Dendrolimus spp. are important destructive pests of conifer forests, and Dendrolimus punctatus Walker (Lepidoptera; Lasiocampidae) is the most widely distributed Dendrolimus species. During periodic outbreaks, this species is said to make "fire without smoke" because large areas of pine forest can be quickly and heavily damaged. Yet, little is known about the molecular mechanisms that underlie the unique ecological characteristics of this forest insect. Here, we combined Pacific Biosciences (PacBio) RSII single-molecule long reads and high-throughput chromosome conformation capture (Hi-C) genomics-linked reads to produce a high-quality, chromosomelevel reference genome for D. punctatus. The final assembly was 614 Mb with contig and scaffold N50 values of 1.39 and 22.15 Mb, respectively, and 96.96% of the contigs anchored onto 30 chromosomes. Based on the prediction, this genome contained 17,593 protein-coding genes and 56.16% repetitive sequences. Phylogenetic analyses indicated that D. punctatus diverged from the common ancestor of Hyphantria cunea, Spodoptera litura and Thaumetopoea pityocampa ~ 108.91 million years ago. Many gene families that were expanded in the D. punctatus genome were significantly enriched for the xenobiotic biodegradation system, especially the cytochrome P450 gene family. This high-quality, chromosome-level reference genome will be a valuable resource for understanding mechanisms of D. punctatus outbreak and host resistance adaption. Because this is the first Lasiocampidae insect genome to be sequenced, it also will serve as a reference for further comparative genomics.

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Aphidius gifuensis Ashmaed parasitizes several species of aphids that cause economic damage to globally important crops; however, the mechanism of host location in this species is unclear.Here, we studied the sensory system in A. gifuensis to explore the likely mechanisms of host location that could be useful in the improved application of this species in aphid biological control programs. We used scanning electron microscopy to observe the external morphologies of the sensilla recorded from the entire body of female and male A. gifuensis. We recorded 16-18 segments and five types of sensilla on female antennae, including Böhm bristle, Chaetica sensillum, basiconic sensillum, trichoid sensillum, and placodea sensillum. The male antennae consisted of 18-20 segments, and distribution of sensilla was similar to female antennae with minor differences. No hole on the surface or tip of the sensilla was observed. Interestingly, scattered pores around the TS were found on the entire body of females, but only from the antennae, abdomen, and thoracic legs in males. TS was the most abundant and widely distributed sensillum. Tympana structures were found on antennae and femur of thoracic legs. Antenna cleaner was found on the tibia of propodeum and wing cleaner was found on the tibia of metapedes.Special crevice-shaped structures were found on the abdomen in both sexes, whereas stripshaped structures were found only on the abdomen of females. Possible functions of the sensilla in relation to their morphologies are discussed.

Insect population dynamics are closely related to 'human' ecological and economic environments, and a central focus of research is outbreaks. However, the lack of molecular-based investigations restricts our understanding of the intrinsic mechanisms responsible for insect outbreaks. In this context, the moth Dendrolimus punctatus Walker can serve as an ideal model species for insect population dynamics research because it undergoes periodic outbreaks. Here, high-throughput whole-transcriptome sequencing was performed using D. punctatus, sampled during latent and outbreak periods, to systemically explore the molecular basis of insect outbreaks and to identify the involved non-coding RNA (ncRNA) regulators, namely microRNAs, long noncoding RNAs, and circular RNAs. Differentially expressed mRNAs of D. punctatus from different outbreak periods were involved in developmental, reproductive, immune, and chemosensory processes; results that were consistent with the physiological differences in D. punctatus during differing outbreak periods. Targets analysis of the non-coding RNAs indicated that long non-coding RNAs could be the primary ncRNA regulators of D. punctatus outbreaks, while circular RNAs mainly regulated synapses and cell junctions. The target genes of differentially expressed microRNAs mainly regulated the metabolic and reproductive pathways during the D. punctatus outbreaks. Developmental, multi-organismal, and reproductive processes, as well as biological adhesion, characterized the competing endogenous RNA network. Chemosensory and immune genes closely related to the outbreak of D. punctatus were further analyzed in detail: from their ncRNA regulators' analysis, we deduce that both lncRNA and miRNA may play significant roles. This is the first report to examine the molecular basis of coding and non-coding RNAs' roles in insect outbreaks. The results provide potential biomarkers for control targets in forest insect management, as well as fresh insights into underlying outbreak-related mechanisms, which could be used for improving insect control strategies in the future.

Semanotus bifasciatus (Motschulsky) (Cerambycidae: Coleoptera) is a major forest borer in China, and attractants provide a promising method for the control of this pest. Exploration of the chemosensory mechanisms of S. bifasciatus is important for the development of efficient attractants for this pest. However, little information is available about the olfactory mechanisms of S. bifasciatus. Previous research has indicated that the trapping effects of the same attractant are different between Beijing and Shandong populations of S. bifasciatus. To explore the reasons for this, next-generation sequencing was performed to analyze the antennal transcriptome of both sexes of the two S. bifasciatus populations, and the olfactory-related genes were identified. Furthermore, the expression levels and single nucleotide polymorphisms (SNPs) of the olfactory-related genes between the two populations were compared. We found that the expression levels of odorant binding proteins (OBPs), odorant receptors (ORs), and sensory neuron membrane proteins (SNMPs) in male S. bifasciatus of the Beijing population were obviously lower than those in the Shandong population, and most of the conserved SNPs in OBPs and ORs of the two populations showed more diversity in the Beijing population. Our work provides a foundation for future research of the molecular olfactory mechanisms and pest management of S. bifasciatus, as well as other longhorn beetles.

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.

Aphidius gifuensis is the main enemy of Myzus persieae. While its parasitic rate can be influenced by the hyperparasitoid, Pachyneuron aphidis. As important parts of insects to sense odors from various environments, study of sensilla can lay the foundation of the further study about the parasitic mechanisms, reduce the hyperparasitic rate, and make the most effect usage of A. gifuensis. Here, we give a fundamental study about the morphology of the sensilla on the whole body of male and female P. aphidis. We observed seven main types of sensilla on them totally by using scanning electron microscopy. Including Böhm bristle (BB), chaetica sensilla (ChS), basiconic sensilla (BS), trichoid sensilla (TS), and placodea sensilla (PS), coeleoconica sensilla (CoS), basiconic capitate peg sensilla (BCPS). In addition, TS on antennae can be divided into four subtypes, on wings can be divided into two subtypes. Sensilla were most abundant on the antennae. We observed all types of sensilla on antennae. TS4 was uniporous and PS was multiporous. The other sensilla were nonporous. We did not find sexual dimorphism with regards to sensilla on the antennae except for the location of CoS. In male, CoS situated on the fourth subsegment of flagellum, but on the eighth subsegment in female. In other organs, TS has the largest number. We also found BS on compound eyes and ovipositor, BB on thoracic legs. The possible roles of these sensilla played in life activities are discussed. Our study makes a contribution of the parasitic mechanism of hyperparasitoids.