The Characteristics of Chemosensory and Opsin Genes in Newly Emerged and Sexually Mature Agrilus planipennis, an Important Quarantine Forest Beetle

Abstract

The emerald ash borer (EAB), Agrilus planipennis, is a highly destructive quarantine pest. The olfactory and visual systems of A. planipennis play different but critical roles at newly emerged and sexually mature stages; however, the molecular basis underlying these differences remain unclear. Consequently, based on deep transcriptome sequencing, we evaluated the expression levels of chemosensory-related proteins and opsins at the two developmental stages of A. planipennis. We found 15 new chemosensory-related genes in our transcriptome assembly compared with the previous genome assembly, including 6 that code for odorant-binding proteins (OBPs) and 9 for chemosensory proteins (CSPs). The expression of several chemosensory-related genes (OBP7, OBP10, CSP1, and CSP12) differed markedly between newly emerged and sexually mature A. planipennis. We also found that the expression of UV opsin 2 and LW opsin 1 was higher in sexually mature male A. planipennis, which may be associated with their strong visual mate detection ability. This study forms the basis for further investigation of the chemosensory and visual system of A. planipennis, and these differentially expressed genes between newly emerged and sexually mature stages may serve as targets for the management of this destructive forest pest after sexual maturity.

Five Visual and Olfactory Target Genes for RNAi in Agrilus Planipennis

“…Andersson et al (2019) identified twelve OBPs based on the newly analyzed genome of A. planipennis. While we found six new OBPs in our transcriptome assembly (Shen et al, 2021), further improving the data integrity of olfactory related genes identification of EAB.…”

“…So opsins are suitable RNAi targets for insect control and EAB opsin researches have made some progress at present. Lord et al (2016) identified two UV opsins, two LW opsins copies and a partial third LWS opsin copy in the male EAB, and we identified three UV opsins, one UV opsin-like gene, two Green opsins, and two LW opsins in our transcriptome assembly (Shen et al, 2021). Identification of important visual and olfactory genes and the application of RNAi in A. planipennis makes target genes explore feasible in adult EABs.…”

“…Candidate genes were selected based on our previous work (Shen et al, 2021), the selected candidates were expressed significantly different between newly emerged and sexually mature A. planipennis (OBP5, OBP7, OBP10, LW opsin 1 and UV opsin 2) or highly expressed in sexually mature A. planipennis (UV opsin 3). The control consisted injections of dsEGFP (dsRNA against green fluorescent protein), H 2 O and nontreated.…”

The Effect of Trap Color on Catches of Monochamus galloprovincialis and Three Most Numerous Non-Target Insect Species

“…However, insect response/sensitivity to different wavelengths and reflectance intensity seems to be species- and sex-specific [ 30 , 34 , 36 , 37 , 38 ]. Moreover, the recent study of the emerald ash borer Agrilus planipennis Fairmaire (Coleoptera, Buprestidae) showed that immature and mature individuals differ not only in the expression of chemosensory-related genes, but also in the expression of two opsin genes (UV and LW), which may explain the much stronger ability of mature males to visually detect their mates [ 39 ].…”