THE BEHAVIOR OF SYMPATRIC CHILEAN POPULATIONS OF DROSOPHILA LARVAE DURING PUPATION

The behavioral mechanisms by which the larvae of sympatric Chilean pop ulations of Drosophila melanogaster, D. simulans, D. hydei and D. busc kii select pupation sites are described in terms of larval substrate p references. These species share the same breeding sites in Central Val ley of Chile. It is important to investigate larval substrate preferen ces to pupate in sympatric natural populations of species of Drosophil a because such behavior could contribute to the coexistence of the spe cies in the wild. D. busckii larvae preferred humid substrates with a smooth surface to pupate, whereas D. simulans larvae selected humid su bstrates with a rough surface. Larvae of D. melanogaster chose dry and humid substrates with a rough surface, whereas D. hydei larvae occupi ed dry substrates with a smooth surface to form puparia. D, melanogast er larvae dug deeper into dry than into humid sand, whereas D, simulan s larvae dug more into humid sand. D. busckii larvae pupated in the up per layers of humid and dry sand, and D. hydei larvae dug more into hu mid than into dry sand. Pupae of the four Drosophila species showed ag gregated distributions on the substrates. Larval prepupation behaviors of D, melanogaster, D. simulans, D. hydei and D, busckii could be imp ortant to their coexistence in the wild.