Nervous Control of the Mechanical Properties of the Abdominal Wall at Feeding in Rhodnius

Abstract

When larvae of Rhodnius feed, the abdominal wall rapidly becomes extensible. This change is brought about peripherally by the abdominal nervous supply; as a consequence, abdominal segments which have been denervated fail to stretch as much at feeding as do neighbouring innervated segments. The stimulus for this change originates in the head. It appears that the sensations accompanying feeding are responsible and that they have a cumulative effect, so that the degree of plasticization of the abdominal wall depends on the length of time during which the insect has been sucking. Neurosecretory axons are the only known efferent supply to the abdominal wall and so it is most probable that they cause the localized plasticization. The evidence suggests that the plasticization of the abdominal cuticle is a result of an increase in its water content. The increase in plasticity of the abdominal wall is temporary, the effect decreasing progressively after feeding.