Insecticide poisoning: Disruption of a possible autonomic function in pupae of Tenebrio molitor

Abstract

Poisoning of pupae of Tenebrio molitor by pyrethroid, carbamate, or organophosphate insecticides was monitored by recording pressure in the hemocoel. The pressure was controlled automatically at around a negative 0.5 kPa value and predictable sharp peak increases in pressure of 0.5–1.0 kPa occurred in bursts. The pressure pulses in Tenebrio pupae were thought to represent the activity of an important autonomic function in insects. Insecticide poisoning increased the frequency of the pressure pulses and their amplitudes as high as 6 kPa in a dose-dependent manner. The pattern in pyrethroid-poisoned pupae was distinctly different from that following carbamate or organophosphorus poisoning. At 12–18 hr after treatment, the pattern of pressure bursts in pupae recovering from poisoning began to resemble the pattern before treatment, with peaks of pressure. In pupae not recovering from poisoning, the pattern was distinctly different, with only single peak pulses of pressure. Thus, it was possible to determine the fate of poisoned pupae after 12 hr.