Pharmacological analysis of the feeding response of codling moth (Cydia pomonella; Lepidoptera: Tortricidae) neonates to bitter compounds

Feeding in codling moth neonate caterpillars was inhibited by 0.67 mM and 2.24 mM concentrations of denatonium benzoate. This inhibitory effect was abolished by phospholipase C inhibitor, U-73122 and the phosphodiesterase inhibitor, Rolipram. Quinine and quinidine did not have inhibitory effects at concentrations as high as 1.64 mM and 0.43 mM, respectively. The inhibitory effect of denatonium was partially reversed in the presence of the calcium ion chelator, EGTA, at concentrations ranging from 2.5 µM to 250 µM. These results indicate that transduction of the taste of denatonium in codling moth neonates relies on signalling pathways that involve phospholipase C, phosphodiesterase and calcium ion influx into cells.