Molecular basis of quinine-induced feeding suppression in Hyphantria cunea larvae.

BACKGROUND: Feeding behavior in herbivorous insects is profoundly influenced by chemical cues present in their environment, with some compounds serving as deterrents that reduce or completely inhibit feeding. The fall webworm, Hyphantria cunea, is a highly polyphagous lepidopteran pest that poses significant threats to forestry and agriculture because of its broad host range and high reproductive potential. Despite studies on its feeding ecology, the molecular mechanisms underlying its aversive response to bitter compounds remain largely unexplored.

RESULTS: We demonstrate that quinine significantly suppresses feeding in H. cunea larvae. Using calcium imaging and intracellular calcium concentration measurements via a microplate reader, we identified a bitter gustatory receptor, HcGr148, that specifically responds to quinine. Quantitative real-time polymerase chain reaction analysis revealed that HcGr148 is highly expressed in the mouthpart sensory organs and brain. Moreover, RNA interference via injection of double-stranded RNA targeting HcGr148 markedly reduced the sensitivity of the maxillary taste sensilla to quinine.

CONCLUSION: Our findings reveal key components of the bitter taste signaling in H. cunea and shed light on how this pest species discriminates against unpalatable food sources at the molecular level, thereby offering useful insights into bitter taste perception in lepidopterans and suggesting possible avenues for future pest management research. © 2025 Society of Chemical Industry.