I'm inclined to agree with you. It also occurred to me that the quinine could be disrupting fly DNA. I don't expect the journalist to detail all the researchers

I'm inclined to agree with you. It also occurred to me that the quinine could be disrupting fly DNA. I don't expect the journalist to detail all the researchers' lab controls but it certainly appears these biologists negligently compared multi-generational quinine exposed flies with a pristine fly colony. If that is true, I hope their paper defended the methodology or significantly hedged the results. In humans, it is usual for small doses of quinine to cause cinchonism. From Wikipedia: "Symptoms of mild cinchonism (which may occur from standard therapeutic doses of quinine) include flushed and sweaty skin, tinnitus, blurred vision, impaired hearing, confusion, reversible high-frequency hearing loss, headache, abdominal pain, rashes, lichenoid photosensitivity, vertigo, dizziness, dysphoria, nausea and vomiting, and diarrhea. Large doses of quinine may lead to severe symptoms of cinchonism: skin rashes, deafness (reversible), somnolence, diminished visual acuity or blindness, anaphylactic shock, and disturbances in cardiac rhythm or conduction, death from cardiotoxicity. Quinine overdose can also result in a rare form of hypersensitivity reaction termed blackwater fever that results in massive hemolysis, hemoglobinemia, hemoglobinuria, and renal failure. In very high doses (higher than those used to treat malaria) during the first trimester of pregnancy quinine may act as an abortifacient, or cause birth defects, especially deafness."