Changes in the escape eliciting system of a cricket revealed by sensory deprivation during postembryonic development

In the air-puff-evoked escape behavior of the cricket Gryllus bimaculatus, the effect of a unilateral cercal ablation and the process of behavioral re covery were investigated during postembryonic development. The response rat e (relative occurrence of the escape behavior in response to an air puff st imulus) and the escape direction (relative to the stimulus direction) in fi rst-, third-, sixth- and last-instar nymphs were almost identical with thos e of adults. A unilateral cercal ablation in the nymphs caused a decrease i n the response rate and an increase in the number of misoriented escapes as have been observed in adults. However, the effect of ablation on the respo nse rate was less in younger insects, i.e., the escape-eliciting potential of one cercus decreased during postembryonic development. Instead, facilita tion of sensory inputs from both cerci essentially occurs, thus explaining the constant response rate throughout the developmental period. The respons e rate of the ablated insects measured after the final molt showed a compen sational increase even when the cercal regenerates were removed at each mol t. Although the final response rate was higher in crickets ablated from ear lier stages, the recovery ratio was larger in crickets ablated from later s tages. Regarding escape direction, a compensational change was observed in insects ablated from the first and the third instars. However, crickets abl ated from the sixth and the last instar did not show any recovery in escape direction. The time course of the recovery in escape direction appears dif ferent between adults and nymphs.