Climate change is predicted to alter the geographic distribution of a wide variety of taxa, including insects. Icerya aegyptiaca (Douglas) and I. purchasi Maskell are two polyphagous and invasive pests in the genus Icerya Signoret (Hemiptera: Monophlebidae) and cause serious damage to many landscape and economic trees. However, the global habitats suitable for these two Icerya species are unclear. The purpose of this study is to determine the potentially suitable habitats of these two species, then to provide scientific management strategies. Using MaxEnt software, the potential risk maps of I. aegyptiaca and I. purchasi were created based on their occurrence data under different climatic conditions and topology factors. The results suggested that under current climate conditions, the potentially habitable area of I. aegyptiaca would be much larger than the current distribution and there would be small changes for I. purchasi. In the future climate change scenarios, the suitable habitats of these two insect species will display an increasing trend. Africa, South America and Asia would be more suitable for I. aegyptiaca. South America, Asia and Europe would be more suitable for I. purchasi. Moreover, most of the highly habitat suitability areas of I. aegyptiaca will become concentrated in Southern Asia. The results also suggested that “min temperature of coldest month” was the most important environmental factor affecting the prediction models of these two insects. This research provides a theoretical reference framework for developing policies to manage and control these two invasive pests of the genus Icerya.

Sirex noctilio F. (Hymenoptera: Siricidae: Siricinae), a new invasive species in China, is a significant international forestry quarantine pest. Transportation of Sirex in logs, and related wood packing materials, has led to environmental damage and substantial economic loss in many countries around the world. Traditional morphological characteristics are not reliable for identification of the Siricidae family, particularly the larvae. Furthermore, specimens are frequently not in a suitable condition to permit morphological identification. The majority of damage is caused by the larval stage, which excavates galleries that can penetrate to the center of tree boles. Thus, development of a rapid, accurate, and effective molecular identification technique for S. noctilio , which does not require expert morphological knowledge, is necessary. Here, we describe a molecular identification tool based on the mitochondrial DNA gene, cytochrome C oxidase subunit I (COI). We designed a species-specific COI (SS-COI) PCR assay, which allows direct identification of S. noctilio , regardless of developmental stage. Six woodwasp species commonly found in China, Sirex noctilio , Sirex nitobei , Sirex sp., Tremex fuscicornis Fabr., Tremex apicalis Matsumura, and Xeris spectrum , were included in our analyses . Moreover, specimens of S. noctilio from 16 different areas were analyzed. The results demonstrate that our molecular assay is effective and accurate, regardless of developmental stage or type of specimen, consistent with use for quarantine purposes, to prevent the harmful consequences of S. noctilio spread.

This study provides the first genetic characterization of the gypsy moth from China ( Lymantria dispar), one of the most recognized pests of forests and ornamental trees in the world. We assessed genetic diversity and structure in eight geographic populations of gypsy moths from China using five polymorphic Inter simple sequence repeat markers, which produced reproducible banding patterns. We observed 102 polymorphic loci across the 176 individuals sampled. Overall genetic diversity (Nei’s, H) was 0.2357, while the mean genetic diversity within geographic populations was 0.1845 ± 0.0150. The observed genetic distance among the eight populations ranged from 0.0432 to 0.1034. Clustering analysis (using an unweighted pair-group method with arithmetic mean and multidimensional scaling), revealed strong concordance between the strength of genetic relationships among populations and their geographic proximity. Analysis of molecular variance demonstrated that 25.43% of the total variability (F_ST = 0.2543, P < 0.001) was attributable to variation among geographic populations. The results of our analyses investigating the degree of polymorphism, genetic diversity (Nei’s and Shannon) and genetic structure, suggest that individuals from Hebei may be better able to adapt to different environments and to disperse to new habitats. This study provides crucial genetic information needed to assess the distribution and population dynamics of this important pest species of global concern.

Sirex nitobei, an Asian native wood wasp species, is a major pest in coniferous commercial forestry, infesting and weakening conifers through its obligate mutualism with a wood-rotting fungus species. The combination of wood wasp larvae and obligate mutualistic fungus causes the breakdown of plant vascular tissue, leading to the weakening of the plant and eventually to death, as well as a high economic cost in commercial forestry. Since it was first recorded in China in the early 1980s, S. nitobei has widely spread and become successfully established. Despite its extensive distribution range, little is known about the factors influencing current and future distribution patterns for potential pest control and monitoring. We used a maximum entropy model in conjunction with climate variables and shared socio-economic pathways to predict the current and future distribution of S. nitobei in China. We used the jackknife method and correlation analysis to select the bioclimatic and environmental variables that influence the geographic distribution of S. nitobei, which resulted in the inclusion of the monthly total precipitation in July (prec7), the monthly average maximum temperature in February (tmax2), the monthly average minimum temperature in July (tmin7), the monthly total precipitation in December (prec12), and isothermality (bio3). We found that precipitation and temperature influenced the potentially suitable areas, as predicted by the maximum entropy model. Moreover, the association of the fungus, the wood wasp, and the host plant impacts are related to availability of moisture and temperature, where moisture affects the growth of the fungus, and temperature influences the emergence, development and growth of larvae. Under the current climate conditions, the total potential suitable areas increased by 18.74%, while highly suitable and moderately suitable areas increased by 28.35 and 44.05%, respectively, under the 2081–2100 ssp245, 370 scenarios. Favorable conditions under climate change, low rainfall, and high temperature will favor the speedy larval development, the growth of its obligate nutritional fungal mutualist and the ability of S. nitobei to rapidly spread in previously unsuitable areas.