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Appearance of highly resistant strain of Culex tritaeniorhynchus to organophosphorus insecticides

1983; Japan Society of Medical Entomology and Zoology; Volume: 34; Issue: 1 Linguagem: Inglês

10.7601/mez.34.33

2185-5609

Kiyoshi Kamimura, Yukiko Maruyama,

Malaria Research and Control

A colony of the larvae of Culex tritaeniorhynchus which was obtained in Toyama Prefecture by laboratory rearing of eggs deposited by wild caught females collected at a pig house surrounded by rice paddies, was shown to be highly resistant to organophosphorus insecticides. The values of LC-50 against malathion, fenitrothion, fenthion, cidial, BPMC, and p, p' DDT were 34,13.5,9.6,8.8,2.16,and 0.078ppm, respectively. It was presumed that repeated applications of organophosphorus insecticides against rice plant pests have resulted in the development of such resistances in this mosquito species, which mainly breeds in rice paddies and is known to be acting as the principal vector of Japanese encephalitis. From analysis of dosage-mortality regression lines of the larvae against malathion and fenitrothion, it was shown that the colony composed of a mixture of different populations with various susceptibility levels against the insecticides. In the study of esterase isozyme patterns of individual female adult mosquitoes reared from larvae that survived after exposure to 5ppm fenitrothion and 10ppm malathion, it was also shown that they were composed of heterologous populations with different active band patterns.