Yinliang Wang

Phylogeny and acoustic signal evolution of a pure tone song katydid Pseudophyllus titan (Orthoptera: Tettigoniidae) based on the complete mitogenome

Abstract Ensifera is an extremely diverse group in the order Orthoptera, and it has been the subject of considerable research, especially in terms of phylogeny and bioacoustics. Katydids are known for using high-frequency broadband signals whereas most cricket songs are pure tones with a frequency range of 2–8 kHz. Pseudophyllus titan is a special katydid emits low-frequency pure tone songs similar to that of crickets. Acoustic communication of Ensifera were widely studied, but song evolution could deserve new examination taking into account the newly available phylogenies. To examine the song evolution of P. titan in the Ensifera, the mitogenomes of P. titan and three other ensiferan species (Sphagniana ussuriana, Oecanthus sinensis, Truljalia hibinonis) were obtained by high-throughput sequencing. In addition, the phylogeny of Ensifera was reconstructed including 63 in-group taxa, and the divergence time was further estimated for major ensiferan lineages. Lastly, the evolutions of song frequency were evaluated based on an ancestral character state reconstruction (ACSR). Moreover, we have studied the calling songs of 78 katydids and performed ACSR based on five genes. All phylogeny analyses confirmed that the superfamily Schizodactyloidea was placed basally to the non-grylloid clade. P. titan was in the Pseudophyllinae clade, and this clade had a distant relationship form other lineages in Phaneropteridae. The ACSR showed that P. titan evolved low-frequency pure tone songs independently after ancestors of katydids evolved high-frequency broadband noise. Referring to the geologic time scale, we suggest that the song frequency evolution in the Ensifera to some extent caused by adaptations to the changing habitat under conditions of climate change and plant evolution.

Identification and evolution of olfactory genes in the small poplar longhorn beetle Saperda populnea.

Saperda populnea is a serious pest of poplar and willow trees in the Palaearctic region, causing extensive damage to forests and the lumber industry. Until recently, there is no safe and effective chemical method to control this pest due to the lack of sufficient knowledge on the molecular basis of its olfactory genes, moreover, the evolutionary history of the olfactory gene family in subfamily Lamiinae is still fully unknown. Our RNA sequencing of the antennae of S. populnea identified 43 odorant binding proteins (OBPs), 15 chemosensory proteins (CSPs), 56 odorant receptors (ORs) and 24 inotropic receptors (IRs) in S. populnea. The RT-PCR results showed several genes were expressed in a sex specific manner, suggesting that these genes might play key role in their olfactory-sensing and sex-related behaviors. Further evolutionary studies were performed on these olfactory genes, overall comparison of the Ka/Ks values of orthologous genes in S. populnea and two other Lamiinae species showed three main conclusions: 1. olfactory genes have evolved more rapidly than the non-olfactory genes in the tested long horn beetles; 2. the IR gene family are under a strong purifying selection; 3. the OBPs of Monochamus alternatus evolved more rapidly than the other two species, which is speculated to be correlated with differentiation of selective pressure in different geographic origins. Detailed evolutionary studies on each olfactory genes showed that several OBPs and ORs are under significantly purifying/relaxed selective pressure, and several positive selection sites were also detected, modeling of SpopOR14 and SpopOBP4/5 showed that most of the positive selection sites were distributed at the N-terminus of SpopOR14, while the positive selection sites in SpopOBP4/5 were located in H-bond donors, results suggest that these sites are more likely to be linked with the selectivity of modeled olfactory genes. The research provided a better understanding of the molecular basis and evolutionary history of the olfactory genes in Lamiinae, through elaborating the mechanism whereby amino structural evolution affects specific variants in OBPs and ORs.

Selectivity and ligand-based molecular modeling of an odorant-binding protein from the leaf beetle Ambrostoma quadriimpressum (Coleoptera: Chrysomelidae) in relation to habitat-related volatiles

In this study, the most abundant and antenna-specific odorant-binding protein (OBP) of the elm pest A. quadriimpressum, AquaOBP4, was expressed and purified. The selectivity of AquaOBP4 was investigated by screening against a panel of 40 habitat-relevant compounds. Based on the obtained results, a homologous model of AquaOBP4 was established. This model indicated that AquaOBP4 is highly homologous to DmelOBP LUSH and includes two main binding sites. A docking analysis showed that four of five active ligands bound at Site 1, whereas the other ligand was situated at Site 2. Furthermore, new ligands were docked in the model, and the results of fluorescence-based binding assays of these compounds were highly consistent with the binding conformation and binding affinity predicted by our model. Additionally, three binding odorants derived from elm leaves elicited a strong electroantennogram response and exerted a significant attractive effect on adult A. quadriimpressum. All of the results showed that AquaOBP4 is likely linked to the foraging behavior of A. quadriimpressum. This study provides a new reliable tool for future large-scale compound screenings and revealed several functional chemicals that might aid the development of a better pest management approach for A. quadriimpressum.

Micromorphological differentiation of left and right stridulatory apparatus in crickets (Orthoptera: Gryllidae)

The present study compared micromorphological differentiation of stridulatory apparatus between the functional right tegmen and non-functional left tegmen, analyzed under scanning electron microscope (SEM), among eight Gryllidae species. The results showed that the main differences were found on the length and shape of files and teeth. The length of stridulatory file and teeth number were lower on the left stridulatory apparatus than that on right stridulatory apparatus in all species. However, the ratio between the length of stridulatory teeth and the interval of stridulatory teeth was significantly higher on the left stridulatory apparatus than that on right stridulatory apparatus in Dianemobius fascipes, Polionemobius taprobanensis, Pteronemobius gifuensis, Teleogryllus occipitalis and Oecanthus longicauda. In addition, the length of stridulatory teeth was positively related to number of stridulatory teeth, however, the interval of stridulatory teeth was negatively related to the ratio between the length of stridulatory teeth and the interval of stridulatory teeth for left and right stridulatory apparatus. Our result illustrated that the length of left and right stridulatory file and teeth length could be an effective character to distinguish species. Left stridulatory apparatus was not entirely degraded than right stridulatory apparatus.

The Complete Mitochondrial Genome and Song Evolution of the Monotypic Genus U. Tarbinsky, 1932 (Orthoptera: Tettigoniidae)

Abstract The insect Uvarovites inflatus Uvarov is highly appreciated in China. It is known for its distinctive songs and horn-like forewings and is raised commercially for insect lovers. U. inflatus was previously categorized as part of the monotypic genus Uvarovites; however, there was little molecular evidence to support this taxonomic classification. This study obtained and investigated the mitogenome of U. inflatus, and its songs were characterized and compared with other Ensifera species whose mitogenomes are available. By performing the mitochondrial analysis, we were able to assess the phylogenetic relationships between these species and discuss the evolution of Ensifera calling songs. The mitogenome of U. inflatus is 15,956 bp in length and contains 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and 1 control region. The organization and orientation of the U. inflatus mitogenome are similar to those of other Tettigonioidea species. Phylogenetic analysis based on 13 protein-coding genes showed that the superfamily Tettigonioidea is monophyletic, as are the other six tested subfamilies from Tettigonioidea. Our results also indicated that Grylloidea is monophyletic. A Bayesian relaxed clock analysis showed that the differentiation of U. inflatus and Gampsocleis gratiosa Brunner occurred in the middle Miocene, suggesting that their speciation occurred over a long evolutionary period. The results provide significant support for the establishment of the monotypic genus Uvarovites. Calling song analysis showed that at least two discrete steps of independent evolution occurred during the change from pure tone to broadband noise, and that the ancestor of existing Ensifera was more likely to have emitted pure-tone songs than broadband signals. Together, the mitogenome, molecular clock, and acoustic data allowed us to clarify the taxonomic state of U. inflatus and propose a timeline for the evolution of Ensifera songs.

Acoustic, genetic and morphological variations within the katydid Gampsocleis sedakovii (Orthoptera, Tettigonioidea)

Abstract In an attempt to explain the variation within this species and clarify the subspecies classification, an analysis of the genetic, calling songs, and morphological variations within the species Gampsocleis sedakovii is presented from Inner Mongolia, China. Recordings were compared of the male calling songs and analysis performed of selected acoustic variables. This analysis is combined with sequencing of mtDNA - COI and examination of morphological traits to perform cluster analyses. The trees constructed from different datasets were structurally similar, bisecting the six geographical populations studied. Based on two large branches in the analysis, the species Gampsocleis sedakovii was partitioned into two subspecies, Gampsocleis sedakovii sedakovii (Fischer von Waldheim, 1846) and Gampsocleis sedakovii obscura (Walker, 1869). Comparing all the traits, the individual of Elunchun (ELC) was the intermediate type in this species according to the acoustic, genetic, and morphological characteristics. This study provides evidence for insect acoustic signal divergence and the process of subspeciation.

Application of insect songs in monitoring population density level of Locusta migratoria migratoria (Orthoptera: Acrididae)

BackgroundThe locusts Locusta migratoria migratoria (Orthoptera: Acrididae) is the most destructive agricultural pests worldwide, the population and distribution of L. migratoria migratoria growing rapidly in recent years. It is crucial to find a green, economical way to monitor this insects population for effective control tactics. In this study, acoustic samples were recorded and analyzed under three different density levels of Asian migratory locust L. migratoria migratoria.ResultsThe results showed that the songs of L. migratoria migratoria had a very stable acoustic feature in time domains; then, we used duration of pulse as a tool for identifying and counting the numbers of pulse to classify the population size. After removing the background noises, an automatic density classification and monitoring system was established based on the backpropagation (BP) neural network. The field sample test showed that the accuracy of the density level recognition reached 96.67%.ConclusionsThe results indicated that the calling songs of insects could be an effective character to distinguish population density level of locust plagues, and it could be potentially used as a green and environmental protection solution in monitoring the dynamics of locust plagues and other acoustic agriculture pests.