Changes in the cuticle, ovaries and colleterial glands during the pseudergate and neotenic molt in Kalotermes flavicollis (FABR.) (Isoptera : Kalotermitidae)

Abstract

Through a particular molt, the pseudergates of the lower dry-wood termite Kalotermes flavicollis (Isoptera : Kalotermitidae) can develop into neotenic replacement sexuals. With electron microscopy, we have studied the development of the cuticle and the reproductive organs (ovaries, colleterial glands) during a neotenic molt and compared with those during a molt of pseudergate. Our work confirms Lüscher's results, indicating that the neotonic molt is shorter than the pseudergate molt (6 days vs 7 days). However, apolysis, digestion of endocuticle, and formation of epi- and procuticle are synchronous in the 2 types of molts. In the pseudergates, the ovaries are in previtellogenesis; the colleterial glands show neither secretory units, nor cuticular lining of the glandular lumen. During the pseudergate molt, the ovaries and the colleterial glands do not undergo cytological modifications. During the neotenic molt, vitellogenesis occurs slowly in the ovaries, whereas the colleterial glands develop very rapidly and are functional when ecdysis occurs; the secretory units are differentiated and the cuticle of the glandular lumen is secreted as early as the second day after the beginning of the molt. Therefore, the colleterial glands appear to be a very good marker for the anticipated sexual maturation of the neotenics and seem appropriate for in vitro study of the hormonal regulation of the neotenic differentiation.