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KMID : 0378019590020010021
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New Medical Journal
1959 Volume.2 No. 1 p.21 ~ p.26
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Studies on the Resistance of Medically Important Arthropods in Korea to Various Insecticides.(A preliminary report)
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Abstract
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The author carried out a series of several resistant tests of lice and house-flies to insecticides from early May to late August 1958, some of the important results so far obtained as of today can be summarized in this preliminary report.
1. Tests on the body lice of the Seoul strain were performed with the procedures described in a book of "Methods for Determining Insects to Insecticides" published at the U.S. Army Environmental Health Laboratory(AEHL), 27 May 1956. Through the tests it was found that 0.1% p,p´-DDT caused 10.4% mortality of lice in 24 hours and 0.05% p,p´-DDT caused 3.3´% mortality in the same hours. This indicates that the body lice of the Seoul strain is highly resistant to DDT insecticides as compared with- the results on the Orlando laboratory normal strain.
2. The mortality of the adult body lice was observed by, exposing lice to various concentration of p,p´-DDT powder for 24 hours. The results indicated 90.9% kill with 20% of p,p´-DDT, 56.5%` kill with 10%, 38.19/0 kill with 5%, 21.81 kill with 2.59 and 3.7% kill with 1.25% A LD-50 was thus computed to he 6.68,, concentration with Bliss´s probit analysis method.
3. The lice were continuously exposed to wool cloth patches in a 50 ml. beaker for 24 hours. The patches were previously dusted with Pyrethrin praparations (US QM Stock No. 51-1-197 Type II) at two different concentrations of 18 mg and 9 mg per square inch, and the mortality rates were counted after 24 hours exposure. The results were as follows: 85.5% kill with 18 mg per square inch; 58.4% kill with 9 mg per square inch. This proved that Pyrethrin preparations are more effective than with the same dose of 10% DDT against the DDT-resistant lice.
4. Resistant tests were made of the house-flies of the Seoul strain with the methods described above book and the 24 hour mortality . was counted after 15 minutes exposure to p,p´-DDT at a rate of 10 mg per sq. ft. The result showed 2.2´6/ mortality rate, which -corresponds with experimental data on No. 2 resistant fly colony at the Orlando laboratory Fla. in U.S.A.
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