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Invasive species pose increasing threats to global biodiversity and ecosystems. While previous studies have characterized successful invaders based on ecological traits, characteristics related to evolutionary processes have rarely been investigated. Here we compared gene flow and local adaptation using demographic analyses and outlier tests in two co-occurring moth pests across their common native range of China, one of which (the peach fruit moth, Carposina sasakii) has maintained its native distribution, while the other (the oriental fruit moth, Grapholita molesta) has expanded its range globally during the past century. We found that both species showed a pattern of genetic differentiation and an evolutionary history consistent with a common southwestern origin and northward expansion in their native range. However, for the noninvasive species, genetic differentiation was closely aligned with the environment, and there was a relatively low level of gene flow, whereas in the invasive species, genetic differentiation was associated with geography. Genome scans indicated stronger patterns of climate-associated loci in the noninvasive species. While strong local adaptation and reduced gene flow across its native range may have decreased the invasiveness of C. sasakii, this requires further validation with additional comparisons of invasive and noninvasive species across their native range.

The peach fruit moth (PFM), Carposina sasakii Matsumura, is a major phytophagous orchard pest widely distributed across Northeast Asia. Here, we report the chromosome-level genome for the PFM, representing the first genome for the family Carposinidae, from the lepidopteran superfamily Copromorphoidea. The genome was assembled into 404.83 Mb sequences using PacBio long-read and Illumina short-read sequences, including 275 contigs, with a contig N50 length of 2.62 Mb. All contigs were assembled into 31 linkage groups assisted by the Hi-C technique, including 30 autosomes and a Z chromosome. BUSCO analysis showed that 98.3% of genes were complete and 0.4% of genes were fragmented, while 1.3% of genes were missing in the assembled genome. In total, 21,697 protein-coding genes were predicted, of which 84.80% were functionally annotated. Because of the importance of diapause triggered by photoperiod in PFM, five circadian genes in the PFM as well as in the other related species were annotated, and potential genes related to diapause and photoperiodic reaction were also identified from transcriptome sequencing. In addition, manual annotation of detoxification gene families was undertaken and showed a higher number of glutathione S-transferase (GST) gene in PFM than in most other lepidopterans, in contrast to a lower number of uridine diphosphate (UDP)-glycosyltransferase (UGT) gene, carboxyl/cholinesterases (CCE) gene and cytochrome P450 monooxygenase (P450) gene, suggesting different detoxication pathways in this moth. The high-quality genome provides a resource for comparative evolutionary studies of this moth and its relatives within the context of radiations across Lepidoptera.

Clarifying the geographic patterns of species diversity and the determinant factors can provide essential information for species conservation and management. Stag beetles (Coleoptera: Lucanidae) of Lucanus are important saproxylic insects and can be used for biomonitoring forests. Most of Lucanus species are facing conservation concerns due to their limited distribution and fragmented habitats, particularly in China, which has the richest species diversity of this genus. The distribution patterns of species diversity of Lucanus at large spatial scales remain portly understood. We studied the distribution patterns of Lucanus and its environmental and geographic determinants in China. Distribution data for 72 species and subspecies were examined. All these species are distributed in southern China except for Lucanus maculifemoratus dybowskyi, which is mainly distributed in north China. The hotspot for Lucanus in China is southeastern Tibet. Our study indicated that the species richness of Lucanus in China was shaped by the precipitation of the wettest and driest month, net primary productivity, digital elevation model, and latitude at a large scale. These variables collectively explained 56.2% of the variation in species richness; precipitation contributed the most (44.1%). Our results provide valuable insights to improve the conservation of Lucanus and can contribute to furthering our understanding of the biogeography of stag beetles in China., We describe the diversity of the stag beetle species and further explore its formation. The result indicated that the variables of geography vegetation, temperature, and precipitation collectively shaped the distributed pattern, and geographical variables are most important.

Aim: A growing number of studies suggest that adaptation of invasive species plays key roles in their successful establishment in novel environments. However, adaptation of invasive species to climatic conditions remains poorly characterized. This study aimed to understand the population genetic structure produced by the cotton mealybug Phenacoccus solenopsis invasion and to identify preliminary signals of selection during its range expansion. Location: China. Methods: We examined genetic structure of 11 populations across China using SNPs, microsatellites and a segment of mitochondrial cox1 gene. ADMIXTURE, STRUCTURE and DAPC were used to infer population genetic structure; the dispersal routes were reconstructed by the DIYABC; SNPs potentially related to climate adaptation were identified by using four populations differentiation methods and three environmental association methods. Results: Strong genetic differentiation was found among populations with FST values ranging from 0.097 to 0.640 based on SNPs. Populations located at the northern expansion edge exhibited the highest genetic differentiation and the lowest genetic diversity. Demographic analyses indicated that all populations were introduced from a single source population with small effective size and low recent gene flow. RDA analysis showed that climatic variables explained a higher proportion of genetic variance (43%) compared to population structure variables (15%). The top climatic variables associated with genetic differentiation were precipitation of the mean temperature of warmest quarter, mean temperature of driest quarter and isothermality. Genes related to climate candidate SNPs were mainly enriched to pathways of development, energy and xenobiotic metabolisms. Main conclusions: We found that extremely rapid and strong population genetic differentiation among populations appears to have developed after introduction in the cotton mealybug. Our study points to rapid neutral evolution and suggests possible climatic adaptation despite low genetic diversity in this invasive species.

Biological invasions of pests into climatically unsuitable areas can be facilitated by human‐regulated environments, in which case there may be an impact on genetic structure through population processes and/or adaptation. Here, we investigated the population genetic structure of an invasive agricultural pest, Thrips palmi, in China, which has expanded its distribution range through using greenhouses. Early invaded populations showed a relatively higher level of genetic diversity than recently expanded greenhouse populations. Strong population genetic structure corresponded to a pattern of isolation by distance, with no recent gene flow and low historical gene flow among populations, reflecting limited ongoing dispersal. A genetic signature of population expansion was detected in early invaded populations and three northern populations from greenhouses, suggesting that the greenhouse environments facilitated expansion of this species. Redundancy analysis showed that the independent effects of environment and geography could explain 51.68% and 32.06% of the genetic variance, respectively. These findings point to climate‐ and greenhouse‐related spatial expansion, with the potential for adaptation by T. palmi. They emphasize the contribution of human‐regulated environments on the successes of this invasive species, a situation likely to apply to other invasive species that use greenhouse environments.

Pest species are often able to develop resistance to pesticides used to control them, depending on how rapidly resistance can emerge within a population or spread from another resistant population. We examined the evolution of bifenazate resistance in China in the two‐spotted spider mite (TSSM) Tetranychus uticae Koch (Acari: Tetranychidae), one of the most resistant arthropods, by using bioassays, detection of mutations in the target cytb gene, and population genetic structure analysis using microsatellite markers. Bioassays showed variable levels of resistance to bifenazate. The cytb mutation G126S, which confers medium resistance in TSSM to bifenazate, had previously been detected prior to the application of bifenazate and was now widespread, suggesting likely resistance evolution from standing genetic variation. G126S was detected in geographically distant populations across different genetic clusters, pointing to the independent origin of this mutation in different TSSM populations. A novel A269V mutation linked to a low‐level resistance was detected in two southern populations. Widespread resistance associated with a high frequency of the G126S allele was found in four populations from the Beijing area which were not genetically differentiated. In this case, a high level of gene flows likely accelerated the development of resistance within this local region, as well as into an outlying region distant from Beijing. These findings, therefore, suggest patterns consistent with both local evolution of pesticide resistance as well as an impact of migration, helping to inform resistance management strategies in TSSM.

Aim To establish patterns of genetic variation associated with the well-documented history of invasion and expansion of the fall webworm (FWW), Hyphantria cunea, into China. Patterns are expected to be affected by geographical and environmental factors as well as a history of control campaigns. Location Northern and eastern China. Methods We genotyped 18 polymorphic microsatellite loci derived from 657 individuals (25 populations) collected from across the distribution range of FWW in China and a native population in USA, and we also sequenced mitochondrial DNA from a subset of 70 individuals. Population genetic structure was analysed by using three Bayesian cluster methods (structure, geneland and tess) and a multivariate principal component analysis (PCA). The scenarios of invasion history were tested using an approximate Bayesian computation (ABC) approach. A multiple matrix regression was performed to assess the relative contributions of geographical and environmental isolation. Results The average allelic richness and mitochondrial haplotype diversity of the FWW populations in China was very low compared to native populations from USA, pointing to a significant bottleneck during colonization. Based on the nuclear markers, two genetically separated groups were identified along with a contact zone between them. ABC analyses suggested a single introduction into the east with subsequent westward expansion. Geographic distance was more important than environmental distance in contributing to genetic differentiation, and geographical barriers were likely to have restricted gene flow, with the contact zone occurring in a mountainous area. Main conclusions The combination of genetic data and historical records of the expansion suggests that geographical barriers and control campaigns have affected the formation and persistence of the two genetic groups. Our study points to ways in which genetic differentiation can develop rapidly in an invasive species after its introduction.

The Green Peach Aphid Myzus persicae (Sulzer, 1776) is one of the most destructive pests of cultivated crops worldwide. Spirotetramat is an insecticide with a novel mode of action on aphids and other sucking pests. Here, we studied the effects of spirotetramat on the biology and development of M. persicae under laboratory condition. The results showed that spirotetramat at sublethal doses caused a decrease in nymph survival. However, we did not find sublethal effects on developmental duration of treated aphids or their offspring when exposed to LC5 (0.2736 mg/L), LC15 (0.5163 mg/L) and LC25 (0.7531 mg/L) concentrations. Treatments with LC30 (0.8808 mg/L), LC60 (1.9830 mg/L) and the recommended concentration for field usage (60 mg/L) significantly reduced the longevity and fecundity of adult aphids. Gross fertility was reduced by 65.34%, 81.80% and 86.51% at LC30, LC60 and recommended concentrations, respectively. The most significant feature of spirotetramat is that it induces nonviable nymphs, leading to a significant reduction in adult fecundity. The proportion of nonviable nymphs significantly increased with the concentration of spirotetramat. The gross and net reproductive rates were reduced by 68.91%, 83.97%, 97.25% and 65.61%, 81.94%, 97.10% at LC30, LC60, and recommended concentrations, respectively. The intrinsic rate of increase decreased to 0 when aphids were exposed to the recommended concentration. Our study showed that the reproductive toxicity of spirotetramat should be fully considered when attempting to evaluate the pesticide's action on insects.