摘要：One of the insecticides of choice to control the mosquito Culex pipiens fatigans, a vector of Bancroftian filariasis, is fenthion. The mechanism of resistance to this insecticide which could develop in C. p. fatigans was investigated in a strain from Rangoon, Burma, made 8 times more fenthion-resistant than normal by laboratory selection, by exposing the larvae to 32P-fenthion and examining the metabolites. Larvae of the resistant strain were found to absorb about half as much fenthion as those of the corresponding normal strain, and they degraded proportionately about twice the amount absorbed to water-soluble metabolites. Thus, the larval content of chloroform-soluble toxicants remaining was only one-third to one-seventh as much in the resistant as in the normal strain. The production of the non-toxic hydrolytic (water-soluble) metabolites was 70% greater in the resistant strain in absolute terms, despite the lower amount absorbed into the larvae. The greatest increase (4-fold) was in the oxonase activity, although the thionase activity was more important in both strains. Esterase zymograms from agar-gel electrophoresis revealed a principal band which was much more intense in the resistant than in the susceptible strain, as judged by its hydrolysis of α- and β-naphthyl acetates and phosphates. This band was comparatively insensitive to the toxicant fenoxon, and could hydrolyse it. Full text Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (1.2M), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References . 401 402 403 404 405 406 406-1 407 408
