Resistant Strains Of House Flies Research Articles

Separation of multiple forms of acidic glutathione S‐transferase isozymes in a susceptible and a resistant strain of house fly, Musca domestica (L.)

The acidic glutathione S-transferases from a CSMA (susceptible) strain and a Cornell-R (resistant) strain of houseflies were purified and separated utilizing affinity chromatography followed by chromatofocusing. Nine fractions were isolated from each house fly strain. Fraction 1 had the highest 1-chloro-2,4-dinitrobenzene vs. 1,2-dichloro-4-nitrobenzene ratio (CDNB/DCNB ratio) in both strains and the ratio of all the other fractions tended to decrease as the isoelectrical points decreased except for fractions 4 and 9. Most fractions from the CSMA strain had higher CDNB conjugation activities than the fractions from the Cornell-R strain, but all the fractions from the CSMA strain had lower DCNB conjugation activities than fractions from the Cornell-R strain. Steady-state kinetics of all the fractions were examined. The Km values obtained from both strains ranged from 0.36 to 1.12 mM, while the Vmax value ranged from 3.0 to 32.6 mumol/min/mg. In the 100,000 g supernatant, the CDNB specific activities in the CSMA strain was about 1/3 of the activity in the Cornell-R strain but it was about 1.5-fold following affinity chromatography. The specific activity for DCNB measured in the CSMA strain was only 1/5 of the activities of the Cornell-R strain in the 100,000 g supernatant, but was about the same after affinity chromatography. The difference was due to the selectivity of the affinity column used in the current study.

DIPTEREX RESISTANCE IN THE HOUSEFLY AND THE SYNERGIC MECHANISM OF SV1 IN RELATION TO PENETRATION THROUGH CUTICLE

Abstract SV1 was observed to have obvious synergism and could delay housefly (Musca domestica vicina) resistance development to Dipterex. The penetration rates of Dipterex through housefly cuticle were determined in a susceptible and two resistant strains. The results indicated that the penetration in the resistant housefly strains was obviously slower than in the susceptible one. The penetrating rate of SV1+ Dipterex (in mixture) was higher than that of Dipterex. The penetration reduction in resistant houseflies may be an important factor in bringing forth resistance. The increase of the penetrating rate of Dipterex and the decrease of its metabolic rate are regarded as the important mechanisms of SV1 synergism to Dipterex.

Distinct Substrate Specificity of Cytochrome P450 Dependent Monooxygenase System for Fenvalerate and Diazinon Metabolism in Pyrethroid and Organophosphate Resistant Housefly Strains

交差抵抗性パターンの異なるイエバエ系統を用いて, ミクロゾームのレベルでMFOの fenvalerate と diazinon に対する基質特異性を比較した. その結果,fenvalerate の分解は diazinon の添加によって著しく影響を受けることが明らかになった. しかし, diazinon の分解は fenvalerate によって影響されず, 両殺虫剤基質の分解に関与するP450は必ずしも共通ではないことを予想させた. また, イエバエ系統間でCO差スペクトルの吸収極大波長に明らかな違いが認められた. これらのことより, イエバエのミクロゾームには両殺虫剤に対する特異性が異なる複数のP450分子種が含まれていることが示唆され, 益子系においてはとくに fenvalerate を分解するP450の活性が高いことが推察された.

Purification and characterization of a cytochrome P-450 from insecticide susceptible and resistant strains of housefly, Musca domestica L., before and after phenobarbital exposure.

A cytochrome P-450 (P-450) was purified from abdominal microsomes of untreated and phenobarbital treated susceptible (S+) and insecticide-resistant (LPR) houseflies using HPLC purification procedures. The purified P-450s exhibited the same apparent molecular masses (54,400 dalton) and could not be distinguished from each other on the basis of HPLC chromatographic properties, reduced CO-difference absorbance maxima (447 +/- 0.5 nm), or partial NH2-terminal sequences (MLLLLLLIVVTTLYIFAKL). Since these P-450s were indistinguishable and were immunologically identical to cytochrome P-450lpr we conclude that these P-450s are in fact cytochrome P-450lpr. The level of P-450lpr was increased twofold after PB exposure in the S+ strain, while the level of P-450lpr did not change in the LPR strain. Immunoinhibition of ECOD activity with anti-P-450lpr antiserum suggests that PB treatment in S+ house flies induced P-450lpr, and other forms of cytochromes P-450 with high activity toward this substrate.

Toxicokinetic Analysis, of Dermally Applied Diazinon in Resistant and Susceptible Houseflies, Musca domestica L.

Toxicokinetic analysis was employed to investigate significance of various factors responsible for resistance in susceptible and resistant strains of housefly to diazinon. Topical application and application by exposure to a residual film of the compound in holding vial was conducted. A significant difference was observed between the strains in the penetration rate of diazinon, the amount of diazoxon present, and the degree of AChE inhibition. the data also indicated a reversible exchange of diazinon between external surface of the flies and the holding vial by volatilization/rub-off and resorption of the compound by the flies. Certain k values estimated by computer simulation using the experimental data and differential equations derived from the toxicokinetic models proposed for the external and internal dynamics of diazinon demonstrated an inter-strain difference. In particular, the ratio of diazoxon degradation over activation of diazinon was much greater in the resistant strain than in the susceptible strain, suggesting that low accumulation of diazoxon was the most important resistance factor. Insensitive AChE also played an important role in vivo.

Immunological detection of cytochrome P450 from insecticide resistant and susceptible house flies ( Musca domestica)

An antiserum was raised in a rabbit against a cytochrome P450, termed P450 lpr, purified from the pyrethroid resistant LPR strain of house fly. This polyclonal antiserum was specific for P450 lpr as judged by both rocket immunoelectrophoresis and immunoblotting. The antiserum was used to detect immunoreactive cytochrome P450s in insecticide susceptible and resistant house flies. Single immunoreactive bands of a slightly variable position were obtained when crude microsomes from six insecticide resistant house fly strains (LPR, Dairy, Kashiwagura, 3rd-Y, EPR, ASPR) were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by immunoblotting, while immunoreactive bands were barely detectable in insecticide susceptible ( aabys, S+) strains. The immunoreactive cytochrome P450s were isolated from each of eight house fly strains by high-performance liquid chromatography. The isolated immunoreactive cytochrome P450s from all strains were immunologically identical to P450 lpr by fused rocket immunoelectrophoresis, and only those from the Kashiwagura and ASPR strains differed in chromatographic and/or electrophoretic properties from P450 lpr. Amounts of immunoreactive P450 were determined in house fly microsomes. Immunoreactive P450 represented 68% (specific content: 0.48 nmol/mg protein) of the total (0.72 nmol/mg) cytochrome P450 in LPR microsomes and 6.6% (0.011 nmol/mg) of the total (0.15 nmol/mg) cytochrome P450 in S+. Thus, immunoreactive P450 was constituitively expressed at 44-fold higher levels in insecticide resistant LPR flies compared to the susceptible S+ strain.

Synthesis and insecticidal activity of optically active 2-methoxy-5phenyl-1,3,2-oxazaphospholidine 2-sulfide.

Four optically active isomers (optical purity >94.6% d.e.) of 2-methoxy-5-phenyI-l,3,2-oxazaphospholidine 2-sulfide (5-PMOS) were synthesized by a two-step phosphorylating method, and their insecticidal activities were determined against susceptible (SRS) and resistant (3-YF) strains of house flies by topical application. The relationship between the configuration and insecticidal activity was similar in the susceptible and resistant strains of house flies. The (R)c(R)P-isomer showed the highest insecticidal activity, followed by (R)c(S)p>(S)c(R)p>(S)c(S)p.

A comparison of permethrin and methomyl insecticides for the control of a multiresistant strain of houseflies (Musca domestica)

AbstractA methomyl sugar bait formulation and permethrin residual spray were compared for the control of a multi‐insecticide resistant strain of housefly in a UK pig farm. The methomyl was applied as a granular scatter bait at the manufacturer's recommended rate of 25 mg m−2 active ingredient (a.i.) to the treated floor area. Permethrin was applied at 32, 64 and 128 mg m−2 a.i. to structural surfaces. The highest deposit rate of permethrin used was four times that recommended by the manufacturer for the control of flying insects. The methomyl bait gave effective control but the permethrin spray failed at all deposit rates tested. The use of permethrin increased resistance to this compound at the KD50 level from x 13 to x 560 within 10 weeks and significantly increased the proportion of flies resistant to natural pyrethrins synergised with piperonyl butoxide (P<0.01).

Characterization of multiple forms of cytochrome P-450 from an insecticide resistant strain of house fly ( Musca domestica)

Components of the microsomal monooxygenase system derived from abdominal preparations of an insecticide resistant house fly ( Musca domestica, Rutgers strain) were characterized. Cytochrome P-450 isozymes with molecular weights of 49,000, 53,000, 54,000, and 58,000 were partially purified using a procedure involving chromatography on columns of phenyl Sepharose, DEAE-cellulose (DE-52), carboxymethyl-Sepharose, hydroxylapatite, and an affinity column prepared from rat liver cytochrome b 5. Activity toward a variety of pesticides, as well as other exogenous and endogenous monooxygenase substrates, was examined using intact microsomes or purified isozymes in reconstituted systems. Oxidation of benzo[ a]pyrene in microsomal preparations was high although neither O-dealkylation of 7-ethoxyresorufin nor N-dealkylation of p-chloromethylaniline could be detected. Other substrates metabolized by abdominal microsomes from Rutgers flies included testosterone, lauric acid (primarily at in-chain positions), phorate, p-nitroanisole, and aldrin. Activity of abdominal microsomes from the susceptible CSMA strain toward benzo[ a]pyrene and lauric acid was, surprisingly, higher than that from the resistant Rutgers strain. Synergism between NADPH and NADH was noted with microsomes from either strain. Reconstitution experiments were relatively unsuccessful but activity toward lauric acid was obtained using a system that included purified cytochrome P-450 fractions, purified house fly or rat liver NADPH-cytochrome P-450 reductase, an NADPH generating system, and a phospholipid. Unlike similar systems utilizing mammalian cytochrome P-450, phosphatidylethanolamine was more active than phosphatidylcholine.

Genetical and Biochemical Studies on Resistance to Pyrethroid and Organophosphorus Insecticides

The mechanism of diazinon resistance in the Hokota strain, which was the first organophosphorus (OP) insecticide resistant houseflies reported in Japan in 1961, was investigated using 32P-diazinon and -diazoxon in vitro and in vivo. It was demonstrated that this strain has three resistant mechanisms: slow penetration of diazinon through the cuticle, high microsomal mixed function oxidase activity and high activity of phosphatase which hydrolyzes diazoxon, or an active metabolite of diazinon. About five years after the use of insecticide for housefly control had been completely stopped in order to sericulture, houseflies were collected from the same farm where the diazinon resistant Hokota fly had been found. Single pair culture of captured flies and a diazinon susceptibility test of the offspring showed that a high frequency of diazinon resistant genes was still present. The Akita-f was a strain subjected to selection with fenitrothion for 17 generations. Subsequent evaluation showed the resistance ratio of this then established fenitrothion resistant strain to susceptible SRS strain was about 4000. Crossing between Akita-f and SRS strains showed the fenitrothion resistance almost completely dominant. Linkage group analyses for the dominant factor were carried out using two multi-chromosomal marker strains by the F1 male backcross method, and the dominant resistant factor(s) was found to be associated only with the 2nd chromosome. The Wakamatsu-m strain, highly resistant to malathion, was established from a colony collected in Kitakyushu after more than 10 generations of selection with this chemical. The dominant factor(s) for malathion resistance was also located only on the 2nd chromosome. This strain possesses as its mechanisms of resistance high malathion carboxylesterase activity, high glutathione S-transferase activity and insensitive acetylcholinesterase. The linkage group of the dominant factor controlling high malathion carboxylesterase was analyzed. Results of the crossing experiments clearly showed that only the 2nd chromosome was associated with the dominant factor controlling high malathion carboxylesterase. Forty-two insect metabolites of trans- and cis-permethrin were identified in in vivo studies with American cockroaches, houseflies and cabbage loopers. The permethrin isomers were metabolized by hydrolysis and hydroxylation at the geminal-dimethyl group and the phenoxybenzyl group. The alcoholic and phenolic metabolites are excreted as glucosides, and carboxylic acid is excreted as glucosides and amino conjugates. The microsomal system was used for the metabolism of permethrin isomers by housefly and cabbage looper preparations. Esteric cleavage is more extensive for trans-permethrin than for cis-permethrin, while the relative extent of oxidative metabolism of the two isomers depends on the enzyme source. The Danish pyrethroid resistant housefly strain, 228e2b, showed cross resistance to all pyrethroid insecticides tested. Genetic study revealed that the factor resistant to permethrin was almost completely recessive and was located on the 3rd chromosome. A strain termed PyR which showed extreme resistance to pyrethroid insecticides was obtained after mating the 228e2b strain and Japanese OP resistant Wakamatsu-m strain, and after selections of their offspring by permethrin for 16 generations. In addition to nerve insensitivity, the PyR strain possessed, as a mechanism of resistance, high enzyme activity of microsomal oxidase which contributed to the detoxication of pyrethroids. Major pyrethroid resistance genes in PyR houseflies were located on the 2nd and 3rd chromosomes.

Sorghum (Sorghum bicolor) Seed Safeners as Insecticide Synergists

Certain oximes, including cyometrinil [(Z)-α-(cyanomethoxy)iminobenzeneacetonitrile], CGA-92194 [N-(1,3-dioxolan-2-yl-methoxy)-iminobenzeneacetonitrile], 2-pyridinealdoxime-O-benzyl ether (PA-B), and 2-pyridinealdoxime-O-phenethyl ether (PA-PE), which are known to protect sorghum from chloroacetanilide herbicides, increased the toxicity of the insecticide propoxur (o-isopropoxyphenyl-methyl carbamate) to a resistant strain of housefly (Musca domesticaL.). Flurazole [5-thiazolecarboxylic acid, benzyl ester, 2-chloro-4-(trifluoromethyl)], a nonoxime protectant for grain sorghum, had less effect on the toxicity of propoxur than did the oximes. Metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide], which can be used as a herbicide in sorghum [Sorghum bicolor(L.) Moench.] only if the seed have been treated with a protectant, also increased the toxicity of propoxur to houseflies. Commercially available insecticide synergists increase insecticide activity by inhibiting NADPH-dependent microsomal mixed-function oxidase activity. Sorghum coleoptiles possessed the enzyme system necessary to oxidize aldrin (1,2,3,4,10,10-hexachloro-1,4,4a,5,8,8a-hexahydro-1,4-endo-exo-5,8-dimethanonaphthalene) to dieldrin (1,2,3,4,10,10-hexachloro-6, 7-epoxy-1,4,4a,5,6,7,8,8a-octahydro-1,4-endo-exo-5,8-dimethanonaphthalene), which is a standard test for oxidative metabolism in insects. Under the conditions of these tests, the aldrin epoxidase activity in sorghum coleoptiles was not affected by pretreatment with cyometrinil or flurazole.

Toxicodynamics of malaoxon in house flies

The fate of malaoxon was studied in a susceptible and a resistant strain of house fly following topical application. Sublethal doses were used: 160 pmol for the S-strain (0.17 × LD 50) and 1570 pmol for the R-strain (0.1 × LD 50). The penetration rates are dose dependent and semilog plots of the external amount vs time show that these rates are not proportional to this external amount. Internal concentrations of malaoxon rapidly increase following administration, reach maximum values between 30 min and 2 hr (depending on dose), and then slowly decrease. The rate of metabolic degradation is highest in the early stage of the intoxication process. A three-compartment pharmacokinetic model is postulated to explain the experimental data quantitatively. The first compartment represents external malaoxon, the other two represent internal parent compound. Statistical analysis shows that the penetration rate is better described with a sum of two exponentials rather than with a single exponential decay. In the model, degradation occurs in the first internal compartment and is assumed to be first order. Malaoxon is distributed between the two internal compartments slowly with first-order kinetics. Parameter estimation with curve-fitting procedures for the internal processes (degradation and exchange) shows that there is not one set of parameter values that can be used for both strains simultaneously. This prompted a study of possible interstrain differences in degradation capacities. It was found that in vitro the R-strain had a fourfold higher oxidative breakdown rate of malaoxon. Taking this difference into account it is possible to explain the two sets of data with one kinetic model, although other alternatives cannot be excluded.

Polysubstrate monooxygenases (cytochrome P-450) in larvae of susceptible and resistant strains of house flies

The polysubstrate monooxygenases (PSMO or cytochrome P-450) of house fly larvae were studied at the mature larval or “clear gut” stage. Fat body and gut tissues were most efficient in the conversion of aldrin to dieldrin. Microsomal fractions of larval homogenates had the highest PSMO activities, with lower PSMO activities also found associated with mitochondrial fractions. Microsomes from Rutgers (resistant) larvae had higher levels of NADPH:cytochrome c reductase (2×), cytochrome P-450 (2×), aldrin (4×), and heptachlor (9×) epoxidases than microsomes from CSMA (susceptible) larvae. Cytochrome P-450 of Rutgers larvae had an absorption maximum at 449 nm, 2 nm lower than the cytochrome P-450 of CSMA larvae. n-Octylamine spectra showed that the level of high-spin cytochrome P-450 was higher in Rutgers larvae. NADPH:cytochrome c reductase, cytochrome P-450, and aldrin epoxidase were induced by phenobarbital, and Rutgers larvae were shown to be more sensitive to this inducer than CSMA larvae. Induction of larval PSMO by phenobarbital did not affect the expression or the inducibility of PSMO in adults.

Studies on the effect of phenobarbital on γ-glutamyl transferase activity in various housefly strains

The effect of pretreatment with phenobarbital (PB) on γ-glutamyl transferase (GGT) activity in an insecticide-susceptible housefly strain (CSMA) and three insecticide-resistant housefly strains (Fc, Rutgers, and Hirokawa) was investigated. Pretreatment with PB had little if any effect on GGT activity in the susceptible and resistant housefly strains, indicating that not all the enzymes involved in mercapturic acid biosynthesis in the housefly are inducible.

Studies on Biologically Active Organophosphorus Compounds

Two types of metabolic activation of triaryl phosphate to cause delayed neurotoxicity were disclosed: 1) tri-o-tolyl phosphate (TOCP) was converted into a highly active saligenin cyclic phosphate, 2-(o-tolyoxy)-4H-1, 3, 2-benzodioxaphosphorin 2-oxide, by the microsomal hydroxylation of a methyl group followed by cyclization, which was accelerated by plasma albumin; 2) tri-p-ethylphenyl phosphate (TPEP) was activated by similar hydroxylation at α-carbon atom followed by dehydrogenation to form α-oxo metabolites. Studies on structure-activity relationships by modifying the structure of the neurotoxic metabolites showed that the selective toxicity is governed greatly by the size of non-leaving groups (selectophore) and that the combination of the selectophore and phosphorylating activity, which is due to the cyclic ester structure in TOCP series and to the electron-withdrawing leaving group in TPEP series, decides the final biological activity of phosphorus compounds. Thus, the metabolite homologs carrying small alkyl group (s) as the non-leaving group in both series did not cause ataxia in hens, but exerted insecticidal activity. Salithion (2-methoxy-4H-1, 3, 2-benzodioxaphosphorin 2-sulfide) was therefore developed into a commercial insecticide. The phosphorylating property of saligenin cyclic phosphate esters was also utilized for the syntheses of biologically interesting natural phosphate esters by developing the thiolate isomer of salithion, MTBO. This has the advantage of oxidatively activatable thiolate ester group, in addition to the highly reactive cyclic ester structure of saligenin which also acts as a removable protective group. Some potent synergists of malathion were also found in the series of cyclic phosphorus esters related to the TOCP-metabolite. They were the potent inhibitors of carboxyesterase. Another synergist found was a thioquinol phosphate, which was obtained by modifying the metabolite of triphenyl phosphate, a malathion synergist. Another thiolate-type synergist IBP inhibited the degradation of malathion by inhibiting carboxyesterase and also demethylation in vivo. Finding L-leucine to be a neuroactive substance in the blood of silkworm larvae, we combined it and related amino acids with an extremely reactive five-membered cyclic phosphate and obtained novel insecticidal 4-isobutyl-2-methoxy-1, 3, 2-oxazaphospholidine 2-sulfide and the 4-isopropyl homolog. These were particularly effective to organophosphate resistant strains of houseflies. The structuretoxicity relationship of bicyclic phosphate esters, 4-substituted 2, 6, 7-trioxa-1-phospha-bicyclo [2.2.2] octanes, was characterized by the importance of the steric and hydrophobic properties of the bridge-head substituent for the high toxicity, which appeared to be due to their anti-GABA activity.

In vitro metabolism of EPN and EPNO in susceptible and resistant strains of house flies

EPN is twice as toxic as EPNO to house flies from both the Diazinon-resistant strain and the susceptible strain. EPN and EPNO are also eight times more toxic to the susceptible than the resistant strain. This is due to the ability of the resistant strain to metabolize these compounds to a greater extent. Metabolism by the glutathione S-transferases present in the 100,000g supernatant is more extensive than that by the NADPH-dependent microsomal mixed-function oxidases. The glutathione S-transferases are the major route of metabolism for EPN and appear to be the principal mechanism conferring resistance. EPN was metabolized by the microsomal fraction via oxidative desulfuration to the oxygen analog, EPNO, and by oxidative dearylation to p-nitrophenol. EPNO was metabolized by the same system to p-nitrophenol and desethyl EPNO as well as to an unknown metabolite. The soluble fraction metabolized EPN to p-nitrophenol, S-( p-nitrophenyl)glutathione, O-ethyl phenylphosphonothioic acid, and S-( O-ethyl phenylphosphonothionyl)glutathione. The identification of the latter conjugate demonstrates a new type of metabolite of organophosphorus compounds. EPNO was metabolized by the soluble fraction to p-nitrophenol and S-( p-nitrophenyl)glutathione.

ATPase and dehydrogenase activities from house flies susceptible and resistant to organochlorine insecticides

Comparisons were made on ATPase, glucose-6-phosphate dehydrogenase (G-6-PDH) and 6-phosphogluconate dehydrogenase (6-P-GDH) activities in strains of the house fly, Musca domestica L., susceptible and resistant to organochlorine insecticides. Oligomycin sensitive (OS) Mg 2+-ATPase was more sensitive to inhibition by DDT and aldrin than Na +K +-ATPase. OS-Mg 2+-ATPase was present at similar levels in susceptible and resistant strains of house flies and was equally sensitive to inhibition by the pesticides. Levels of Na +K +-ATPase were 40% lower in the two resistant strains of house flies than in the susceptible strain. In contrast to OS-Mg 2+-ATPase in the resistant strains, the Na +K +-ATPase was about 10 times less sensitive to inhibition by DDT and aldrin than in a susceptible strain. However, in vivo, DDT was a strong inhibitor of OS-Mg 2+-ATPase and a very weak inhibitor of Na +K +-ATPase. Activities of G-6-PDH and 6-P-GDH were 1.2- to 4.6-fold higher in the resistant strain compared to the susceptible strains. Increased dehydrogenase activities were noted in susceptible flies after in vivo exposure to DDT (100 ppm). Variations in levels of activity and in sensitivity to inhibition of the enzymes tested indicate that toxicity and resistance to organochlorine insecticides may be related to different enzymes associated with ATP production and utilization.

Syntheses and insecticidal activity of 8-isopropyl-6-oxabicyclo[3.2.1]octan-7-one, a partial skeleton of picrotoxinin, and related compounds.

The title lactone trans-7 with a partial structural resembling picrotoxinin 1, which is an antagonist of GABA, and some related lactones were synthesized, and their insecticidal activities were assayed on susceptible and resistant housefly strains. Lactone trans-7 showed the highest activity among the tested compounds in both strains. The configuration of the isopropyl group at C8 position was important for the insecticidal activity.

Cuticular lipids of two resistant and a susceptible strain of houseflies

AbstractA study was made of the composition of the cuticular lipids of two resistant strains of houseflies (Rutgers and Fc), both of which show a reduced rate of absorption of insecticides as a partial mechanism of resistance and a susceptible strain (CSMA). Total lipids, monoglycerides, diglycerides and sterol esters (except in the Fc strain), sterols, fatty acids and phospholipid phosphorus were higher in resistant strains than in the susceptible strain. Phosphatidyl‐ethanolamine and phosphatidyl‐choline were major constituents of the phospholipid fractions and were appreciably higher in the resistant strains. Cuticular wax contents did not differ among strains. Incorporation of lipid precursors, [U‐14]acetate and [32P]orthophosphate, was greater in the cuticle of one or both resistant strains, depending on the lipid component examined.

Effect of anomalous cuticular phospholipids on penetration of insecticides in susceptible and resistant house flies

The cuticular lipid composition of resistant and susceptible strains of house flies ( Musca domestica L.) was altered by incorporation of dl-carnitine and 2-dimethylaminoethanol into the artificial diet under axenic conditions. β-Methyl-choline or 2-dimethylaminoethanol partially replaced the naturally occurring phospholipids (phosphatidyl choline and phosphatidyl ethanolamine) in the cuticular lipids of the adult of all strains. Effects of altered cuticular lipid composition on absorption of DDT, dieldrin, diazinon, parathion, and carbaryl in susceptible and resistant strains of house flies were studied. Upon incorporation of β-methyl-choline, the absorption pattern in the susceptible strain was decreased slightly, but this qualitative change caused increased absorption of DDT, dieldrin, diazinon, and parathion in one or more resistant strains. Incorporation of 2-dimethylaminoethanol changed the absorption pattern of insecticides in both susceptible and resistant strains of house flies to a slightly greater extent than did β-methyl-choline.