Abdominal stretch reception in Dipetalogaster maximus (Hemiptera: Reduviidae)

Each half abdominal segment in 5th-instar larvae of the giant bloodsucking reduviid, Dipetalogaster maximus, contains 3 stretch receptor neurones, one associated with the tergosternal muscles, one with the ventral intersegmental muscles and one with the dorsal intersegmental muscles. Each of the three receptors respond phasically to the onset of stretch in its respective muscle group, but none show persistent activity upon prolonged stretch. By contrast, stretch of the main abdominal nerves (which run between the thoracic ganglion and the ventral intersegmental muscles of each abdominal segment) is accompanied by a prolonged and sustained pattern of discharge by an as yet unidentified neurone, the rate of discharge being proportional to the degree of stretch. In life, the abdominal nerves become stretched to about 145% of their resting length when the larva takes a bloodmeal. Thus it appears that in Dipetalogaster stretch of the abdominal nerves themselves is the only mechanism for stretch reception after a blood meal.