Laboratory Testing of Insecticides for Control of the Winter Tick13

Engorged female winter ticks, Dermacentor albipictus (Packard), were dipped in the laboratory in concentrations of 29 insecticides. Then the effects on the estimated reproduction (ER) were determined (ER = g eggs/g ♀ × % hatch of eggs × 20,000), and probit analysis was conducted with percent control of ER afforded by each insecticide. The results are presented in terms of concentrations of insecticides that inhibited the ER of the ticks (IC50 = concentration (%) that inhibited 50% of ER). For the 29 test insecticides, the IC50 values ranged from 0.00013% for isobenzan to 1.933% for ronnel.