Proceeding From in vivo Functions of Pheromone Receptors: Peripheral-Coding Perception of Pheromones From Three Closely Related Species, Helicoverpa armigera, H. assulta, and Heliothis virescens

Abstract

Three closely related species, Helicoverpa armigera, H. assulta, and Heliothis virescens from Lepidoptera Noctuidae, are used as a model system for exploring sexual communication and species isolation. Pheromone receptors (PRs) previously discovered in model moth species include seven in H. armigera, six in H. assulta, and six in H. virescens. PRs named OR6, OR13, and OR16 among these species were found to be functional, characterized by an in vitro Xenopus oocytes system. Using an in vivo transgenic fly system, functional assays of OR6, OR13, and OR16 clades from three closely related Noctuidae species showed that OR13 function was highly conserved, whereas OR6 and OR16 exhibited functional divergence. Similar results were produced from assays in the Xenopus oocytes system. Combined with earlier behavioral results and electrophysiological recordings, we found corresponding relationships among pheromones, PRs, and neurons at the periphery sensory system of each species. Our results provide vital information at the neuronal and molecular level, shedding insight into the sexual communication of closely related species in Lepidoptera.

Review of pheromone receptors in heliothine species: expression, function, and evolution

“…Moreover, the selection of the appropriate expression vector could also be important at least for the Xenopus oocytes expression system (Yang et al, 2017). In general, the PR’s functions reported by studies using different expression systems are well coincided (Grosse‐Wilde et al, 2007; Wang et al, 2011; Wang et al, 2018).…”

“…Although significant progress has been made in the functional analyses of PRs in lepidopteran species, some challenges remain: (1) genetic manipulation tools are very limited compared to D. melanogaster ; (2) gene silencing through RNA interference is difficult to achieve particularly in lepidopteran species (Terenius et al, 2011); and (3) in some cases the results of functional analyses of PRs by using different methods are inconsistent (Wang et al, 2018). We summarize our experiences and put forward some perspectives about the PR’s study in five aspects.…”

“…The Drosophila T1 empty neuron system expresses Drosophila PBPs and SNMPs, which may increase the accuracy in characterizing some PRs’ function (Wang et al, 2016), but the PR genes cannot always be expressed in transgenic fly lines (de Fouchier et al, 2017). As each system has its pros and cons (Wang et al, 2016, 2018; Hou et al, 2019), it would be recommended to use multiple methods in identifying the function of PRs.…”

Comparison of male antennal morphology and sensilla physiology for sex pheromone olfactory sensing between sibling moth species: Ectropis grisescens and Ectropis obliqua (Geometridae)

“…Thus, denser populations of OSNs would not increase their sensitivity when the neurons were in a state of silence. We suggest that larger dendrites could be by‐products of evolution and lack of sensitivity of larger dendrites to the major sex pheromone could be compensated for in other ways; for example, by increasing the concentration of the components surrounding the antennae through the accumulation of chemicals by the scales (Wang, Liu, et al, ; Wang, Shang, et al, ).…”

“…In closely related Helicoverpa moth species, Helicoverpa armigera and Helicoverpa assulta the populations of responding OSNs and the firing frequency of OSNs coincided with the reverse ratios of binary sex pheromone blends (Wu et al, ). Several molecular studies have shown this correspondence is dependent on the expression levels of OR13 and OR6 (Chang et al, ; Jiang, Guo, et al, ; Jiang, Liu, et al, ; Wang, Liu, & Wang, ). The firing frequency of OSNs was not found to be relevant to sex pheromone olfactory coding in E. grisescens and E. obliqua , because the dose‐dependence of OSNs to sex pheromone components was similar in the two species (Figures a–c).…”