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KMID : 0438219750120010319
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Korea University Medical Journal
1975 Volume.12 No. 1 p.319 ~ p.331
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On the Susceptibility of Mosquito Larvae of Anopheles sinensis(Wiedermann), Culex pipiens(Linnaeus) and Aedes vexans nipponii(Theobald) to Various Insecticides
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孫景淳/Son, Kyung Soon
朱仁鎬/車喆煥/Chu, In Ho/Cha, Chul Whan
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Abstract
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The problem of DDT-resistance of body louse began to emerge in 1955 nearly a decade after the introduction of extensive use of DDT especially for the control of epidemic typhus and Japanese B encephalitis and subsequently mosquito larvae of Culex pipiens as well as the house fly also began to show the resistance to DDT, T-BHC and other chlorinated hydrocarbons.
Though in most cases the resistance had not yet presented a checkmate, a search for the substitutes became inevitable.
From 1960 onward Korea has thus substituted, to a large extent, chlorinated hydrocarbon insecticides with organophosphorous compounds such as Parathion, Marathion, Diazinon and DDVP etc.
Apart from the resistance which obviously would make it difficult to control the surviving arthropod population, the issue of the effect of continued use of DDT on environment also became a great concern of many countries and as a result- the public health administration today is inclined to use organophosphorous insecticides.
Korean species of mosquitos have been, therefore, exposed to organophosphorous compounds relatively more heavily than DDT and its related insecticides during the past decade.
This paper describes the degree of mosquito larval susceptibility to various insecticides currently in common use in Korea.
The tests were carried out during the summer of 1970 except the comparative test of susceptibility between Culex pipiens and Culex tritaeniorhynchus which was done in the summer of 1971 Mosquito egg rafts were collected from in and around Seoul city and reared in the laboratory at a temperature of 252C. and a relative humidity.of 8010% in the media made of distilled water 1.0 liter, Magnesium sulfate 1.Og, Calcium sulfate 0.5g and Sodium chloride 0.5g Larval foods were obtained from the Oriental Co., Japan. Twenty to thirty larvae of each species of mosquitos were selected for
the test. These larvae were exposed to various concentrations of insecticides for 24 hours. The number of complete knock-down were counted every 30 minutes, and KT-50 values were computed by the Reed-Muench method.
Insecticides used were DDT, r-BHC, Dieldrin, Malathion and Diazinon. Both emulsions and acetone soultions were prepared in a predetermined series of concentration. The emulsions were prepared with the formulae consisting; the original 1 part, Sorpol H. 770(Japan) 1 part and Xylene 8 parts. All the insecticides were either the product of Baird & McGuire Co., or Barett Co., U. S. A.
The following is the summary of the findings.
1. The mosquito larvae of C:dex pipiens, Anopheles sinensis and Aedes vexans were proved to be susceptible to DDT and other related hydrocarbons while they were quite resistant to organophosphorous compounds.
2. The degree of larval susceptibility to chlorinated hydrocarbons varied with the mosquito species.
Anopheles larvae were the most susceptible followed by Culex pipiens and Aedes vexans in order. There
was no marked difference among the mosquito species in susceptibility to organophosphorous insecti-
cides such as malathion except Aedes vaxans which was substantially more resistant to Diazinon.
3. Insecticide emulsions yielded more knock-down effect to Culex pipiens than that of acetone solutions.
4. KTso values of Culex tritaeniorhynchus were much less than that of Culex pipiens.
5 LCso values of Culex pipiens larvae to DDT and Malathion were 0.02P.p.m. and 0.104P.p.m. respectively which when compared with the result obtained in 1960 show an increase by three to four-fold in resistance to DDT and Malathion.
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