Effects of insecticides on ticks

Abstract

Though many chemical control measures on ticks which live in pastures or are parasitic on animals are being carried out, the effective dosage on an individual tick still remains to be studied. The topical application method was adopted to assay the dosage to inhibit the development of the adult female tick (average body length of 6.1mm) and the lethal dosage to the detached ticks in various feeding state of Boophilus caudatus. The dosages of γ-BHC, allethrin and pp′-DDT, causing a drop of 50% of feeding ticks in the rapid developing phase, are 2.05, 68.5 and 385μg per tick, respectively. The development of the tick was not influenced by treatment with 1mg of α-BHC. From the inhibitory and lethal dosage, it is supposed that the resistance of engorged ticks to γ-BHC increases about 106 times or more than that of unfed ticks. No correlation is observed between the change of the cuticle thickness and the increase of γ-BHC resistance. Chemical control of ticks will be conducted most efficaciously when they are in an unfed or an earlier feeding state, because unfed ticks are not so resistant to insecticides. © 1957, JAPANESE SOCIETY OF APPLIED ENTOMOLOGY AND ZOOLOGY. All rights reserved.