Candidate pheromone receptors of the red-belted clearwing moth Synanthedon myopaeformis bind pear ester and other semiochemicals

Authors: CATTANEO, ALBERTO - Swedish University Of Agricultural Sciences; Walker Iii, William

Submitted to: Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2025
Publication Date: 5/21/2025
Citation: Cattaneo, A.M., Walker III, W.B. 2025. Candidate pheromone receptors of the red-belted clearwing moth Synanthedon myopaeformis bind pear ester and other semiochemicals. Agriculture. 15(10). Article 1112. https://doi.org/10.3390/agriculture15101112.
DOI: https://doi.org/10.3390/agriculture15101112

Interpretive Summary: The red-belted clearwing moth (also known as the apple clearwing), Synanthedon myopaeformis, is a apple pest insect that was recently introduced to North America from its native range in Eurasia and North Africa. The apple clearwing female moth deposits her eggs on the bark of apple trees and the larvae can bore into the bark, which may ultimately result in destruction of the tree. For most insects, including moths, the sense of smell, or olfaction, has a large influence on vital behaviors. Decades of research on the sense of smell of the codling moth has led to innovative odorant-based pest management strategies that target the codling moth's olfactory system. However, relatively little is known about the olfactory capabilities of the apple clearwing. Odorant molecules are detected by a class of proteins known as odorant receptors, and previous research on odorant receptors from different insect species has revealed new knowledge about odorants that mediate critical insect behaviors that may be targeted in pest management programs. Researchers at the USDA-ARS in Wapato, WA, the Swedish University of Agricultural Sciences studied the expression and function of apple clearwing odorant receptors present in the primary olfactory organ of male moths. They discovered odorant receptors hypothesized to detect odorant molecules involved in same-species interactions as well as molecules that originate from the apple tree host. Furthermore, they identified key odorant molecules that activate some of these odorant receptors. These results may drive further research on the role of these odorants in mediating apple clearwing moth behaviors with the aim to develop odorant-based pest management strategies that include insect trapping and disruption of vital behaviors, such as mating or host-seeking.

Technical Abstract: The red-belted clearwing moth Synanthedon myophaeformis is a deleterious pest of apple orchards, wherein the larvae bore tree bark, resulting in reduced fitness and ultimately death. The main control strategies of this pest still rely on the use of pesticides, while alternative agronomic methods for its control coexist, with the application of the main pheromone (Z,Z)-3,13-octadecadien-1-yl acetate. Until now, the molecular bases of the chemosensory systems of the red-belted clearwing moth have been less explored. With the aim to identify novel ligands that may interfere with the behaviour of S. myophaeformis, in this study, we have isolated and functionally characterised some key odorant receptors (ORs) of this moth by selecting paralogues from two main subgroups of the Lepidopteran pheromone receptor (PR) clade: the OR3 subgroup (OR3.1 to OR3.4) and the OR22 subgroup (OR22.1 to OR22.4). We generated transgenic D. melanogaster expressing SmyoORs in ab3A neurons, which we approached by single sensillum recording (SSR). Among these ORs, we deorphanized SmyoOR3.4 to ligands that we have previously identified for orthologues of the codling moth Cydia pomonella, including the pear ester ethyl-(E,Z)-2,4-decadienoate, its methyl ester analogue methyl-(E,Z)-2,4-decadienote, and the unsaturated aldehyde (Z)-6-undecenal. With this approach, we also identified a wide pattern of activation of SmyoOR22.4 to several apple-emitted ligands. Despite the fact that combining SSR with gas chromatography (GC-SSR) did not unveil the activation of the SmyoORs to compounds present in the headspace from apples, GC-SSR unveiled the enhancement of the SmyoOR3.4 spiking at nanogram doses of both pear ester, methyl ester, and (Z)-6-undecenal. For the first time, this study deorphanized ORs from the red-belted clearwing moth and identified ligands as possible semiochemicals to add to the ongoing strategies for the control of this pest.