Abstract
As reported in the previous paper (1957), engorged adult female tick, Boophilus caudatus, can not be killed easily even when the maximal dose of γ-BHC is given, but various physiological changes appear with a dose that is much smaller than the lethal dose. Especially, the inhibitory effect of oviposition will make it possible to control the multiplication of ticks.
1. The effects of various insecticides as applied topically, upon the loss of body weight and the oviposition were investigated at 27.5°C and 100% R.H.
2. The percentage of loss of body weight increased abruptly with a dosage of more than 6μg/g of γ-BHC. Parathion, allethrin and TEPP showed a similar tendency in a dosage of more than 6, 100 and 135μg/g, respectively.
3. No loss of body weight was demonstrated in a range of the dosage of the following insecticides; α-BHC (2.82∼35.6mg/g), pp'-DDT (10.0∼1110μg/g), and op'-DDT (100∼3000μg/g).
4. The degree of loss of body weight was almost parallel to the severity of the characteristic symptoms of poisoning, such as wetting and clarification of the cuticle, secretion of watery droplets at certain portions of the cuticular surface, contraction of the dorso-ventral muscles, craniocaudal bending of the body, and decrease of body tension.
5. It was assumed that the loss of body weight was caused by elimination or secretion of water probably according to the activity of the epidermal cell, but this phenomenon disappeared in cases where the higher dosage was applied.
6. In the dosage of such insecticides as γ-BHC, parathion, allethrin and pp'-DDT which caused the loss of body weight, the inhibition of the oviposition of ticks occured. So far as this investigation goes, 3mg/g of op'-DDT and α-BHC partially interrupted the oviposition.
