Gustatory systems in phytophagous insects are used to perceive feeding stimulants and deterrents and are involved in insect decisions to feed on particular plants. During the process, gustatory receptors (Gr) can recognize diverse phytochemicals and provide a molecular basis for taste perception. The silkworm, as a representative Lepidoptera species, has developed a strong feeding preference for mulberry leaves. The mulberry-derived flavonoid glycoside, isoquercetin, is required to induce feeding behaviours. However, the corresponding Gr for isoquercetin...