The evolution of opsin genes in five species of mirid bugs: duplication of long-wavelength opsins and loss of blue-sensitive opsins

Abstract

BackgroundColor vision and phototactic behavior based on opsins are important for the fitness of insects because of their roles in foraging and mate choice. Related topics, including the duplication and loss of opsin genes, have been well investigated in insect orders such as Coleoptera, Lepidoptera, Hymenoptera, Odonata and Orthoptera, and the findings have been used to develop pest management strategies involving light trapping. Mirid bugs of Hemiptera, which are pests that cause heavy economic losses, show capacity for color discrimination and phototaxis. However, the opsins in mirid bugs remain uncharacterized. Herein, we examined five species to investigate the evolution of opsins in the family Miridae.ResultsUsing RNA-seq, we identified several contigs showing high identity with opsins, including four contigs inApolygus lucorumand three contigs each inAdelphocoris suturalis,Adelphocoris fasciaticollis,Adelphocoris lineolatusandNesidiocoris tenuis. Phylogenetic analyses indicated that one of these genes clustered with ultraviolet-sensitive (UV) opsins and that the others clustered with long-wavelength (LW) opsins, suggesting that duplication of LW opsins and loss of blue light-sensitive (B) opsins occurred in mirid bugs. The existence of introns in the LW opsins of mirid bugs suggested that the duplication events were DNA based. Both LW1 and LW2 opsins of mirid bugs were found to be under strong purifying selection. The LW1 opsins were significantly more highly expressed than the LW2 and UV opsins.ConclusionsWe identified the opsins of mirid bugs using five selected mirid species as a representative sample. Phylogenetic analyses clustered one of the genes with UV opsins and the others with LW opsins, suggesting the occurrence of LW opsin duplication and B opsin loss during the evolution of mirid bugs. Intron detection suggested that the identified duplication event was DNA based. The evidence of strong purifying selection and the relatively high expression levels suggested that these opsins exhibit fundamental functions in mirid bugs.

Identification and Expression Analysis of G Protein-Coupled Receptors in the Miridae Insect Apolygus lucorum

“…Among Hemiptera, it has been reported in Acyrthosiphon pisum (22), Aphis craccivora (23), Cimex lectularius (24), Diaphorina citri (25), Nilaparvata lugens (26), and Rhodnius prolixus (27). The family Miridae (Hemiptera: Heteroptera), which includes plant bugs, leaf bugs, or grass bugs, is one of the most diverse families of insects, including over 11,000 species in more than 1,300 genera (4,28). It is the largest family of true bugs belonging to Hemiptera and new members of Miridae are being described constantly.…”

Combining visual cues and pheromone blends for monitoring and management of the tarnished plant bug Lygus lineolaris (Hemiptera: Miridae)

“…These differences in reflectance peaks may explain the higher orientation of L. lineolaris toward red than other colors tested in our experiments. A recent study by Xu et al 35 found that mirid bugs have long-wavelength sensitive receptors but have lost the mediumwavelength/blue-sensitive ones, indicating that their visual systems are tuned towards detecting longer wavelengths (red, orange, etc.). However, the reflectance spectra of the traps used in our study show that the yellow and white traps have high reflectance at the longer wavelengths as well as the red traps.…”

Diversity and Evolution of Frog Visual Opsins: Spectral Tuning and Adaptation to Distinct Light Environments

“…We used RELAX to test for relaxation and intensification of selection on the significant partitions identified by CmC. This method has successfully been applied to test for relaxed selection on opsin genes in several lineages including cichlids, bats, butterflies, and mirid bugs ( Gutierrez et al 2018a , 2018b ; Hauser et al 2021 ; Xu et al 2021 ; Mulhair et al 2023 ). The HYPHY models each automatically inferred gene trees with the GTR model, which were rerooted on Ascaphus truei prior to analyses.…”