OYELEYE, M.O.; CHATTERJEE, J.; ARACENA, J.*; Mississippi University for Women; Mississippi University for Women; Mississippi University for Women: The feeding and searching behavior of fruit flies (Drosophila melanogaster) on patches of sucrose: effects of quinine and substrate color

Fruit flies (Drosophila melanogaster) deprived of food for 24 hours readily feed on 0.25 M sucrose solutions in the laboratory. After feeding, the flies start a local search behavior, characterized by a high turning rate and a low locomotory rate. The purpose of our experiment was to study the effect of quinine, and the color of the substratum on the feeding and searching behavior of the flies. The effect of quinine on feeding behavior was first determined in two-choice tests. Groups of flies foraged freely on patches of solutions containing wells filled with either pure sucrose or a mixture of sucrose and quinine of varying quinine concentrations. The flies showed no preference for pure 0.25 M sucrose solutions over solutions containing 0.11 mM or less quinine in 0.25 M sucrose but pure sucrose was preferred over solutions containing 0.43 mM or more quinine. In experiments run in complete darkness, searching behavior was not affected by the concentration of quinine in the patches and the flies sampled from both pure and mixed solutions regardless of quinine concentration. The searching behavior of the flies was also tested in the light in two-choice tests on arenas with one side containing dried sucrose and the other side dried sucrose with quinine. Each half had a yellow or blue background underneath the dried solutions. The flies showed a preference for yellow only when the concentration of quinine was below the feeding preference. The results suggest that low concentrations of quinine had a stronger effect on the decision to search than on the decision to feed.