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1.
The insecticidal activity of lindane analogs, in which some chlorine atoms were replaced by other groups susceptible to microsomal oxidative metabolism, was determined against mosquitos, house flies, and German cockroaches. When tested with a synergist, piperonyl butoxide, one of the methylthio analogs was as active as lindane, whereas several others were also highly active. By examining the ratio of synergized and unsynergized LD50 values (synergistic ratio value), the highly insecticidal methylthio, methoxy, and methyl analogs appear to undergo metabolic detoxication effectively in house flies. By means of in vitro metabolism experiments using microsomal fraction from house fly abdomen, the methoxy, ethoxy, and methylthio analogs were shown to be metabolized rapidly at similar rates. The synergized insecticidal activities of these compounds against various insect species relate linearly with each other, suggesting that the oxidative degradation is inhibited by the synergist to a similar extent and that the transport process to the site of action is not a limiting factor in determining the relative insecticidal activity.  相似文献   

2.
Metabolism experiments with rats showed that significant isotope effects (kHkD = 2.4 to 3.5) were associated with the in vivo formation of dichloro and trichlorophenylmercapturic acids from a 1:1 mixture of normal and hexadeuterated lindane. This is evidence that rate-determining dehydrogenation and dehydrochlorination, both of which proceed with significant isotope effects, are essential in the pathway of dichloro- and trichlorophenylmercapturic acid formation from lindane. No significant primary isotope effects were associated (kHkD = 1.31 ± 0.17) with the formation of monochlorophenylmercapturic acid. This suggests that the 1,2-dechlorination to tetrachlorocyclohexene followed by glutathione conjugation is the probable pathway that produces this metabolite from lindane.  相似文献   

3.
Hexadeuterio-lindane(γ-BHC-d6) was several times as toxic as lindane against the mosquito (Culex pipiens pallens), house fly (Musca domestica), German cockroach (Blattella germanica) and American cockroach (Periplaneta americana). The neuroexcitatory activity of these two compounds did not differ. Lindane was considerably synergized by piperonyl butoxide, but lindane-d6 was not. A large isotope effect was observed in the in vivo breakdown of lindane-d6. Thus, the intrinsic toxicities of both compounds are equivalent. The difference in insecticidal activity seems to be due to the different rates of detoxifying biodegradation caused by the kinetic deuterium isotope effect.  相似文献   

4.
Electrophysiological responses of labellar hairs of resistant and susceptible strains of the house fly were recorded at times following treatment of the hairs with DDT. Under the influence of DDT, the receptors of a hair discharged groups of impulses in high-frequency trains instead of the usual regular volley. The effect was observed to gradually spread to nontreated hairs. Among four strains chosen for gradation from high resistance to high susceptibility, in general the relative effectiveness of DDT corresponded to overall resistance as indicated by LD50 data. The highly resistant strain showed essentially no effects, and the other strains showed effects with some degree of recovery. Results for the highly susceptible strain were anomalous in not differing significantly from those of the moderately resistant strai. Unexpectedly small effects in the highly susceptible strain point to a strain characteristic not necessarily correlated with LD50 data.  相似文献   

5.
Electrophysiological responses of labellar hairs of resistant and susceptible strains of the house fly were recorded at times following treatment of the hairs with DDT. Under the influence of DDT, the receptors of a hair discharged groups of impulses in high-frequency trains instead of the usual regular volley. The effect was observed to gradually spread to nontreated hairs. Among four strains chosen for gradation from high resistance to high susceptibility, in general the relative effectiveness of DDT corresponded to overall resistance as indicated by LD50 data. The highly resistant strain showed essentially no effects, and the other strains showed effects with some degree of recovery. Results for the highly susceptible strain were anomalous in not differing significantly from those of the moderately resistant strai. Unexpectedly small effects in the highly susceptible strain point to a strain characteristic not necessarily correlated with LD50 data.  相似文献   

6.
Studies on the inheritance of resistance to lindane in a laboratory-selected strain of Tribolium castaneum, by making crosses between the resistant and a susceptible strain, showed that resistance in this strain is controlled by an autosomally inherited single gene which is incompletely dominant.  相似文献   

7.
There was no difference in dose response to abamectin between a laboratory strain of Colorado potato beetle (Leptinotarsa decemlineata (Say))from North Carolina and a multiple resistant strain from Massachusetts (LD50= 1.95 and 1.98 ng larva?1, respectively). Two abamectin-resistant strains were generated by separate means. The mutagen, ethyl methanesulfonate, was used to generate an abamectin-resistant strain (LD50= 29.4 ng larva?1) from the susceptible laboratory strain. The other resistant strain (LD50 = 45.3 ng larva?1) was generated through an intense selection with abamectin of a field strain contained in cages set up in existing potato fields. Resistance ratios calculated from LD50values for the two abamectin-resistant strains were 15-fold and 23-fold, respectively. Resistance ratios calculated from LD97values (21-fold and 38-fold, respectively) were higher than those calculated at LD50. Also, there were larvae in both resistant strains which were capable of surviving doses up to 100 ng larva?1, while the susceptible strain had no survivors at 10 ng larva?1. Although the logit mortality regression analysis produced statistically different lines for the two abamectin-resistant strains, the slopes of each appear to be the same. Both resistance factors were determined to be autosomal and incompletely recessive (0.26 to 0.4, respectively) via reciprocal F1crosses to the susceptible laboratory strain.  相似文献   

8.
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 × LD50) and 1570 pmol for the R-strain (0.1 × LD50). 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.  相似文献   

9.
Biodegradability of lindane analogs using house fly whole body, microsomes, and microsome supernatant fraction was examined. It decreased in the order of alkoxy ～ methylthio > methyl analogs > lindane in the whole body experiments, as well as with microsomes in the presence of NADPH. With the supernatant in the presence of glutathione, a different trend was observed. The synergistic effects of piperonyl butoxide when used together with lindane analogs were mostly explained in terms of the inhibition of the microsomal metabolism. Piperonyl butoxide was also shown to inhibit the penetration of compounds into the fly body and to make the central nervous system of the American cockroach less sensitive to the action of insecticides causing after and repetitive discharges. It was observed that the value of the percentage of metabolic disappearance of insecticides after a certain period decreases as the dose level initially applied in the whole body experiments increases. The synergistic ratio parallels the percentage of disappearance value after the insecticidal activity test period when a dose corresponding to the unsynergized LD50 is initially applied. When quantitative comparisons are required for biodegradability of insecticides using house flies as the test insects, it should be on the basis of direct metabolism experiments using a fixed dose throughout the series of insecticides, but not on the basis of the synergistic ratio.  相似文献   

10.
Resistance to 4,4′-dichlorodiphenyltrichloroethane (DDT) in the 91-R strain of Drosophila melanogaster is extremely high compared to the susceptible Canton-S strain (>1500 times). In addition to enhanced oxidative detoxification, the 91-R strain also has a reduced rate of DDT penetration, increased levels of reductive and conjugative metabolism, and substantially more excretion than the Canton-S strain. Contact penetration of DDT was ∼30% less with 91-R flies, which also had significantly more cuticular hydrocarbons and a thicker, more laminated cuticle compared to Canton-S flies, possibly resulting in penetration differences. DDT was metabolized ∼1.6-fold more extensively by 91-R than Canton-S flies, resulting in dichlorodiphenyldichloroethane (DDD), two unidentified metabolites and polar conjugates being formed in significantly greater amounts. 91-R flies also excreted ∼4-fold more DDT and metabolites than Canton-S flies. Verapamil pretreatment reduced the LD50 value for 91-R flies topically dosed with DDT by a factor of 10-fold, indicating that the increased excretion may involve, in part, ATP-binding cassette (ABC) transporters. In summary, DDT resistance in 91-R is polyfactorial and includes reduced penetration, increased detoxification and direct excretion.  相似文献   

11.
The mechanisms of resistance to the chitin synthesis inhibitor diflubenzuron were investigated in a diflubenzuron-selected strain of the house fly (Musca domestica L.) with > 1000 × resistance, and in an OMS-12-selected strain [O-ethyl O-(2,4-dichlorophenyl)phosphoramidothioate] with 380 × resistance to diflubenzuron. In agreement with the accepted mode of action of diflubenzuron, chitin synthesis was reduced less in larvae of the resistant (R) than of a susceptible (S) strain. Cuticular penetration of diflubenzuron into larvae of the R strains was about half that of the S. Both piperonyl butoxide and sesamex synergized diflubenzuron markedly in the R strains, indicating that mixed-function oxidase enzymes play a major role in resistance. Limited synergism by DEF (S,S,S-tributyl phosphorotrithioate) and diethylmaleate indicated that esterases and glutathione-dependent transferases play a relatively small role in resistance. Larvae of the S and R strains exhibited a similar pattern of in vivo cleavage of 3H- and 14C-labeled diflubenzuron at N1C2 and N1C1 bonds. However, there were marked differences in the amounts of major metabolites produced: R larvae metabolized diflubenzuron at considerably higher rates, resulting in 18-fold lower accumulation of unmetabolized diflubenzuron by comparison with S larvae. Polar metabolites were excreted at a 2-fold higher rate by R larvae. The high levels of resistance to diflubenzuron in R-Diflubenzuron and R-OMS-12 larvae are due to the combined effect of reduced cuticular penetration, increased metabolism, and rapid excretion of the chemical.  相似文献   

12.
药剂对小菜蛾抗性及敏感品系乙酰胆碱酯酶抑制作用比较   总被引：5，自引：1，他引：4  
采用浸叶法测定了云南通海、元谋和澜沧的小菜蛾plutella xylostella田间种群对常用杀虫剂的抗药性。结果表明,云南上述地区小菜蛾田间种群对各类杀虫剂均产生了不同程度的抗性。对有机磷类药剂的抗药性为1.74~31.1倍;对菊酯类药剂的抗药性为7.41~764倍;对阿维菌素类药剂则产生了 5.60~4.06×104倍的抗性。通过离体和活体试验测定了药剂对小菜蛾头部乙酰胆碱酯酶(AChE)的抑制作用。敌敌畏和灭多威对通海抗性品系AChE离体和活体内的抑制中浓度(I50)分别是敏感品系的209、26.5倍和2.21、2.16倍;敌敌畏对通海小菜蛾种群的离体和活体内抑制中时间(IT50)小于敏感品系,分别是敏感品系的0.32和0.17倍;而灭多威对通海小菜蛾种群的离体和活体内抑制中时间(IT50)则大于敏感品系,分别是敏感品系的1.37和1.74倍。  相似文献   

13.
The permethrin resistant strain (TR-strain) of the beet armyworm, Spodoptera exigua (Hübner), has 92.5-fold resistance to permethrin (at LD50 level) compared to the permethrin susceptible strain (TS-strain). Bioassay involving permethrin mixed with piperonyl butoxide, an inhibitor of microsomal cytochrome P450s, significantly reduced the resistance ratio from 92.5- to 7.9-fold. However, S,S,S-tributylphosphorotrithioate and diethylmaleate which are inhibitors of esterases and glutathione S-transferase, respectively, did not affect the resistance level. These results indicate that the detoxification of permethrin in the TR-strain was primarily due to the cytochrome P450 monooxygenases. LD50 for permethrin was increased to 4.5-fold by the pre-treatment of phenobarbital in the TS-strain. The effect of induction by phenobarbital was almost completely overcome by the piperonyl butoxide treatment. However, it was observed that phenobarbital treatment did not cause any change in the toxicity of permethrin to TR strain. Since this result deviated from the expectation that the metabolism of phenobarbital in the TR-strain should be greater than that in the TS-strain, it was deemed necessary to compare the metabolism of phenobarbital between the TS- and TR-strains. Comparison was made based on the concentration of phenobarbital in the hemolymph and whole body. The results showed no significant difference in phenobarbital treatment between the two strains used in this study suggesting the possibility that the induction system in TS-strain is different from the TR-strain.  相似文献   

14.
Aliesterase, carboxylesterase, and phosphorotriester hydrolase activities in six house fly strains were studied in relation to malathion resistance. Selection of two susceptible strains with malathion for three generations resulted in an increase in both carboxylesterase activity and LD50 of malathion, indicating that the increased detoxication by the enzyme was the major mechanism selected for malathion resistance. With the highly resistant strains, however, the carboxylesterase activity alone was not sufficient to explain the resistance level, and the involvement of additional mechanisms, including phosphorotriester hydrolase activity, was suggested. The E1 strain, which had high phosphorotriester hydrolase activity but normal or low carboxylesterase activity, showed a moderate level, i.e., sevenfold resistance. Upon DEAE-cellulose chromatography, two or three esterase peaks were resolved from susceptible, moderately resistant, and highly resistant strains. The substrate specificity, the sensitivity to paraoxon inhibition, and the αβ ratio of malathion hydrolysis were studied for each esterase peak from the different strains. The results suggested the existence of multiple forms of esterases with overlapping substrate specificity in the house fly.  相似文献   

15.
In two complete replicates of a 2 × 2-fractorial-designed experiment involving chlorobenzene and γ-hexachlorocyclohexane (lindane), the hepatotoxicity induced by a challenge dose of chlorobenzene was altered by the pretreatments due to selective changes in various metabolis pathways. Pretreatment with either toxicant, alone or in combination, elevated the relative metabolism of 1.12 g chlorobenzene/kg to conjugated and polar metabolites. The relative importance of these pathways was increased most by pretreatment with chlorobenzene + lindane and least with chlorobenzene. The incidence and severity of chlorobenzene-induced hepatocellular necrosis was dependent on how much the pretreatments increased excretion of these metabolites relative to that of p-chlorophenol, since the conjugates and polar metabolites represent an inactivation of the toxic chlorobenzene-3,4-epoxide whereas p-chlorophenol reflects its formation. Thus these changes in the metabolic pathways resulted in either (i) a marginally significant decrease in hepatotoxicity (chlorobenzene pretreatment); (ii) significant reduction in both the incidence and severity of the lesions (lindane pretreatment); or (iii) absence of centrilobular hepatocellular necrosis in all but 1 of 12 rats where a minimal degree of necrosis was present (chlorobenzene + lindane pretreatment). In this study, the effect of pretreatment with xenobiotics on chlorobenzene-induced hepatotoxicity was dependent on how much the pretreatments altered the inactivation of chlorobenzene-3,4-epoxide relative to its formation.  相似文献   

16.
Glutathione-dependent degradation of parathion was studied in six strains of houseflies to find out whether it might be important as a cause of resistance. When supernatant fractions of high-speed centrifuged homogenates were fortified with glutathione and incubated with parathion, water-soluble products were formed. The rate of parathion detoxication was highest in a malathion-resistant strain (c. 4 μg parathion degraded per abdomen per hour), lowest in a susceptible strain, and intermediate in some other organophosphate-resistant strains. In one of the latter strains, E1, the gene for glutathione-dependent degradation is located on the second chromosome, closely linked with gene cm+. This is the same chromosome on which gene a for low ali-esterase activity and hydrolytic detoxication of paraoxon is located. It is not likely that the gene for glutathione-dependent degradation is identical with gene a, since it is also present in strain Nie which lacks gene a, and, therefore, the presence of a separate gene which is called gene g is postulated.  相似文献   

17.
The toxicity of a promising new insecticide, imidacloprid, was evaluated against several susceptible and resistant strains of German cockroach and house fly. Imidacloprid rapidly immobilized German cockroaches followed by a period of about 72 h during which some cockroaches recovered. After 72 h there was no further recovery. Imidacloprid-treated houseflies were immobilized more slowly than treated cockroaches, with the maximum effect observed after 72 h, and there was no recovery. Based upon 72-h LD50 values imidacloprid was moderately toxic to German cockroaches (LD50 values were 6–8 ng mg-1) and had only low toxicity to house flies (LD50 140 ng mg-1). Piperonyl butoxide (PBO) blocked the observed recovery in German cockroaches. PBO also greatly enhanced the 72-h LD50 of imidacloprid from 43- to 59-fold in cockroaches and 86-fold in house flies. Two strains of German cockroach (Baygon-R and Pyr-R) showed >4-fold cross-resistance to imidacloprid. This cross-resistance could not be suppressed by PBO, suggesting that P450 monooxygenase-mediated detoxication is not responsible for this cross-resistance. Variation in the level of synergism observed with PBO (between strains) suggests the ‘basal’ level of monooxygenase-mediated detoxication of imidacloprid is quite variable between strains of German cockroach. The AVER and LPR strains of house fly showed significant cross-resistance to imidacloprid. PBO reduced the level of cross-resistance in AVER from >4·2-fold to 0·5-fold (i.e. the AVER strain LD50 was half that of the susceptible strain when both were treated with PBO), but PBO did not suppress the cross-resistance in LPR. These data suggest monooxygenases are the mechanism responsible for cross-resistance to imidacloprid in AVER, but not in the LPR strain. © of SCI.  相似文献   

18.
Comparisons with standard susceptible insects showed that a strain of Tribolium castaneum, with a specific resistance to malathion and its carboxylic ester analogues, had no cross-resistance to topical applications of natural pyrethrins. Another strain of T. castaneum, showing resistance to many organophosphorus (OP) insecticides, was cross-resistant to pyrethrins ( × 34) and eight synthetic pyrethroids also applied topically; least cross-resistance occurred with resmethrin ( × 2.2), bioresmethrin ( × 3.3) and phenothrin ( × 4.0). Generally larger resistance factors were recorded with formulations synergised by piperonyl butoxide (PB). The greatest cross-resistance encountered was with unsynergised tetramethrin ( × 338). Apart from tetramethrin, factors of synergism did not exceed 5.7 with either the susceptible or multi-OP resistant strains. PB antagonised six of the nine pyrethroids against the multi-OP resistant strain. Antagonism also occurred with two of these six, permethrin (cis: trans ratio 1:3) and 5-prop-2-ynylfurfuryl ( 1RS)-cis,trans-chrysanthemate (‘Prothrin’), against the susceptible strain. Considering only formulations without the synergist, the most effective compounds against the susceptible strain, relative to pyrethrins, were bioresmethrin (2.7) and permethrin (2.4). Similarly with the multi-OP resistant strain the most effective compounds were bioresmethrin (28), resmethrin (14) and permethrin (6.6). Thus the LD50 (the dose required to kill 50% of the test species) for bioresmethrin against the resistant strain (0.14 μg) only slightly exceeded the LD50 for pyrethrins against the susceptible strain (0.12 μg).  相似文献   

19.

BACKGROUND

Tebufenozide is widely used to control populations of the smaller tea tortrix, Adoxophyes honmai. However, A. honmai has evolved resistance such that straightforward pesticide application is an untenable long-term approach for population control. Evaluating the fitness cost of resistance is key to devising a management strategy that slows the evolution of resistance.

RESULTS

We used three approaches to assess the life-history cost of tebufenozide resistance with two strains of A. honmai: a tebufenozide-resistant strain recently collected from the field in Japan and a susceptible strain that has been maintained in the laboratory for decades. First, we found that the resistant strain with standing genetic variation did not decline in resistance in the absence of insecticide over four generations. Second, we found that genetic lines that spanned a range of resistance profiles did not show a negative correlation between their LD50, the dosage at which 50 % of individuals died, and life-history traits that are correlates of fitness. Third, we found that the resistant strain did not manifest life-history costs under food limitation. Our crossing experiments indicate that the allele at an ecdysone receptor locus known to confer resistance explained much of the variance in resistance profiles across genetic lines.

CONCLUSION

Our results indicate that the point mutation in the ecdysone receptor, which is widespread in tea plantations in Japan, does not carry a fitness cost in the tested laboratory conditions. The absence of a cost of resistance and the mode of inheritance have implications for which strategies may be effective in future resistance management efforts. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.  相似文献   

20.
A resistant strain of Phytoseiulus persimilis selected by methidathion pressure for several years metabolizes the [14C]methidathion faster than does the corresponding susceptible strain. The metabolism is for the main part glutathione dependent and gives the methidathion conjugate on glutathione as a first metabolite: S[5-methoxy-2-oxo-1,3,4-thiadiazol-3(2H)-yl]-l-glutathione. In addition, glutathione transferase with chlorodinitrobenzene as a substrate has a threefold lower Km in R strain than in S strain. Furthermore, this reaction is competitively inhibited by methidathion with a Ki which is threefold lower in R than in S strain. These results indicated that in this strain of P. persimilis resistance is due to an elevated detoxication of methidathion by a glutathione transferase. Other parameters known to be able to induce resistance in arthropods have been compared in resistant and sensitive strains. Esterase and monooxygenase activity measured with chromogenic substrates are the same in the two strains as is the level of acetylcholinesterase and its inhibition by methidathion oxon. No difference between the two strains has been found in the penetration kinetics measured with [14C]methidathion. These results indicated that glutathione transferase is the only mechanism which has been selected in P. persimilis, although other mechanisms are known to be involved in resistance to other insecticides in phytoseiid mites.  相似文献   

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