Mechanism of Malathion and Parathion Resistance in the Two-Spotted Spider Mite, Tetranychus urticae1

The Activity and Organophosphate Inhibition of Cholinesterases From Susceptible and Resistant Ticks (Acari)

“…The lower cholinesterase activity and the resistance of this cholinesterase to organophosphates, which has been observed in homogenates of organophosphorus resistant tick larvae, is very similar to the findings of SMISSAERT, (1964) and Voss & MATSUMURA, (1964) who discovered that the same variations of activity and sensitivity to organophosphates occurred in colonies of two-spotted spider mites which were resistant to parathion (Leverkusen, LRR strain). A further similarity between tick and spider mite resistant cholinesterase is the lowered susceptibility to carbamate inhibition, which agrees well with the observed cross-resistance to carbamates in both species (SHAW, in press, Voss & MAT-SUMURA, 1964).…”

“…There was no increased degradation of organophosphate by resistant tick homogenates, and, in this respect, there is no resemblance between resistant cattle ticks and the American Blauvelt (BR) strain of resistant spider mites (MATsUMURA & VOSS, 1964). The combination of these observations with the enzyme studies suggests that heterozygotes are almost as resistant as homozygotes, and contribute the major part of the susceptible cholinesterase found in resistant strain homogenates.…”

“…One strain of the two-spotted spider mite (Tetranychus urticae) has responded to organophosphate selection pressure by the survival of individuals with an increased level of Parathion hydrolysis, but no change in level of other esterases (Voss & MATSOMURA, 1964;MATSUMURA & VOSS, 1964). One strain of the two-spotted spider mite (Tetranychus urticae) has responded to organophosphate selection pressure by the survival of individuals with an increased level of Parathion hydrolysis, but no change in level of other esterases (Voss & MATSOMURA, 1964;MATSUMURA & VOSS, 1964).…”

Detoxification Enzyme Differences Between a Herbivorous and Predatory Mite

“…In contrast to the finding for A. falla- 24 SEPTEMBER 1982 cis, general esterase activity appears to be lower in organophosphate-resistant than in susceptible T. urticae (24). However,' a specific carboxylesterase, obscured in an a-naphthyl acetate assay, contributes to development of organophosphate resistance in T. urticae (25), and for this strain other detoxification enzymes (for example, glutathione transferase), retarded penetration, or target site insensitivity may also be involved.…”

Relative toxicity of phorate and its metabolites to Tetranychus urticae Koch (Tetranychidae; Acarina) and Empoasca fabae Harris (Cicadellidae; Homoptera)

“…Phorate was ineffective against parathionresistant or aramite-resistant mites (Smith, 1952(Smith, , 1960. lAile populations of the two-spotted spider mite develop varying degrees of organophosphorous resistance, very little is known about the biochemical mechanisms involved (Matsumura, 1964). Resistance to parathion and other organic compounds was observed as early as 1949 (Jefferson, 1956) and the possibility of the transmission of resistance between strains of the two-spotted spider mii:e was recognized (Taylor and Smith, 1956).…”