Neotenic production in Cryptotermes brevis (Walker): Influence of geographical origin, group composition, and maintenance conditions (Isoptera: Kalotermitidae)

A comparative experiment with groups of mostly brachypterous nymphs of Cryptotermes brevis, originating either in America or Australia, revealed significant differences in neotenic production attributable to termite source, group composition, and/or maintenance conditions (especially those involving timber presentation). The differences were mainly in the time required to respond to being orphaned. Australian groups produced more supernumerary neotenics than American ones, but the latter suffered a higher nymphal mortality during the phase of neotenic production. In both groups approximately the same number of surviving nymphs (plus the neotenic pair) resulted, but the mechanisms for regulating the numbers were different in the two. Apparently the Australian groups allowed a higher expression of the neotenic potential, and regulation (via the killing of supernumary neotenics) occurred after the nymphs had moulted into neotenics. In American groups, regulation (through the killing of differentiating nymphs occurred before the nymphs underwent ecdysis. Neither of the groups apparently could prevent nymphs from becoming determined toward neotenics. The success or failure of maintenance conditions and group composition in simulating the requirements of different termite species for effective operation of the control mechanisms to keep the number of termites moulting into neotenics as low as possible, clearly influences the outcome of such experiments and dictates caution in making species comparisons.