Diminution of feeding response in Helicoverpa armigera by inhibition or silencing of sugar gustatory receptor

Abstract

Gustatory receptor (GR) is one of the essential chemosensory molecules in Lepidopteran pests. GR is involved in sensing several canonical tastes which in turn regulate the diverse behavioral and physiological responses of these insects. In this article, we have evaluated the alteration in feeding response of Helicoverpa armigera by blocking and silencing of sugar-sensing gustatory receptor 9 (HarmGr9). Sf9 cells based assay showed that glucose analogue, Miglitol, can bind to the expressed HarmGr9. This binding might lead to an inhibition of receptor activation and downstream signaling, indicated by reduced intracellular Ca2+ fluorescence. Further, the in-vivo study illustrated the feeding rate reduced on a diet containing miglitol as compared to the larvae fed on the artificial diet. Reduction in feeding rate was prolonged in insects fed on the miglitol containing diet even after switching to the control glucose diet. Competitive cell-based assay and feeding assay, using equimolar glucose and miglitol, also showed an inhibitory effect on HarmGr-9 activation and insect feeding rate. We have observed similar feeding rate reduction in HarmGr9 knockdown in H. armigera larvae. We believe this unique approach of H. armigera feeding response inhibition by blocking the sugar receptor can be further used to develop a novel strategy for agricultural pest management.