The gut microbiota of insects has a wide range of effects on host nutrition, physiology, and behavior. The structure of gut microbiota may also be shaped by their environment, causing them to adjust to their hosts; thus, the objective of this study was to examine variations in the morphological traits and gut microbiota of Lymantria xylina in response to natural and artificial diets using high-throughput sequencing. Regarding morphology, the head widths for larvae fed on a sterilized artificial diet were smaller than for larvae fed on a non-sterilized host-plant diet in the early instars. The gut microbiota diversity of L. xylina fed on different diets varied significantly, but did not change during different development periods. This seemed to indicate that vertical inheritance occurred in L. xylina mutualistic symbionts. Acinetobacter and Enterococcus were dominant in/on eggs. In the first instar larvae, Acinetobacter accounted for 33.52% of the sterilized artificial diet treatment, while Enterococcus (67.88%) was the predominant bacteria for the non-sterilized host-plant diet treatment. Gut microbe structures were adapted to both diets through vertical inheritance and self-regulation. This study clarified the impacts of microbial symbiosis on L. xylina and might provide new possibilities for improving the control of these bacteria.

The purpose of this study was to characterize the endogenous cellulase gene MaCel1 of Monochamus alternatus, which is an important vector of Bursaphelenchus xylophilus, a pine wood nematode, which causes pine wilt disease (PWD). In this study, MaCel1 was cloned by rapid amplification of cDNA end (RACE), and its expression analyzed by RT-qPCR (real-time quantitative PCR detecting). A total of 1778 bp of cDNA was obtained. The encoding region of this gene was 1509 bp in length, encoding a protein containing 502 amino acids with a molecular weight of 58.66 kDa, and the isoelectric point of 5.46. Sequence similarity analysis showed that the amino acids sequence of MaCel1 had high similarity with the β-Glucosinolate of Anoplophoraglabripennis and slightly lower similarity with other insect cellulase genes (GH1). The β-D-Glucosidase activity of MaCel1 was 256.02 ± 43.14 U/L with no β-Glucosinolate activity. MaCel1 gene was widely expressed in the intestine of M. alternatus. The expression level of MaCel1 gene in male (3.46) and female (3.51) adults was significantly higher than that in other developmental stages, and the lowest was in pupal stage (0.15). The results will help reveal the digestive mechanism of M. alternatus and lay the foundation for controlling PWD by controlling M. alternatus.

The vectors of pinewood nematode of Bursaphelenchus xylophilus (Steiner & Bührer, 1934) are mainly known as xylophagous beetles. Understanding the composition and distribution of these xylophagous beetles in host pine trees infected by PWN is critical to control the spread of PWN. In this study, we investigated the community structures of the xylophagous beetles in two main host trees in Fujian and Shandong, Pinus massoniana Lamb. and Pinus thunbergia Parl., in different stages of infection. All beetles were collected by dissecting the whole pine trees and then identified by their morphological characteristics and COI genes. The results showed that the diversity of xylophagous beetles was different not only between the two host pine trees but also among the different infection stages. The diversity of P. massoniana xylophagous beetles was significantly higher than that of P. thunbergii, and there were also significant differences in the different stages of PWN infection. In total, Scolytinae was the most common (53.70%), followed by Curculionidae (18.26%), Cerambycidae (16.31%), and Cleridae (6.04%). Monochamus alternatus, the most important vector of PWN, occupied a large niche and showed different aggregation positions during the three infection stages in both host trees. This result might be related to the resistance of bark beetles to host trees and competition with other xylophagous beetles. The community diversity of xylophagous beetles was jointly affected by both the infection stages of PWN and the spatial niche of xylophagous beetles. Knowledge of the diversity and competitive relationships among xylophagous beetles might help regulate the population dynamics of these beetles.

In the development of actual vehicles, manufacturers usually adopt a simplified control strategy to ensure the reliability of the control strategy based on the application scenarios. There are two main working modes for the fuel cell system in fuel cell electric vehicles in China. One is the stepped power type, and the other is the following power type. Therefore, the analysis and comparison of these two typical working modes in the power test of fuel cell electric vehicles helps determine how the fuel cell system works in the actual vehicle and how to choose energy management strategies in different application scenarios. We do the actual tests to explore how the two typical control strategies perform in actual vehicles. These two typical control strategies show different characteristics in the same test. It shows that the energy management strategies should be adopted according to the application scenarios and optimization goals. In the stepped power control strategy, the fluctuation of the fuel cell system and the frequency of starting and stopping are significantly reduced, which is beneficial to the durability of the fuel cell system. Compared with the stepped control strategy, the fluctuation of the output power of fuel cell electric vehicles with the following power control strategy increased significantly. At the same time, a simplified state of charge (SOC) test method is proposed. Due to the particularity of the stepped power control strategy, the change of capacity can be used to replace the change of SOC. For the following power control strategy, the change of electric energy can be used instead of SOC changes.