Antennae-specific carboxylesterase genes from Indian meal moth: Identification, tissue distribution and the response to semiochemicals

In the olfactory recognition system of insects, carboxylesterases (CXEs) in insect antennae play crucial roles in inactivating the chemical signals. Identification of antennae-specific CXEs provides the molecular basis of odorant degradation and signal inactivation in insects through which potential pest control strategies can be further studied. Although pheromone-based attract-and-kill has been proved to be an effective method to monitor and control Plodia interpunctella, very few reports have focused on the degradation of pheromone as well as the host volatiles and environmental odorants. In the present study, we identified 28 candidate P. interpunctella carboxylesterases (PintCXEs) from our previously reported antennal transcriptome data. Almost all full-length PintCXEs displayed the characteristics of conserved motifs found in other insect CXEs, such as the oxyanion hole residues (Gly-Gly-Ala), the catalytic triad (Ser-Glu-His), and the conserved pentapeptide Gly-X-Ser-X-Gly. Through phylogenetic analysis, two major groups of PintCXEs were identified, including the moth antennal esterases and mitochondrial and cytosolic esterases. Further gene expression profiling revealed that 13 PintCXEs (PintCXE2, PintCXE4, PintCXE9, PintCXE11, PintCXE13, PintCXE15-21, PintCXE25) were highly expressed in antennae, indicating that these PintCXEs were potentially involved in odorant degradation. Among these PintCXEs, PintCXE2, PintCXE4, PintCXE11-12, PintCXE15 and PintCXE17 were male-specific, while PintCXE9, PintCXE13, PintCXE20 and PintCXE25 were highly expressed in female antennae compared with the male antennae. The expressions of PintCXE19 and PintCXE25 were significantly up-regulated by ester treatment, suggesting that they could be involved in degradation of sex pheromone and environment esters. Our results lay a solid foundation for better understanding the olfactory inactivation system of insects. (C) 2019 Elsevier Ltd. All rights reserved.