THE DEVELOPMENT OF LARVAL BEHAVIORS IN SYMPATRIC CHILEAN POPULATIONS OF DROSOPHILA-MELANOGASTER AND DROSOPHILA-SIMULANS

The patterns of movement and foraging were investigated in larvae of t he Chilean sympatric species D. melanogaster and D. simulans. Frequenc ies of 'rover', 'sitter' and 'digger' larvae, as well as locomotion an d the angle size of turning were recorded in nutritive and non-nutriti ve environments. In these environments the sibling species differ in f requencies of 'rover', 'sitter' and 'digger' larval phenotypes. There are also differences in these frequencies between the populations of e ach species and across larval age. As development proceeds, the larvae of D. melanogaster and D. simulans become more diverse in their behav iours. Depending on larval age, strain and species, larval locomotion may be: i) similar in the presence and in the absence of food (D. simu lans), ii) lower in yeast suspension than on agar (D. melanogaster), i ii) higher in the presence of food than on agar (D. simulans). The ang le size of larval turning also shows variability which depends on larv al age, strain and species. Statistical significance of the correlatio n between locomotion and turning, and the regression of turning on loc omotion in larvae of D. melanogaster and D. simulans depends on larval age, strain, species and the environment in which the larvae grow.