Recording of haemolymph pressure pulsations from the insect body surface

Abstract

1. Relative changes in mechanical pressure of insect haemolymph can be directly recorded from the body surface. Semiconductor straingauge transducers sensitive to loads smaller than 1 μg were used to record movements in the nm range. 2. The instrumentation makes it possible to monitor continuously the rhythmic pulsations in haemolymph pressure over periods of several days or weeks. 3. Synchronized recordings with direct hydraulic and indirect contact transducers in one specimen revealed that the contact transducer method could detect the smallest pulsations in haemolymph pressure. 4. The method was applied to various stages of some Coleoptera, Lepidoptera and Diptera during metamorphosis. Hitherto unknown types of pulsations with different frequencies and amplitudes are described. 5. The continuous monitoring of extracardiac pressure pulsations appears to be a suitable method not only for the diagnosis of normal or pathophysiological states, but also for the determination of ecdysial processes and, in particular, for pharmacokinetic studies on the action of insect hormones, drugs or insecticides.