Postembryonic development in the antenna of the cockroach, Leucophaea maderae: Growth, regeneration, and the development of the adult pattern of sense organs

Growth in the antenna of the cockroach, Leucophaea maderae, is achieved through the addition of new segments by the division of the third antennal segment (the meriston) and several segments immediately distal to it. The scape, pedicel, and meriston are all capable of regenerating lost segments. Proximal ablations of the antenna often drive the animal into one or two extra instars. The antennifer region of the head will also regenerate a new antenna after its total amputation, but the insect passes through at least one additional instar before new segments appear. The total number of antennal sensilla increases by a factor of nine times during postembryonic development. Most of the increase is due to the proliferation of olfactory sensilla. Nearly 40% of the total postembryonic increase in sensilla comes at the terminal molt, subsequent to a similarly large increase in antennal surface area in the previous nymphal instar. This finding supports the theory that surface area effects are vital in the differentiation of cuticular sensilla. Evidence from regeneration experiments suggests that the juvenile hormone may also inhibit the differentiation of new olfactory sensilla during the nymphal stages.