The physiology of wandering behaviour in XXXX . II. The endocrine control of wandering behaviour.

@entity4079 @entity2338 @entity6372 @entity11088
Removal of the prothoracic glands early during the 5th instar of @entity4079 prevented the larvae from wandering and from further development. Infusion of @entity11088 (20-HE) into these larvae induced wandering behaviour. In intact larvae, induction of precocious wandering behaviour required a 20-HE infusion lasting longer than 5 h. Infused 20-HE induced maximal response (90%) when delivered at a rate of 0.06 micrograms g-1 body weight h-1. At considerably higher concentrations (0.25 micrograms g-1 h-1 larvae performed brief, erratic behaviour or omitted wandering entirely. The latency between appearance of 20-HE and the onset of wandering was dose-dependent with a minimum of 11 h following infusion at 0.1 micrograms g-1 h-1. Latency was not affected by the duration of 20-HE infusion. The duration of induced wandering behaviour was proportional to the duration of 20-HE infusion. Minimal wandering behaviour lasted 2 h following 20-HE infusions at 5 h, while infusions lasting 11 h induced 9 h of wandering behaviour. Several lines of evidence suggest that the effects of 20-HE accumulate over time and directly determine the duration of wandering behaviour. Many larvae exhibited a series of temporally distinct locomotor periods following various 20-HE infusion protocols, suggesting that a series of separate exposures to 20-HE can result in corresponding serial bouts of locomotion. @entity6372 to 20-HE appeared to be principally modulated by @entity2338 . Allatectomy of 2nd, 3rd and 4th instar larvae removed @entity2338 ( @entity2338 ) precociously from these stages and was followed several days later by precocious wandering behaviour. Likewise, application of the @entity2338 mimic, EGS, prior to 20-HE exposure or at the start of it, could prevent the behavioural induction. During the 5th instar, 20-HE became increasingly effective in inducing wandering as larvae grew larger than 5 g, the size at which @entity2338 normally begins to disappear from the haemolymph. Allatectomized 5th instar larvae responded directly to 20-HE a day sooner than larvae with normal @entity2338 titres, but before day 2 the effects of 20-HE on wandering behaviour appear to be indirect, requiring a latency greater than 24 h. Several processes, of which the elimination of @entity2338 is the last, appear to be required before 20-HE can induce wandering behaviour.(ABSTRACT TRUNCATED AT 400 WORDS)
