Field Strain Of House Flies Research Articles

Genetics and mechanism of resistance to chlorantraniliprole in Musca domestica L. (Diptera: Muscidae).

The house fly, Musca domestica L. is an important mechanical vector of different pathogens of medical and veterinary importance. It is an organism well-known for its ability to develop insecticide resistance. In the current study, we investigated the genetic basis and mechanism of chlorantraniliprole resistance in a field strain of house fly by selecting it artificially in the laboratory with a commercial formulation of chlorantraniliprole (CTPR-SEL). After seven generations of consecutive selection with chlorantraniliprole, CTPR-SEL strain developed a 644-fold resistance compared with the Susceptible strain and a 3-fold resistance compared with the field strain. Reciprocal crossing between the CTPR-SEL and Susceptible homozygous strains revealed an autosomal and incomplete dominant mode of resistance to chlorantraniliprole. A direct test using a monogenic inheritance model based on chi-square analysis revealed that the resistance was governed by more than one gene. Bioassays with synergists indicated that esterases might be involved in the resistance of house fly to chlorantraniliprole. These findings may be helpful to the development of an improved strategy for chlorantraniliprole resistance management in house fly.

Status and preliminary mechanism of resistance to insecticides in a field strain of housefly (Musca domestica, L)

Resistance profiles of houseflies (Gol-RR) collected from a field in Golmud city, Qinghai province, China, were determined for seven insecticides using topical bioassays. Resistance ratios of >1219.51, 153.17, >35.43, 6.12, 3.24, 1.73, and 0.86-fold were obtained for propoxur, cypermethrin, imidacloprid, indoxacarb, chlorpyrifos, fipronil, and chlorfenapyr, respectively, relative to a laboratory susceptible strain (SS). Synergism experiments showed that piperonyl butoxide (PBO), triphenylphosphate (TPP), and diethyl maleate (DEM) increased propoxur toxicity by >105.71, >7.88, and >5.15-fold in the Gol-RR strain, compared with 5.25, 2.00, and 1.39-fold in the SS strain, indicating the involvement of P450 monooxygenases, esterases, and glutathione-S-transferase in conferring resistance. Although cypermethrin resistance was significantly suppressed with PBO, TPP, and DEM in the Gol-RR strain, the synergistic potential of these agents to cypermethrin was similar in the SS strain, demonstrating that metabolism-mediated detoxification was not important for conferring resistance to cypermethrin in the Gol-RR strain. However, the three agents did not act synergistically with imidacloprid, indicating that other mechanisms may be responsible for the development of resistance to this insecticide. Acetylcholinesterase (AChE) activity was 13.70-fold higher in the Gol-RR than in the SS strain, suggesting the properties of the AChE enzyme were altered in the Gol-RR strain. Thus, rotation of chlorfenapyr insecticide with other agents acting through a different mode with minimal/no resistance could be an effective resistance management strategy for housefly.

Cyromazine resistance in a field strain of house flies, Musca domestica L.: Resistance risk assessment and bio-chemical mechanism

Developing resistance management strategies for eco-friendly insecticides is essential for the management of insect pests without harming the environment. Cyromazine is a biorational insecticide with very low mammalian toxicity. Resistance to cyromazine has recently been reported in house flies from Punjab, Pakistan. In order to propose a resistance management strategy for cyromazine, experiments were planned to study risk for resistance development, possibility of cross-resistance and bio-chemical mechanisms. A field strain of house flies with 8.78 fold resistance ratio (RR) to cyromazine was re-selected under laboratory conditions. After seven rounds of selection (G1-G7), the RR values rapidly increased from 8.8 to 211 fold. However, these values declined to 81fold when the cyromazine selected (CYR-SEL) strain was reared without selection pressure, suggesting an unstable nature of resistance. The CYR-SEL strain showed lack of cross-resistance to pyriproxyfen, diflubenzuron, and methoxyfenozide. Synergism bioassays using enzyme inhibitors: piperonyl butoxide (PBO) and S,S,S-tributylphosphorotrithioate (DEF), and metabolic enzyme analyses revealed increased activity of carboxylesterase (CarE) and mixed-function oxidase (MFO) in the CYR-SEL strain compared to the laboratory susceptible (Lab-susceptible) strain, suggesting the metabolic resistance mechanism responsible for cyromazine resistance in the CYR-SEL strain. In conclusion, risk of rapid development of cyromazine resistance under consistent selection pressure discourages the sole reliance on cyromazine for controlling house flies in the field. The unstable nature of cyromazine resistance provides window for restoring cyromazine susceptibility by uplifting selection pressure in the field. Moreover, lack of cross-resistance between cyromazine and pyriproxyfen, diflubenzuron, or methoxyfenozide in the CYR-SEL strain suggest that cyromazine could be rotated with these insecticides whenever resistance crisis occur in the field.

Risk assessment, cross-resistance potential, and biochemical mechanism of resistance to emamectin benzoate in a field strain of house fly (Musca domestica Linnaeus)

Reduced sensitivity to insecticides in insect pests often results in control failures and increases in the dose and frequency of applications, ultimately polluting the environment. Reduced sensitivity to emamectin benzoate, a broad-spectrum agrochemical belonging to the avermectin group of pesticides, was reported in house flies (Musca domestica L.) collected from Punjab, Pakistan, in 2013. The aim of the present study was to investigate the risk for resistance development, biochemical mechanism, and cross-resistance potential to other insecticides in an emamectin benzoate selected (EB-SEL) strain of house flies. A field-collected strain showing reduced sensitivity to emamectin was re-selected in the laboratory for five consecutive generations and compared with a laboratory susceptible (Lab-Susceptible) reference strain, using bioassays. The field strain showed rapid development of resistance to emamectin (resistance ratio (RR) increased from 35.15 to 149.26-fold) as a result of selection experiments; however, resistance declined when the selection pressure uplifted. The EB-SEL strain showed reduction in resistance to abamectin, indoxacarb, and thiamethoxam. The results of synergism experiments using piperonyl butoxide (PBO) and S,S,S-tributylphosphorotrithioate (DEF) enzyme inhibitors and biochemical analyses revealed that the metabolic resistance mechanism was not responsible in developing emamectin resistance in the EB-SEL strain. In conclusion, the risk for the rapid development of emamectin resistance under continuous selection pressure suggests using a multifaceted integrated pest management approach for house flies. Moreover, the instable nature of emamectin resistance in the EB-SEL strain and lack of cross-resistance to other insecticides provide windows for the rotational use of insecticides with different modes of action. This will ultimately reduce emamectin selection pressure and help improving management programs for house flies without polluting the environment.

Comparative Effectiveness of Insecticides for Use Against the House Fly (Diptera: Muscidae): Determination of Resistance Levels on a Malaysian Poultry Farm.

In this study, the toxicology of two commercial larvicides--cyromazine (Neporex 50SP) and ChCy (combination of chlorpyrifos and cypermethrin, Naga 505)--and five commercial adulticides--thiamethoxam (Agita 10WG), cyfluthrin (Responsar WP), lambda-cyhalothrin (Icon 2.8EC), fipronil (Regent 50SC), and imidacloprid (Toxilat 10WP)--was examined against the WHO/VCRU (World Health Organization/ Vector Control Research Unit) susceptible strain and the AYTW (Ayer Tawar) field strain of house fly, Musca domestica L. These pesticides were administered topically, in the diet, or as a dry residue treatment on plywood. Probit analysis using at least five concentrations and the concentration that was lethal to 50% (LC(50)) of the organisms was applied to compare the toxicology and resistance levels of the AYTW population to different insecticides. In the larvicide laboratory study, ChCy was more effective than cyromazine, with a significantly lower LC(50) value when administered topically or in the diet, although the AYTW population was susceptible to both larvicides with a resistance ratio (RR) <10. For the adulticide laboratory study, cyfluthrin and fipronil exhibited the lowest LC50 values of the adulticides, indicating that they are both effective at controlling adult flies, although lambda-cyhalothrin showed moderate resistance (RR = 11.60 by topical application; 12.41 by plywood treatment). Further investigation of ChCy, cyromazine, cyfluthrin, and fipronil under field conditions confirmed that ChCy and cyromazine strikingly reduced larval density, and surprisingly, ChCy also exhibited adulticidal activity, which significantly reduced adult fly numbers compared with the control group. Cyfluthrin and fipronil were also confirmed to be effective, with a significant reduction in adult fly numbers compared with the control group.

Selection and Preliminary Mechanism of Resistance to Profenofos in a Field Strain of Musca domestica (Diptera: Muscidae) from Pakistan.

House flies are major insect pests at dairy farms in Pakistan and are mainly controlled with insecticides of different classes, including organophosphates. To develop a better resistance management strategy, a field strain of house flies was selected in the laboratory to study the potential for the development of resistance, possible mechanisms of resistance and cross-resistance to other insecticides. The selection of the field strain with profenofos for five consecutive generations resulted in the LC50 values to increase from 50.49 to 176.03 µg/ml, and the resistance ratio increased from 29.70 to 103.55 as compared with a laboratory-susceptible strain; however, the resistance was decreased significantly when the selected strain was reared for the next five generations without exposure to any insecticide. The profenofos-selected strain (Profen-SEL) showed cross-resistance to chlorpyrifos and deltamethrin but no cross-resistance observed to spinosad. Synergism studies with piperonyl butoxide and S,S,S-tributylphosphorotrithioate indicated that the resistance to profenofos was probably associated with esterase and, possibly, microsomal oxidase activity. Resistance to profenofos in the selected strain suggests that the resistance, owing to instability, could be overcome by switching off profenofos use for few generations in the field or by rotation with different insecticides having different modes of action.

Genetics and mechanism of resistance to deltamethrin in the house fly, Musca domestica L., from Pakistan.

Deltamethrin (a pyrethroid insecticide) has widely been used against the house fly, Musca domestica, a pest found in livestock facilities worldwide. Although, cases of both metabolic and physiological resistance to deltamethrin have been reported in different parts of the world, no studies have been reported to characterize this resistance in house flies from Pakistan. In the present study, we investigated a field strain of house flies for potential to develop resistance to deltamethrin. Also, its stability, possible mechanisms and cross-resistance potential to other insecticides. Before the selection experiments, the field strain showed 8.41-, 3.65-, 8.39-, 2.68-, 19.17- and 5.96-fold resistance to deltamethrin, bifenthrin, lambda-cyhalothrin, chlorpyrifos, profenofos and spinosad, respectively, compared with the reference strain (Lab-susceptible). Continuous selection of the field strain (Delta-SEL) with deltamethrin for six generations (G1-G6) in the laboratory increased the resistance ratio to 176.34 after bioassay at G7. The Delta-SEL strain was reared for the next four generations without exposure to deltamethrin and bioassayed at G11 which revealed that the resistance was stable. The Delta-SEL strain at G7 showed cross-resistance to all other insecticides except spinosad, when compared to the bioassays before the selection experiment (G1). Crosses between Delta-SEL and Lab-susceptible strains revealed an autosomal and incomplete dominant mode of resistance to deltamethrin. A direct test using a monogenic inheritance model revealed that the resistance was governed by more than one factor. Moreover, synergism studies with the enzyme inhibitors PBO and DEF reduced the resistance to deltamethrin in the selected strain up to 2.51- and 2.19-fold, respectively, which revealed that the resistance was possibly due to microsomal oxidase and esterase activity. It is concluded that the resistance to deltamethrin was autosomal and incompletely dominant. The high cross-resistance of bifenthrin, lambda-cyhalothrin, chlorpyrifos and profenofos in the Delta-SEL strain suggests that other insecticides would be necessary to counter the resistance. These results are therefore suggestive for implications in the management of insecticide resistance in house flies.

Thiamethoxam Resistance in the House Fly, Musca domestica L.: Current Status, Resistance Selection, Cross-Resistance Potential and Possible Biochemical Mechanisms.

The house fly, Musca domestica L., is an important ectoparasite with the ability to develop resistance to insecticides used for their control. Thiamethoxam, a neonicotinoid, is a relatively new insecticide and effectively used against house flies with a few reports of resistance around the globe. To understand the status of resistance to thiamethoxam, eight adult house fly strains were evaluated under laboratory conditions. In addition, to assess the risks of resistance development, cross-resistance potential and possible biochemical mechanisms, a field strain of house flies was selected with thiamethoxam in the laboratory. The results revealed that the field strains showed varying level of resistance to thiamethoxam with resistance ratios (RR) at LC50 ranged from 7.66-20.13 folds. Continuous selection of the field strain (Thia-SEL) for five generations increased the RR from initial 7.66 fold to 33.59 fold. However, resistance declined significantly when the Thia-SEL strain reared for the next five generations without exposure to thiamethoxam. Compared to the laboratory susceptible reference strain (Lab-susceptible), the Thia-SEL strain showed cross-resistance to imidacloprid. Synergism tests revealed that S,S,S-tributylphosphorotrithioate (DEF) and piperonyl butoxide (PBO) produced synergism of thiamethoxam effects in the Thia-SEL strain (2.94 and 5.00 fold, respectively). In addition, biochemical analyses revealed that the activities of carboxylesterase (CarE) and mixed function oxidase (MFO) in the Thia-SEL strain were significantly higher than the Lab-susceptible strain. It seems that metabolic detoxification by CarE and MFO was a major mechanism for thiamethoxam resistance in the Thia-SEL strain of house flies. The results could be helpful in the future to develop an improved control strategy against house flies.

Insecticide-insensitive acetylcholinesterase from a laboratory selected and a field strain of housefly ( Musca domestica) (L.)

1. 1. Acetylcholinesterase from the heads of a strain of houseflies selected for resistance to the carbamate insecticide methomyl, and from a methomyl-resistant field strain was found to be less sensitive to inhibition by methoml than that from a susceptible strain. 2. 2. The enzyme from resistant insects was also more tolerant to malaoxon, dichlorvos and bomyl but not to azamethiphos. 3. 3. The decrease in sensitivity to inhibition appeared to be due to an increase in affinity for substrate.

Laboratory studies on the mechanisms of resistance to permethrin in a field‐selected strain of house flies

AbstractEnhanced oxidative metabolism appeared to be a major factor involved in resistance to permethrin in a field strain of house flies, selected with permethrin over 4 years. This was shown in the 7.8‐fold synergism by piperonyl butoxide which reduced the resistance ratio from 97 to 15. The rate of permethrin detoxication was significantly higher (P=0.05) in the resistant flies compared with a susceptible strain or resistant flies pretreated with piperonyl butoxide. The esterase inhibitor S,S,S‐tributyl phosphorotrithioate did not reduce the level of resistance to permethrin in the resistant strain, although some hydrolytic metabolism was apparent. Rates of penetration were similar in susceptible and resistant flies and in resistant flies pre‐treated with piperonyl butoxide. A minor unidentified resistance factor, possibly reduced sensitivity of the nervous system, may also have been present in the resistant strain.

Phosphate resistance in a field strain of house flies.

SummaryOffspring from a field strain of house flies taken from the L.S.U. poultry farm in the Baton Rouge, Louisiana area in October 1957 were found by topical application to be highly resistant to malathion and DDT with varying degrees of resistance to the other insecticides tested. Malathion had been used exclusively for 3 years. Progeny from field strains taken from the same area in October and December 1958 were more resistant to malathion, perhaps due to continued use of the organic phosphates. In the resistant group the larval period was longer and pupation and emergence extended over a longer time interval than the Orlando, Florida susceptible strain.

Cross Resistance in a Diazinon-Resistant Strain of Musca domestica (L.)1

Laboratory selection of a Diazinon® ( 0,0 -diethyl 0 -(2-iso- propyl-4-methyl-6-pyrimidinyl phosphorathioate )-resistant field strain of house fly, Musca domestica ( (L,), for nine generations on Diazinon-treated panels increased resistance not only to Diazinon but to a wide variety of insecticides. The levels of resistance to the various materials, as determined by topical application, were: Diazinon (38-fold), parathion (16), ronnel (18), Chlorthion® ( O -(3-chloro-4-nitrophenyl 0,0 -dimethyl phosphorothioate) (23), malathion (5), Sevin® (1-naphthyl- N -methyl carbamate) (more than 37-fold), Isolan®(dimethyl 5-(I-isopropyl-3-methyl-pyrazolyl) carbamate) (14), Pyrolan® (dimethyl 5-(3-methyl-I-phenylpyrazolyl) carbamate) (10), chlordane (400), dieldrin (220), lindane (250), DDT (more than 6,400-fold), TDE (more than 1,300), methoxychlor (more than 3,600), Dilan® (1 part 1,1-his( p -chlorophenyl)-2-nitropropane and 2 parts (I,I-bis( p -chlorophenyl)-2-nitrobutane) (10) allethrins (5), pyrethrins (4), and Lethane 384® (2-(2-butoxyethoxy) ethyl thiocyanate) (2-fold). These increases in tolerance, except to Lethane, pyrethrins, allethrins, and malathion (which may be simply instances of vigor tolerance), are considered true resistances. The extent of cross-resistance indicates that most of the contemporary materials will be ineffective against Diazinon- resistant flies. It is suggested that phosphorodithioates, more stable carbamates, or more toxic thiocyanates may offer promise for control. Tests on resistant flies collected from the field without further selection on Diazinon in the laboratory indicate that the pattern of resistance determined in this study is very similar to that which occurs under completely natural conditions of selection.