Title: Mechanisms of resistance to diflubenzuron in the house fly, Musca domestica (L.)
Abstract: Abstract 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 3 H- and 14 C-labeled diflubenzuron at N 1 C 2 and N 1 C 1 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.
Publication Year: 1979
Publication Date: 1979-02-05
Language: en
Type: article
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