THE EFFECT OF INSECTICIDES ON THE ACTION POTENTIALS OF INSECT NERVE

Solutions of 17 insecticides in corn oil were applied to the leg of Periplaneta americana (L), and their effect on the sensory impulses of the crural nerve was determined by means of a preamplifier and cathode-ray oscillograph. DDT, methoxychlor, and DDD induced well-marked trains of repetitive discharge. Aldrin and dieldrin evoked low-voltage trains of repetitive discharge after a latent period of two to four hours. Technical chlordane, heptachlor, α-chlordan, β-chlordan, and toxaphene all showed considerable latent periods before stimulating the action potentials. Lindane rapidly induced the appearance of tiny sets of repeat spikes. The pyrethrins increased the frequency of impulses, while the dinitro compounds increased both the voltage and frequency. Schradan showed no effect, TEPP a transient stimulation, while parathion induced trains of repetitive discharge after a latent period of three hours.