are extensively used to control this pest. Imidacloprid resistance in a laboratory‐selected strain of B‐type B. tabaci was characterised in order to provide the basis for recommending resistance management tactics. RESULTS: The NJ‐Imi strain of B‐type B. tabaci was selected from the NJ strain with imidacloprid for 30 generations. The NJ‐Imi strain exhibited 490‐fold resistance to imidacloprid, high levels of cross‐resistance to three other neonicotinoids, low levels of cross‐resistance to monosultap, cartap and spinosad, but no cross‐resistance to abamectin and cypermethrin. Imidacloprid resistance in the NJ‐Imi strain was autosomal and semi‐dominant. It is shown that enhanced detoxification mediated by cytochrome‐P450‐dependent monooxygenases contributes to imidacloprid resistance to some extent in the NJ‐Imi strain. Results from synergist bioassays and cross‐resistance patterns indicated that target‐site insensitivity may be involved in imidacloprid resistance in the NJ‐Imi strain of B. tabaci. CONCLUSION: Although oxidative detoxification mediated by P450 monooxygenases is involved in imidacloprid resistance in the NJ‐Imi strain of B‐type B. tabaci, target‐site modification as an additional resistance mechanism cannot be ruled out. Considering the high risk of cross‐resistance, neonicotinoids should be regarded as a single group when implementing an insecticide rotation scheme in B. tabaci control. Copyright © 2009 Society of Chemical Industry     

不同用药策略对抗性家蝇抗性演变的影响

据资料表明 ,目前大部分的农业、卫生害虫都已对一种或多种农药产生不同程度的抗性 ,而且几乎涉及所有类型农药 [1 ] 。如何通过科学用药来抑制或延缓抗性种群的抗性发展 ,成为我们今后抗性治理的重点和难点。针对敏感和抗性初始频率较低的种群所采用的轮用、混用以及使用增效剂等用药策略对有一定抗性水平的抗性种群是否仍然奏效 ?针对这一问题 ,作者以对溴氰菊酯已产生中等抗性 ( R/ S=2 8.2 4)和高等抗性 ( R/ S=5 4.1 2 )的家蝇为试虫 ,采用轮用 (换用辛硫磷 )、混用 (辛硫磷与溴氰菊酯的混剂 )、使用增效剂(溴氰菊酯与增效磷混剂 )三…     

Inheritance mode and realized heritability of resistance to imidacloprid in the brown planthopper,Nilaparvata lugens (Stål) (Homoptera: Delphacidae)

BACKGROUND: The brown planthopper, Nilaparvata lugens (Stål), is a serious pest that causes enormous losses to the rice crop in Asia. The genetic basis of imidacloprid resistance was investigated in N. lugens. RESULTS: The resistant strain, selected for imidacloprid resistance from a field population of N. lugens collected from Nanjing, Jiangsu Province, China, showed a 964‐fold resistance compared with the laboratory strain. Progenies of reciprocal crosses (F₁ and F₁′) showed similar dose–mortality responses (LC₅₀) to imidacloprid, and also exhibited a similar degree of dominance (D), 0.58 for F₁ and 0.63 for F₁′. Chi‐square analyses of self‐bred and backcross progenies (F₂, F₂′ and BC respectively) rejected the hypothesis for a single gene control of the resistance. The estimated realized heritability (h²) of imidacloprid resistance was 0.1141 in the resistant strain of N. lugens. CONCLUSION: The results showed that imidacloprid resistance in N. lugens was autosomal and was expressed as an incompletely dominant trait, probably controlled by multiple genes. Copyright © 2009 Society of Chemical Industry     

Two cytochrome P450 genes are involved in imidacloprid resistance in field populations of the whitefly, Bemisia tabaci, in China

The sweet potato whitefly, Bemisia tabaci (Gennadius) (Hemiptera:Aleyrodidae), is an invasive and damaging pest of field crops worldwide. The neonicotinoid insecticide imidacloprid has been widely used to control this pest. We assessed the species composition (B vs. Q), imidacloprid resistance, and association between imidacloprid resistance and the expression of five P450 genes for 14–17 B. tabaci populations in 12 provinces in China. Fifteen of 17 populations contained only B. tabaci Q, and two populations contained both B and Q. Seven of 17 populations exhibited moderate to high resistance to imidacloprid, and eight populations exhibited low resistance to imidacloprid, compared with the most susceptible field WHHB population. In a study of 14 of the populations, resistance level was correlated with the expression of the P450 genes CYP6CM1 and CYP4C64 but not with the expression of CYP6CX1, CYP6CX4, or CYP6DZ7. This study indicates that B. tabaci Q has a wider distribution in China than previously reported. Resistance to imidacloprid in field populations of B. tabaci is associated with the increased expression of two cytochrome P450 genes (CYP6CM1 and CYP4C64).     

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     

Resistance and cross-resistance to neonicotinoid insecticides and spinosad in the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae)

The Colorado potato beetle, Leptinotarsa decemlineata (Say), has developed resistance to many insecticides used for its control, recently including imidacloprid, a neonicotinoid compound. Other neonicotinoids are now being deployed to control this pest. A key point in the strategies of resistance management is the monitoring of resistance and cross-resistance. In the summer of 2003, imidacloprid-resistant adult Colorado potato beetles collected from Long Island, New York, USA were bioassayed using topical applications of imidacloprid and nine other neonicotinoids. Compared to a standard susceptible strain, the Long Island beetles showed 309-fold resistance to imidacloprid, and lower levels of cross-resistance to all other neonicotinoids, despite these never having been used in the field, i.e., 59-fold to dinotefuran, 33-fold to clothianidin, 29-fold to acetamiprid, 28-fold to N-methylimidacloprid, 25-fold to thiacloprid, 15-fold to thiamethoxam, 10-fold to nitenpyram, but less than 2-fold to nicotine. In injection bioassays, high resistance to imidacloprid was also found (116-fold). Piperonyl butoxide partially suppressed resistance to imidacloprid, but the resistance level was still over 100-fold, indicating that other mechanisms were primarily responsible for resistance. Low levels of resistance (8- to 10-fold) were found to the nicotinic activator, spinosad, in an imidacloprid-resistant strain collected from the same field in 2004. The cross-resistance seen with all the neonicotinoids tested suggests that the rotation of imidacloprid with other neonicotinoids may not be an effective long-term resistance management strategy. Rotation with spinosad also carries some risk, but it is unlikely that spinosad resistance in this case is mechanistically related to that for the neonicotinoids.     

Selection for imidacloprid resistance in Nilaparvata lugens: cross-resistance patterns and possible mechanisms

A field population of brown planthoppers (Nilaparvata lugens St?l) was collected and selected for imidacloprid resistance in the laboratory. The resistance increased by 11.35 times in 25 generations and the resistance ratio reached 72.83 compared with a laboratory susceptible strain. The selected resistant strain showed obvious cross-resistance to all the acetylcholine receptor targeting insecticides tested (monosultap 1.44-fold, acetamiprid 1.61-fold, imidacloprid homologues JS599 2.46-fold and JS598 3.17-fold), but not to others. Further study demonstrated that TPP and DEM had no synergism on imidacloprid. However, PBO displayed significant synergism in some different strains, and the synergism increased with resistance (S strain 1.20, field population 1.43 and R strain 2.93). PBO synergism to cross-resistant insecticides was also found in the resistant strain (monosultap 1.25, acetamiprid 1.39, JS598 1.94 and JS599 2.02). We concluded that esterase and glutathione S-transferase play little role in imidacloprid detoxification. The increase of the P450-monooxygenases detoxification is an important mechanism for imidacloprid resistance and target resistance may also exist in this species.     

不同地区灰飞虱对吡虫啉的抗性

为了明确全国不同稻区灰飞虱对吡虫啉的抗药性水平及其抗性机制,2012年采用点滴法测定了16个灰飞虱田间种群对吡虫啉的抗性倍数和3种增效剂在10个抗性种群中对吡虫啉的增效作用。结果表明,安徽安庆、合肥、江苏南京、盐城和无锡5个地区种群达到高抗水平(抗性倍数为74.1~91.2);浙江杭州、台州、湖州3个种群达到中等水平抗性(抗性倍数为35.8~47.7),福建福州和广东广州达到低水平抗性(抗性倍数为18.4~21.3),其他地区种群处于敏感性下降阶段。增效剂增效结果表明,氧化胡椒基丁醚(PBO)和磷酸三苯酯(TPP)在5个高抗种群和2个低抗种群中对吡虫啉均具有增效作用,表明P450单加氧酶和羧酸酯酶是抗性产生的主要代谢机制,而3个中抗种群中,仅PBO对吡虫啉表现出显著的增效作用,说明这3个种群仅有P450单加氧酶是其抗性上升的主要代谢机制。顺丁烯二酸二乙酯(DEM)在测定的10个种群中对吡虫啉均没有增效作用,说明谷胱甘肽S-转移酶没有参与其抗性上升。建议在中等水平至高水平抗性地区暂停使用吡虫啉防治灰飞虱。     

Novel mode of action of spinosad: Receptor binding studies demonstrating lack of interaction with known insecticidal target sites

The ability of spinosyn A to either enhance or displace binding to selected insecticidally-relevant receptors was investigated using a number of radioligands including, [³H]imidacloprid and [³H]ivermectin in tissues from the ventral nerve cord (VNC) membranes of the American cockroach, Periplaneta americana and head membranes from the housefly, Musca domestica. In these insect neural tissues, spinosyn A does not appear to alter the binding of a number of radioligands suggesting that spinosyn A does not interact directly with a variety of known receptors, including nicotinic or γ-aminobutyric acid (GABA)-based insecticidal target sites. However, available data are consistent with spinosyn A interacting with a site distinct from currently known insecticidal target sites, thus supporting a novel insecticidal mechanism of action for the spinosyns.     

Apparent Tolerance of a Field-Collected Strain of Myzus nicotianae to Imidacloprid due to Strong Antifeeding Responses

A French strain of the tobacco aphid Myzus nicotianae Blackman (Homoptera: Aphididae), strain FR, showed high tolerance to imidacloprid in short-term (48-h) oral ingestion bioassays when compared to a susceptible reference strain of Myzus persicae, strain NS. The resulting tolerance factors were >50. Measures of the contact activity of imidacloprid by the FAO dip method failed to detect these high factors of tolerance. The tolerance factor was in general <10 when using the dip method. The resulting difference between tolerance factors could be attributed to a behavioural component to fitness between strain FR and strain NS as further experiments revealed. When measuring the effect of systemically applied imidacloprid on honeydew excretion, a 50% reduction occurred in both strain FR and strain NS at nearly the same concentration of imidacloprid, providing evidence for a similar antifeedant response in both strains. Starvation experiments revealed that the French strain was able to survive approximately 24 h longer than a reference laboratory strain of M. persicae. This result coincided with the fact that systemically applied imidacloprid showed the same aphicidal potential against strain FR after three days as against strain NS after two days, i.e. 24 h later. After rearing in the laboratory for six months the French strain of M. nicotianae lost its hardiness and also its apparent ability to tolerate imidacloprid. However, strain FR was a heterogeneous field strain and it is possible that a susceptible variant out-reproduced a more hardy variant. These findings indicate that the type of bioassay is very important when assessing aphid populations for resistance against the chloronicotinyl insecticide imidacloprid, because of its distinct mode of action. It is obvious that an aphid dip test, i.e. FAO dip test, produces more reliable results than the different kinds of short-term oral ingestion bioassays, because of the reversible behavioural changes induced by imidacloprid after oral uptake. Thus a short-term oral ingestion bioassay (≤48 h) is not recommended for precise detection of possible resistance of Myzus sp. to imidacloprid, although this mode of uptake for imidacloprid might be sometimes more realistic in terms of field behaviour. The ideal test to generate most accurate data would be a slightly longer (72-h) feeding bioassay, perhaps used in conjunction with a dip test. The possible influence of the results on resistance monitoring is discussed. © 1997 SCI.     

Insecticide resistance in Bemisia tabaci (Homoptera: Aleyrodidae) populations from Crete

The resistance levels to alpha-cypermethrin, bifenthrin, pirimiphos-methyl, endosulfan and imidacloprid were determined in Bemisia tabaci (Gennadius) from Crete. Five B tabaci populations collected from greenhouse and outdoor crops were bioassayed and compared with a reference susceptible strain. Bemisia tabaci collected in a floriculture greenhouse exhibited the highest resistance against all insecticides: at LC50, resistance factors were 23-fold for bifenthrin, 80-fold for alpha-cypermethrin, 18-fold for pirimiphos-methyl, 58-fold for endosulfan and 730-fold for imidacloprid. A population collected on outdoor melons was more susceptible than the reference strain against all insecticides tested, suggesting the occurrence of local highly susceptible B tabaci populations in 'refugia'. In pairwise comparisons of resistance levels, correlation was observed between the LC50 values of the pyrethroid insecticides bifenthrin and alpha-cypermethrin.     

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。