Maakinine is a white crystalline substance, which was first extracted from the bark cortex of a plant. Maaikia amurensis Ruprechet by Kim6 in 1959. This substance is an alkaloid, its m. p. being 155°C, and is easily soluble with water, alcohol and chloroform. Kim pointed out that the pharmacolog cal action of Maakinine is similar to that of nicotin, which fact suggested me to discover any insecticidal action of the substance.
Maakinine powder were prepared at various concentrations of 1. 25, 2. 5 5.0 and 10.0 by adding talcum powder as the carver: The test chemicals were dusted uniformly on the filter paper at a dosage corresponding 3 mg per square centimeter.: Lice were collected from vagrants in.Seoul City. Adult lice and large nymphs of both sexes were used in the experiment. Each lot of 2.0 Lice-was placed into the filter paper. The lice were then confined by placing a. cover dish Both treated and untreated groups were immediately put into an incubator in which a constant temperature of 30° +1° C and relative ,humidity of. 70 % were maintained.
The number of dead individuals were counted at set time intervals. Time mortality data for the lice were summarized in Table 1. From these data the regressionof probit mortality on logarithm of. time, as well as the time required for producing .50 percent mortality (LT-50) were calculated´ as a basis for comparison of efficacy.
From this experiment, I can draw the following conclusions. The median lethal concentrations of the body lice of ´Seoul strain at a dosage of 3 mg per sq. cm, are about 36 minutes by 10 % powder, and about 190 minutes by 1.25 % powder. The results thereby indicate that Maakinine has a drastic knockdown action of lice compared with 24. hours-mortality of lice, Seoul strain with 10 % DDT powder -being: 56.
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