Chemosensory Receptor Expression in the Abdomen Tip of the Female Codling Moth, Cydia pomonella L. (Lepidoptera: Tortricidae).

Simple Summary: The codling moth, Cydia pomonella, is a major global agricultural pest of apple, pear, and walnut, and its behaviors are largely influenced by taste and smell. Different protein families that function as chemosensory receptors mediate detection of compounds from the environment. Manipulation of codling moth behaviors by using these compounds in orchards has been a successful approach to reduce fruit damage. This approach, however, has largely targeted male behaviors. Since it is the females that lay eggs, which propagate the species, in this report we sought to learn more about female behaviors. Specifically, we examined gene expression of the smell and taste receptors in female codling moth abdomen tip organs involved in egg-laying behaviors. We identified sets of both smell and taste receptor genes expressed in the abdomen tip that are likely candidates to influence egg-laying decisions. We also determined that expression of some of these receptors is increased or decreased after mating. These results increase our knowledge about the genes that can influence female codling moth behaviors. Future research will study the role of individual receptors with the aim of identifying taste and smell compounds that can be used to manipulate female codling moth behaviors in orchards. In insects, the chemical senses influence most vital behaviors, including mate seeking and egg laying; these sensory modalities are predominantly governed by odorant receptors (ORs), ionotropic receptors (IRs), and gustatory receptors (GRs). The codling moth, Cydia pomonella, is a global pest of apple, pear, and walnut, and semiochemically based management strategies limit the economic impacts of this species. The previous report of expression of a candidate pheromone-responsive OR in female codling moth ovipositor and pheromone glands raises further questions about the chemosensory capacity of these organs. With an RNA-sequencing approach, we examined chemoreceptors' expression in the female codling moth abdomen tip, sampling tissues from mated and unmated females and pupae. We report 37 ORs, 22 GRs, and 18 IRs expressed in our transcriptome showing overlap with receptors expressed in adult antennae as well as non-antennal candidate receptors. A quantitative PCR approach was also taken to assess the effect of mating on OR expression in adult female moths, revealing a few genes to be upregulated or downregulating after mating. These results provide a better understanding of the chemosensory role of codling moth female abdomen tip organs in female-specific behaviors. Future research will determine the function of specific receptors to augment current semiochemical-based strategies for codling moth management. [ABSTRACT FROM AUTHOR]

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