Compensatory regeneration of antennae after removal of the distal segment in Riptortus clavatus (Thunberg) (Heteroptera : Alydidae)

In Riptortus clavatus (Thunberg) (Heteroptera : Alydidae), growth and development of cuticular structures were compared between normal antennae and the antennae whose distal (4th) segment had been amputated during the 1st instar. The total length of the remaining 3 segments was 51% of the normal antenna. From the 2nd ecdysis onwards, the 2nd and 3rd segments grew excessively, and after adult emergence, the length of the operated antennae was 84% that of a normal antenna, although a typical 4th segment, separated from the 3rd segment by an intersegmental membrane, never developed. On the new distal (3rd) segment of operated antennae, long fine sensory hairs and grooved pegs, which characterize the normal distal (4th) segment, began to appear at the 2nd ecdysis, and successively increased in number between molts. Thus, when the distal segment was removed, the remaining segments tended to gradually compensate for the loss, both in terms of length and cuticular structures.