Age-dependent switched taste behavior to ribose.

Chemical detection is vital for animal survival, aiding in avoiding toxins and selecting nutritious foods. While Drosophila larvae exhibit appetitive feeding behavior toward ribose, an important sugar for RNA, nucleotide, and nucleoside synthesis, how adult Drosophila perceives ribose remains unclear. Through behavioral and electrophysiological investigations, we unexpectedly discovered that adult flies actively avoid ribose. Our external electrophysiological analysis revealed that ribose is detected through bitter-sensing gustatory receptor neurons in S-type sensilla, suggesting its perception as a bitter compound. Additionally, we identify painless as crucial for both ribose aversion and the neuronal response to ribose.