title: Malathion-specific resistance in Anopheles stephensi from Pakistan.
abstract: A strain of Anopheles stephensi from Pakistan (MalR) was 8.7-fold resistant to malathion and 6.7-fold cross-resistant to phenthoate, but not to other carboxylesters; no cross-resistance to bendiocarb, fenitrothion, permethrin and carbaryl was detected. Resistance was not associated with elevated levels of general esterase activity, as determined by hydrolysis of naphth-l-yl acetate (alpha-NA), but was correlated with higher levels of malathion carboxylesterase (MCE) activity in vitro. The results suggest that a highly specific type of esterase mediated resistance, such as MCE, can best be detected by an enzyme specific assay rather than one for general esterase activity. A new, rapid and sensitive assay for mosquito MCE is given.
mesh_terms: D000818:Animals; D000852:Anopheles / Q000201:enzymology; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism; D006868:Hydrolysis; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology; D007814:Larva; D008294:Malathion / Q000494:pharmacology*; D009946:Organothiophosphorus Compounds / Q000494:pharmacology; D010154:Pakistan
chemical_list: D007306:Insecticides; D009946:Organothiophosphorus Compounds; D002265:Carboxylic Ester Hydrolases; C021528:malathion esterases; C008838:phenthoate; D008294:Malathion