Modelling of the spread of a potential invasive pest,the Siberian moth (Dendrolimus sibiricus) in Europe

Background： The Siberian moth （Dendrolimus sibiricus） （SM） defoliates several tree species from the genera Larix, Piceo and Abies in northern Asia, east of the Urals. The SM is a potential invasive forest pest in Europe because Europe has several suitable host species and climatic conditions of central and northern Europe are favourable for the SM. Methods： This study developed a grid-based spatio-temporal model for simulating the spread of the SM in case it enters Europe from Russia via border stations. The spread rate was modeled as a function of the spatial distribution of host species, climatic suitability of different locations for the SM, human population density, transportation of moth-carrying material, and flying of moths from tree to tree. Results and conclusions： The simulations showed that the SM is most likely to spread in the forests of northeast Belarus, the Baltic countries, and southern and central Finland. Climatic conditions affected the occurrence of the SM more than human population density and the coverage of suitable host species.

Range expansion of the invasive cotton mealybug, Phenacoccus solenopsis Tinsley: An increasing threat to agricultural and horticultural crops in China

The globally invasive cotton mealybug Phenacoccus solenopsis Tinsley,has recently invaded several Chinese regions,and continues to expand its range.This mealybug is a polyphagous insect pest,with at least 200 host plants from 63 families,including cotton,food crops,fruits,ornamental plants,tobacco,and vegetables.Here,we describe the first finding of P.solenopsis in Shandong Province,and investigate the abundances of its natural enemies(predator Coccinella septempunctata L.and parasitoid Aenasius bambawalei Hayat).All three species were detected from ornamental and weed species in Linyi,Shandong,in September 2018,and were positively identified using DNA barcoding.BLAST analysis revealed significant identity(99.38-100%) between sequences of P.solenopsis obtained in this study and those published in the past.This invasive pest represents a major potential threat to agri-horticulture in Shandong,which is a key province of China for production and export of many vegetables,flowers,fruits,and other crops.This mealybug species has a wide range of potential distribution in Shandong and is easily dispersed with agricultural and horticultural transport products.Further monitoring and management strategies are required to limit the spread of this pest species.

First report of the South American tomato leafminer, Tuta absoluta (Meyrick), in China

Tuta absoluta(Meyrick) originated in South America and is one of the most serious pests of tomatoes. It is also known to attack other solanaceous crops, including potato, eggplant, pepper, tobacco, and weedy species such as black nightshade. After accidental introduction into Spain in 2006, this pest spread rapidly throughout Afro-Eurasia and has become a major threat to tomato production worldwide. Here, we report the first record of T. absoluta as an invasive pest in China. It was found in tomato fields in Ili Kazakg Autonomous Prefecture, Xinjiang Uygur Autonomous Region(Ili, Xinjiang), China, and its occurrence was confirmed by both morphological and molecular approaches. In Ili, T. absoluta has been found to attack eggplant, potato, and black nightshade. We found the larvae generally mining and feeding on leaves and boring into tomato fruits, with multiple larvae sometimes observed in a single fruit. Its infestation levels differ among the tomato fields and host species. In all of the surveyed tomato fields, T. absoluta infested 100% of plants. In some of the fields, up to 90% of the eggplant and 100% of the potato plants were infested. Since no natural enemies were found under field conditions, suitable management practices are urgently needed to stop the further spread of this destructive pest in China.

Windborne migration routes of newly-emerged fall armyworm from Qinling Mountains-Huaihe River region,China

The fall armyworm(FAW,Lepidoptera:Noctuidae),Spodoptera frugiperda(J.E.Smith),invaded China in mid-December 2018;since then,it has become a great threat to Chinese agricultural production.Qinling Mountains-Huaihe River region(QM-HRR)is the transitional zone between northern and southern China,an important region for both corn and wheat production.Based on the actual occurrence of QM-HRR invaded by FAW in 2019,daily mean surface air temperature and nocturnal wind conditions at 925 hPa were examined,and migratory routes of FAW moths originated in QM-HRR were modeled by a forward-trajectory-analysis approach.The results indicated that migratory activities of FAW adults emerged in QM-HRR were initiated from late June.The moths from western QM-HRR,where has complex topographic terrain,mainly flied to Ningxia and Inner Mongolia before mid September.However,FAW moths from the eastern QM-HRR primarily engaged in high-altitude northward transport assisted by the prevailing southerly winds before mid August,and the North China Plain was identified as the main destination of FAW.Meanwhile,the migration trajectories of FAW moths had a possibility to reach the Northeast China Plain.From mid August,FAW moths in eastern QM-HRR largely migrated southward and returned to the Yangtze River Valley.This study provides detailed information on the occurrence and migration routes of FAW moths from QM-HRR and will be helpful for early warning and development of integrated pest management strategies for the control of this exotic insect pest.

Bactericera cockerelli(Sulc), a potential threat to China’s potato industry

The potato psyllid Bactericera cockerelli(Hemiptera:Triozidae)has recently emerged as a serious pest of potatoes and other solanaceous crops.It causes direct feeding damage and also vectors Candidatus Liberibacter solanaceaerum(Lso),a pathogen that causes zebra chip disease in potatoes and which potentially costs growers millions of dollars each year.Such producers rely on frequent sprays of pesticides for psyllid control but the results are unsatisfactory and there are negative side effects.The psyllid has spread beyond its native range in southwest US and northern Mexico to Canada,El Salvador,Honduras,Guatemala and Nicaragua via medium to long range dispersal flights perhaps aided by wind currents,and through anthropogenic means.It was accidentally introduced into New Zealand in 2006 and most recently Australia,most likely through the importation of infested plant material.This review summarizes information from studies on the biology,impact and management of B.cockerelli,and highlights the imminent risk of this insect and its associated pathogen invading China,the world’s largest producer of fresh potatoes.Development of risk maps leading to increased surveillance,could prevent or delay an incursion and facilitate early detection or eradication should this occur.Long-term management with Lso-tolerant potato cultivars and psyllid control using the parasitic wasp Tamarixia triozae and other natural enemies should be pursued,rather than depending on synthetic pesticides.

Diversity and surge in abundance of native parasitoid communities prior to the onset of Torymus sinensis on the Asian chestnut gall wasp(Dryocosmus kuriphilus) in Slovenia,Croatia and Hungary

Since the rapid spread of the Asian chestnut gall wasp(ACGW) throughout south-east Europe in the last few years,the possibilities of its control have been increasingly investigated.Due to constraints in available suppression measures in forest stands,biological control is recognized as the most suitable action to lower the abundance of the new invasive pest.Torymus sinensis,as a specialized parasitoid chalcid wasp of ACGW,was introduced to suppress the pest in Italy in 2005,and later in Croatia,Hungary(2014) and Slovenia(2015).We investigated the native parasitoid complex associated with ACGW in Slovenia,Croatia and Hungary over 8 years of sampling.We found 41 species of native parasitoids,eight of which are the first records on ACGW in Europe,adding up to a total of 51 species known to parasitize ACGW.These findings represent a large complex of cynipid-parasitoid fauna.Moreover,the abundance of native parasitoid populations on ACGW have demonstrated a temporal surge between the invasion of a new alien host(ACGW) and the onset of its specialized parasitoid,T.sinensis.Our results indicate that the introduced parasitoid acts as a very successful biocontrol of ACGW,outcompeting native parasitoids.This outcome should be considered as beneficial through the maintenance of ecological balance in affected forest ecosystems.

Prediction of the global potential geographical distribution of Hylurgus ligniperda using a maximum entropy model

Background: Hylurgus ligniperda(Fabricius) is native to Europe but has established populations in many countries and regions. H. ligniperda mainly infests Pinus species, and can cause severe weakness and even death of the host through its boring activity;it can also be a vector of various pathogenic fungi. This study was conducted to investigate the environmental variables limiting the distribution of H. ligniperda and the change trend of its suitable areas under climate change.Results: We used a maximum entropy model to predict the potential geographical distribution of H. ligniperda on a global scale under near current and future climatic scenarios using its occurrence data and environmental variables. The result shows that the areas surrounding the Mediterranean region, the eastern coastal areas of Asia, and the southeastern part of Oceania are highly suitable for H. ligniperda. The environmental variables with the greatest effect on the distribution of H. ligniperda were determined using the jackknife method and Pearson’s correlation analysis and included the monthly average maximum temperature in April, precipitation of driest quarter, the monthly average minimum temperature in December, precipitation of coldest quarter, mean temperature of driest quarter and mean diurnal range.Conclusions: Excessive precipitation in winter and low temperatures in spring had a great effect on the distribution of H. ligniperda. The potential geographical distribution of H. ligniperda was predicted to change under future climatic conditions compared with near current climate conditions. Highly suitable areas, moderately suitable areas and low suitable areas were predicted to increase by 59.99%, 44.43% and 22.92%, respectively, under the2081–2100 ssp245 scenario.

Is there hybridization between 2 species of the same genus in sympatry?——The genetic relationships between Anoplophora glabripennis,Anoplophora chinensis,and putative hybrids

Anoplophora glabripennis(Asian longhorn beetle,ALB)and Anoplophora chinensis(Citrus longhorn beetle,CLB)are native forest pests in China;they have become important international quarantine pests.They are found using the same Salix aureopendula host tree of Cixi,Zhejiang province,China.On this host tree,we collected additional beetles that appeared to be morphologically intermediate between ALB and CLB.By using a stereoscope,we observed that there were several bumps on the base of the elytra,which was inconsistent with ALB,which typically has a smooth elytral base,but was more like CLB,which has numerous short tubercles on the elytral base.Given their sympatry and intermediate morphology,we hypothesized that these may represent ALB×CLB hybrids.We studied the genomic profiles for 46 samples(ALB,CLB,and putative hybrids)using genotyping-by-sequencing(GBS)providing a reduced representation of the entire genome.Employing principal component analyses on the 163 GBS-derived single nucleotide polymorphism data,we found putative hybrids tightly clustered with ALB,but genetically distinct from the CLB individuals.Therefore,our initial hybrid hypothesis was not supported by genomic data.Further,while mating experiments between adult ALB and CLB were successful in 4 separate years(2017,2018,2020,and 2021),and oviposition behavior was observed,no progeny was produced.Having employed population genomic analysis and biological hybridization experiments,we conclude that the putative hybrids represent newly discovered morphological variants within ALB.Our approach further confirmed the advantage of genome-wide information for Anoplophora species assignment in certain ambiguous classification cases.

Biotic resistance limits the invasiveness of the western flower thrips, Frankliniella occidentalis （Thysanoptera： Thripidae）, in Florida

The spread of the western flower thrips, Frankliniella occidentalis （Pergande）, has resulted in the world-wide destabilization of established integrated pest management programs for many crops. It is hypothesized that frequent exposure to insecticides in intensive agriculture selected for resistant populations, which allowed invasive populations in the eastern USA to overcome biotic resistance from the native community of species. Research conducted in Florida to understand the role of biotic factors in limiting the abundance of the western flower thrips is reviewed. Orius spp. （Hemiptera： Anthocoridae） are effective predators that suppress populations of thrips on crop and non-crop hosts in southern and northern Florida. Orius are more effective predators of the western flower thrips than the native flower thrips, E tritici （Fitch） and E bispinosa （Morgan）. The native species are competitors of the western flower thrips. Excessive fertilization and the use of broad-spectrum insecticides in crop fields further enhances populations of the western flower thrips. Interactions with native species clearly limit the abundance of western flower thrips in Florida, but populations are abundant in fertilized crop fields where application of insecticides excludes predators and competitor species.

Genetic relationships of introduced Colorado potato beetle Leptinotarsa decemlineata populations in Xinjiang, China

The Colorado potato beetle （CPB）, Leptinotarsa decemlineata （Say）, is an infamous invasive species worldwide that aggressively attacks potato and other Solanaceae crops. CPB was first found in China in 1993 and has since spread across 2.77 × 105 km2 in Xinjiang Uygur Autonomous Region. To better understand genetic variation and migration patterns, we used seven polymorphic microsatellite loci to elucidate the genetic relationships and gene flow among 10 CPB populations across Xinjiang. （i） Overall low levels of genetic diversity were detected on the entire population in Xinjiang but most of the diversity was retained among populations during invasion. （ii） The mean pairwise FST was low （0.071 ± 0.043） among populations. The genetic differentiation was little （pairwise FST 0.038 ± 0.016） between the five interior populations （Wusu, Urumqi, Jimsar, Qitai and Mulei） and Tacheng population. The six populations might come from the same genetic group via Bayesian clustering and were closely related on a neighbor-joining tree. Combining the history data, the five interior populations may have originated from Tacheng. （iii） Gene flow was frequent, especially among the five interior populations. Individuals from the interior populations could be assigned to Tacheng at higher probabilities （means 0.518 ± 0.127） than vice versa （means 0.328 ± 0.074）, suggesting that the beetle population has spread from the border to the interior in Xinjiang.

Trajectory modeling revealed a southwest-northeast migration corridor for fall armyworm Spodoptera frugiperda(Lepidoptera:Noctuidae)emerging from the North China Plain

The fall armyworm Spodoptera frugiperda,an invasive insect pest native to the Americas,has established populations throughout eastern China.The North China Plain一a key corn-producing area in East China with a unique topography一was invaded by fall armyworm in 2019 and is seriously threatened by this migratory pest.However,the spatiotemporal extent of the migratory movements of fall armyworm from the North China Plain remains poorly understood.Using an air transport-based trajectory modeling approach that incorporates flight behavior,we simulated the potential nocturnal migration trajectories of fall armyworm from the North China Plain based on historical meteorological data from June to October of 2015-2019,and examined the night-time atmospheric conditions associated with their possible flights.The emigration patterns showed monthly variation in the main landing area and common migration direction.The displacement of newly emerged moths from the North China Plain was concentrated in the Northeast China Plain(including Liaoning,Jilin and Heilongjiang provinces)before late summer,after which they were most likely to undertake return flights to the south(especially into Hubei,Anhui and Hunan provinces).This southwest-northeast aerial migration corridor follows the topography of East China and is affected by the East Asian monsoon.These topographic-atmospheric conditions have resulted in the North China Plain becoming a key stopover for fall armyworm populations engaging in multigenerational long-distance migration across East China.These findings contribute to our knowledge of fall army-worm migration and will aid in the implementation of management and control strategies against this highly migratory agricultural pest.