RESPONSE TO ORPHANING IN 2 NEOTROPICAL TERMITES - ARMITERMES-EUAMIGNATHUS AND EMBIRATERMES-FESTIVELLUS

In this paper we examine the potential of the termites Armitermes euam ignathus Silvestri: 1901 and Embiratermes festivellus (Silvestri, 1901 ) (Isoptera, Termitidae, Nasutitermitinae) to produce neotenics experi mentally. Three nests of the mound-building termite A. euamignathus, f rom the Brazilian cerrado, had their primary queens removed in August 1994. After 12 months, only one mound survived; it had a normal appear ance. In this healthy, orphaned colony we found the primary king, six physogastric nymphoid female replacement reproductives, two ergatoid f emale replacement reproductives, 46 nymphs, several presoldiers, soldi ers, workers, larvae and many eggs. These data show that neotenics in A. euamignathus may originate from both workers and nymphs, but nympho ids are produced in larger numbers. The biometric study of nymphs and nymphoids suggests that these brachypterous neotenics were derived fro m third instar nymphs after a single moult or from four instar nymphs after a reduction of wing bud length. A piece of an E. festivellus nes t with some third instar nymphs, soldiers and workers was kept under l aboratory conditions. After 12 months, the whole experimental subcolon y was examined and appeared to contain two pigmented nymphoid females, two pigmented nymphoid males, only one larva, seven nymphs of the sam e instar, 148 workers, five soldiers and many eggs. These results also indicate the capacity of the termite E. festivellus to produce nympho id neotenics. These neotenic females were laying eggs, but they were n ot physogastric after a year, unlike some nymphoids of the same specie s collected from natural colonies.