The imaginal ecdysis of the cricket (Teleogryllus oceanicus)

Summary

• 1. Ecdysis in the cricket is a highly stereotyped, long-lasting (4 h) behavior, which is composed of independently controlled behavioral components (Motor Programs), of which 48 have been described (Table 1).

• 2. Motor programs are recruited in a stereotyped sequence, are active during coincident periods, and terminate when their individual tasks are complete (Figs. 2, 3, and Tables 3, 4).

• 3. Some motor programs are recruited a second time and associate with new sets of concurrently active motor programs. Others areoptional and can be deleted occasionally.Alternative programs are recruited when ecdysis takes place on a horizontal surface, andbackup programs complete tasks failed by earlier programs.

• 4. Bilateral motor program coordination is symmetric, asymmetric, or alternating, and longitudinal is either synchronous or sequential.

• 5. The behavior occurs as discreteBouts of activity separated by periods of quiescence.

• 6. Anterior and posterior motor programs occur during mutually exclusive periods within each bout of activity during the Ecdysial Phase, and this facilitates cooperation between motor programs.

• 7. Ecdysis is further divided into four functionally distinctPhases: (1) Preparatory (2 h) — anchors and loosens the old cuticle, (2) Ecdysial (20 min) — extricates the body, (3) Expansional (1 h) —inflates the new cuticle, and (4) Exuvial (30 min) — ingests the old cuticle to reclaim nutrients.

• 8. The intensity of the behavior varies systematically, peaking during each of the four phases (Fig. 5), and declining during transitional periods.

• 9. Sensory feedback from newly exposed cuticle controls the period of bouts of activity, and produces the peaks in intensity. Feedback of this sort also recruits and terminates motor programs.

• 10. Complete peeling of the old cuticle 2 h before ecdysis does not trigger the behavior, however. After a 2 h delay, motor program recruitment begins, and the behavior progresses about half way to completion of the Ecdysial Phase before becomming arrested.

• 11. Decapitation also fails to disrupt the normal sequence of motor program recruitment, although it does trigger one motor program (peristaltic abdominal waves) when performed at any time during the 4 h ecdysial period.

• 12. The control of ecdysis is accomplished by a multilayered system of motor programs, a longitudinal bout structure, and four functionally distinct phases, in which both central and sensory elements cooperate.