The fire ant Solenopsis invicta is a significant pest that was inadvertently introduced into the southern United States almost a century ago and more recently into California and other regions of the world. An assessment of genetic variation at a diverse set of molecular markers in 2144 fire ant colonies from 75 geographic sites worldwide revealed that at least nine separate introductions of S. invicta have occurred into newly invaded areas and that the main southern U.S. population is probably the source of all but one of these introductions. The sole exception involves a putative serial invasion from the southern United States to California to Taiwan. These results illustrate in stark fashion a severe negative consequence of an increasingly massive and interconnected global trade and travel system.

In his or her Perspective, Blumenthal discusses how plants from high-resource habitats are often poorly defended, nutritious, and strongly regulated by enemies. Consequently, these species may benefit the most by entering new habits to escape their natural enemies. This hypothesis predicts that high-resource invasive species may be particularly susceptible to biological control and that increases in resource availability will favor exotic plants.

Plant invasions often involve rapid evolutionary change. Founder effects, hybridization, and adaptation to novel environments cause genetic differentiation between native and introduced populations and may contribute to the success of invaders. An influential idea in this context has been the Evolution of Increased Competitive Ability (EICA) hypothesis. It proposes that after enemy release plants rapidly evolve to be less defended but more competitive, thereby increasing plant vigour in introduced populations. To detect evolutionary change in invaders, comparative studies of native versus introduced populations are needed. Here, we review the current empirical evidence from: (1) comparisons of phenotypic variation in natural populations; (2) comparisons of molecular variation with neutral genetic markers; (3) comparisons of quantitative genetic variation in a common environment; and (4) comparisons of phenotypic plasticity across different environments. Field data suggest that increased vigour and reduced herbivory are common in introduced plant populations. In molecular studies, the genetic diversity of introduced populations was not consistently different from that of native populations. Multiple introductions of invasive plants appear to be the rule rather than the exception. In tests of the EICA hypothesis in a common environment, several found increased growth or decreased resistance in introduced populations. However, few provided a full test of the EICA hypothesis by addressing growth and defence in the same species. Overall, there is reasonable empirical evidence to suggest that genetic differentiation through rapid evolutionary change is important in plant invasions. We discuss conceptual and methodological issues associated with cross-continental comparisons and make recommendations for future research. When testing for EICA, greater emphasis should be put on competitive ability and plant tolerance. Moreover, it is important to address evolutionary change in characteristics other than defence and growth that could play a role in plant invasions.]]>

Tenuazonic acid (TeA) is a natural phytotoxin produced by Alternaria alternata, the causal agent of brown leaf spot disease of Eupatorium adenophorum. Results from chlorophyll fluorescence revealed TeA can block electron flow from Q(A) to Q(B) at photosystem II acceptor side. Based on studies with D1-mutants of Chlamydomonas reinhardtii, the No. 256 amino acid plays a key role in TeA binding to the Q(B)-niche. The results of competitive replacement with [(14)C]atrazine combined with JIP-test and D1-mutant showed that TeA should be considered as a new type of photosystem II inhibitor because it has a different binding behavior within Q(B)-niche from other known photosystem II inhibitors. Bioassay of TeA and its analogues indicated 3-acyl-5-alkyltetramic and even tetramic acid compounds may represent a new structural framework for photosynthetic inhibitors.

Both live plants and dried straw of water hyacinth were applied to a sequential treatment of swine wastewater for nitrogen and phosphorus reduction. In the facultative tank, the straw behaved as a kind of adsorbent toward phosphorus. Its phosphorus removal rate varied considerably with contact time between the straw and the influent. In the laboratory, the straw displayed a rapid total phosphorus reduction on a KH(2)PO(4) solution. The adsorption efficiency was about 36% upon saturation. At the same time, the water hyacinth straw in the facultative tank enhanced NH(3)-N removal efficiency as well. However, no adsorption was evident. This study demonstrated an economically feasible means to apply water hyacinth phosphorus straw for the swine wastewater treatment. The sequential system employed significantly reduced the land use, as compared to the wastewater stabilization pond treatment, for pollution amelioration of swine waste.

This study was designed to understand the effects of the interspecific competition between red imported fire ant, Solenopsis invicta Buren and two native ant species, Pheidole fervens Smith and Monomorium chinense Santschi, by conducting colony interference and individual confrontation tests under laboratory conditions. The colony interference test showed that both native ant species, owing to their numerical advantage, killed the Solenopsis invicta virus-1 (SINV-1)-infected or healthy queens of S. invicta. Significantly less time was required for M. chinense to kill all SINV-1-infected S. invicta compared with the time required to kill the healthy S. invicta. Compared with healthy S. invicta, SINV-1-infected S. invicta spent a longer time eliminating the P. fervens colonies. In confrontation tests, M. chinense killed a significantly higher number of infected S. invicta minors than they did healthy minors, but the number of S. invicta majors (either infected or healthy) killed was substantially less. This study found that the viral infection weakened the competitive ability of S. invicta and made them prone to be eliminated by M. chinense but not by P. fervens.

Pinewood nematode (Bursaphelenchus xylophilus) is an invasive species that causes a destructive forest disease-pine wilt disease. This disease has been prevalent in some countries in Asia since the 1970s. An amplified fragment length polymorphism survey was used to compare the genetic variation of native and invasive nematode populations in China and to examine the changes in genetic diversity during the invasion process. The genetic diversity of Chinese populations was slightly higher than that of American populations. Analysis of groups sampled from different invasive stages in China, showed that no obvious change in genetic diversity. Hence, genetic drift and founder effects are not obvious in the invasion process. Phylogenetic analysis showed that Chinese pinewood nematode populations were closer to Japanese populations than to American populations. On the basis of the genetic relationships among samples, two major invasion pathways in China are suggested. One is from Guangdong to Anhui and Zhejiang, and the other is from Guangdong to Jiangsu and then from Jiangsu to Hubei, Guizhong and Congqing. The results imply that it is important to reinforce both domestic and international quarantine to control the spread of pinewood nematode.

Bemisia tabaci （Gennadius） biotype B is an important pest that have outbreaked and caused severe damage worldwide through the last 20 years. Recent progress in studying mechanisms of its invasion indicates the greater ability of competitive displacement which involves the competition of ecological niche, reproductive interference, the interactions of whitefly and virus with indigenous B. tabaci and other competing herbivores, is the most important factor. The successful invasion and rapid spread is affected by the pesticide resistance. In the meantime,　the ecological environment (such as host, climatic factor, overwintering sites) also affected the invasion of B. tabaci biotype B. Finally the importance of the invasive mechanism of B. tabaci biotype B and potential directions for future research are discussed.]]>

Certain biotypes of the Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) complex cause extensive damage and are important pests and virus vectors in agricultural crops throughout the world. Among the most invasive and well studied are the B and Q biotypes. Recent reports in Shandong Province, China, have indicated that the Q biotype was introduced there in approximately 2005, whereas the B biotype has been established there for approximately 10 yr. Even so, the present distribution of the two biotypes in Shandong has not been examined. The results of this study showed that the B and Q biotypes are both present in Shandong Province based on bar-coding using a approximately 450-base fragment of the mitochondrial cytochrome oxidase I (mtCOI) gene. In addition, a B biotype-specific polymerase chain reaction primer pair that amplifies a approximately 300 bp mtCOI fragment was designed and used to examine the biotype composition of B. tabaci in selected crops from six provincial locations, using the general mtCOI primers as an internal positive control for DNA quality. The results of this study indicated that the Q biotype was the predominant B. tabaci colonizing all of the crops in the study sites examined. This suggests that the Q biotype has displaced the B biotype in Shandong Province of China, which until now was the predominant biotype. This is the first report of the displacement of the B by the Q biotype in field grown crops in China, and in a locale where neither the B nor the Q biotype is native. We hypothesize that this phenomenon may have been exacerbated by the widespread use of neonicotinoid insecticides for whitefly control, given the sustained efficacy thus far of neonicotinoids against the B biotype, and their failure at times to effectively control the Q biotype.

To find out the nutrition characteristics of Brazilian Banana between rhizosphere and bulk soil, we selected three parent materials，determined the nitrogen status of various forms, soil organic carbon content and changes of s oil pH both in the rhizosphere and bulk soil , analyzed their significant difference and relevance. The result is that: Total nitrogen, ammonium, nitrate and alkaline in rhizosphere were 50.7 %、35.9%、36.7 % and 19.3 % higher than that the bulk soil . Soil organic in the rhizosphere was 36.8 % higher and s oil pH was lower by 0.06 units than the average. The nutrition of rhizosphere was higher than bulk soil in three parent materials. And there were significant differences in content of soil total nitrogen, nitrate and organic content between rhizosphere and bulk soil among three parent materials, however, the ammonium and alkaline were significant differences in different parent materials. Ammonium in the rhizosphere and bulk soil was not correlated with other nutrients.

2, sea level rise and eutrophication on the process of biological invasion have been analyzed based on the invasive status of coastal ecosystem. The results indicate that elevated CO2 disturbs the competitive balance between invasive and native species. Sea level rise adjusts the spatial pattern of invasive species and eutrophication of coastal ecosystem promotes further spread of alien species. At last, the research hotspots about interactions between global change and biological invasion in coastal ecosystem are discussed.]]>

Based on 48 years of summer rainfall data,Morlet wavelet analysis was done of the sequence of summer rainfall in Nenjiang and Harbin,on a multi-time scale.Results show that in recent years,the summer rainfall in Harbin displayed the most apparent cyclical variation on a 29-38-year scale,the largest modulus,and the strongest energy;and the summer rainfall in Nenjiang did an obvious cyclical variation on a 19-30-year scale,and its energy value is quite large.Both the two cyclical variations showed a trend of being stronger in energy with the time.Presently,both the summer rainfalls in Nenjiang and Harbin are in a long cyclical period of low-water.It is predicted that in a relatively long period the summer rainfall will be lower than the average of the past 48 years.

Combining literature review, field survey and expert consultation, investigations were carried out of invasive alien species (IAS) in forest, wetland, grassland, desert, inland water and ocean (sea) ecosystems of China. A total of 488 IAS were identified with detailed information collected including name, taxonomy, distribution, origin, location and time first detected or introduced, pathway, hazard, nutrient circumstance, and habits. Of the 488 IAS,265 were plants, 171 animals, 26 fungi, 12 vira, 11 procaryotes and 3 protists. Analysis of the invasion years of the 392 IAS that have specific records reveals that only 31 IAS came in before 1850 and the number of IAS has been increasing steadily since 1850, especially since 1950. During the 60 years after 1950, 209 IAS appeared. Their debuts occurred mainly in the coastal regions and border provinces, like Yunnan Province and Xinjiang Uyghur Autonomous Region, but the stage tends to be moving northward. The percentage of intentional introduction almost equaled to that of unintentional introduction, but the latter has become the primary in recent years. America, Europe and other parts of Asia are the main origins of IAS of China. The number of IAS presents a decreasing trend from coastal towards inland.

A binomial logistic model was established based on RS, GIS and GPS techniques to simulate and predict the distribution of nest-site of Red-crowned Crane (Grus japonensis) in Zhalong National Nature Reserve (ZLNNR), Heilongjiang Province, China. By using the data of present and absent points, a spatial auto-correlation test was conducted to screen the variables for the model. The result showed the factors affected the nest-site selection by Red-crowned Cranes included natural environment factors such as reed height and coverage, and elevation, and disturbance factors such as distance to residential area, density of dykes and roads around the nest. The model was tested through calculating the match coefficients of observed and predicted present/absent data. The correctly classified rate reached to 80.4%. Meanwhile, the model predicted that the suitable habitat for nesting by Red-crowned Crane reached to 223.46 km2, which mainly distributed in the middle and north of ZLNNR. The model prediction basically reflected the suitable nesting habitat distribution, and might provide scientific basis for efficient conservation and management of the nesting habitats, and restoration of key nesting habitats for Red-crowned Crane in ZLNNR.]]>

The extract from the organs above ground of Annual Fleabane(Erigeron annuus) was used to treat the seeds of some crop seeds, we determined the seeds germination, the length of root and seeding height of four crops.The results were as follows:(1) the allelopathic effects of Annual Fleabane does exist.(2) Higher concentration of the water extract of Annual Fleabane could restrain the seed germination and infancy developing, while lower concentration of the water extract could accelerate developing seed of Brassica chinensis var.communis and Lycoperiscum esculetum.

There is a trade-off between nitrogen (N) allocation to photosynthesis and to defence. Invasive species may reduce N allocation to defence because of the absence of natural enemies. Thus, I hypothesised that invasive species may allocate a higher fraction of total leaf N to photosynthesis and have higher light-saturated photosynthetic rate (P(max)) and photosynthetic N-use efficiency (PNUE) than closely related native species. To test these hypotheses, invasive Eupatorium adenophorum and native E. chinense and E. heterophyllum were compared in a limestone shrub. Unlike expectation, the invader did not allocate a higher fraction of leaf N to photosynthesis than the natives. However, it was more efficient in photosynthetic N partitioning than the natives. It partitioned a higher fraction of the photosynthetic N to carboxylation and showed higher use efficiency of the photosynthetic N, while the natives partitioned a higher fraction of the photosynthetic N to light-harvesting components. Total leaf N content was not significantly different among the three studied invasive and native species. For the invader, the higher fraction of leaf N allocated to carboxylation resulted in the higher N content in carboxylation and in both carboxylation and bioenergetics, which led to higher P(max), and therefore to higher PNUE, water-use efficiency, respiration efficiency and apparent quantum yield. These physiological advantages of the invader and its higher leaf area ratio may contribute to its invasiveness.

The mechanisms underlying biological invasions are still not well elucidated. In this study, ecophysiological traits of invasive Eupatorium adenophorum and native E. japonicum were compared at 10 irradiances in field. I hypothesized that the invader may allocate a higher fraction of leaf nitrogen (N) to photosynthesis and have higher light-saturated photosynthetic rate (P(max)) and specific leaf area (SLA) than E. japonicum. The invader had a significantly higher ability to acclimate to high irradiance than E. japonicum, while it showed a similar shade-tolerant ability. The invader indeed allocated a higher fraction of leaf N to photosynthesis than E. japonicum, which, with its high leaf N content (N(A)), resulted in a higher N content in photosynthesis (N(P)), contributing to its higher biochemical capacity for photosynthesis and P(max). However, the invader had a significantly lower SLA than E. japonicum, contributing to its higher P(max) but increasing its area-based leaf construction cost. The abilities to acclimate to a wider range of irradiance and to allocate a higher fraction of leaf N to photosynthesis, and the higher P(max), N(A), N(P) and leaf area ratio may contribute to the invasion of the invader. High SLA is not always necessary for invasive species.

2. Previously, we found that invasive Ageratina adenophora plants increase nitrogen allocation to photosynthesis and reduce allocation to cell walls compared with native Ageratina plants, suggesting a shift from defence to growth in invasive populations. Here, carrying this work forward, we measured construction costs and benefits associated with photosynthesis at light saturation to leaves. We hypothesized that invasive Ageratina populations might employ a quicker return energy-use strategy by increasing light-saturated photosynthetic rates and photosynthetic energy-use efficiency (PEUE) and by decreasing leaf construction costs.3. Faster-growing plants from invasive populations (China and India) had significantly higher leaf nitrogen concentrations and specific leaf areas than plants from native populations (Mexico). Inconsistent with our prediction, leaf construction costs were not significantly different between plants from invasive and native populations, but higher light-saturated photosynthetic rates and in turn higher PEUE resulted in a significantly shorter payback time of construction costs, which allowed plants from invasive populations to grow faster.4. Synthesis. Our results indicate that Ageratina plants from populations in non-native ranges have a distinct quick return energy-use strategy, a high PEUE and a short payback time but not lower construction costs, which might provide a mechanistic explanation for the commonly observed increase in growth when plants are introduced to new parts of the world. To our knowledge, this is the first study to compare energy-use strategy for plants from invasive and native populations of a noxious invasive species. We cannot exclude some alternative hypotheses for these patterns, such as founder effects, but these ecophysiological differences might provide mechanistic insight for how the evolution of decreased allocation to defence may increase growth and competitive ability.]]>

Alternanthera philoxeroides (alligator weed) is an invasive weed that can colonize both aquatic and terrestrial habitats. Individuals growing in different habitats exhibit extensive phenotypic variation but little genetic differentiation in its introduced range. The mechanisms underpinning the wide range of phenotypic variation and rapid adaptation to novel and changing environments remain uncharacterized. In this study, we examined the epigenetic variation and its correlation with phenotypic variation in plants exposed to natural and manipulated environmental variability. Genome-wide methylation profiling using methylation-sensitive amplified fragment length polymorphism (MSAP) revealed considerable DNA methylation polymorphisms within and between natural populations. Plants of different source populations not only underwent significant morphological changes in common garden environments, but also underwent a genome-wide epigenetic reprogramming in response to different treatments. Methylation alterations associated with response to different water availability were detected in 78.2% (169/216) of common garden induced polymorphic sites, demonstrating the environmental sensitivity and flexibility of the epigenetic regulatory system. These data provide evidence of the correlation between epigenetic reprogramming and the reversible phenotypic response of alligator weed to particular environmental factors.

A genetic analysis of nuclear DNA was performed by inter-simple sequence repeat-polymerase chain reaction (ISSR-PCR) technique on 32 populations of Ageratina adenophora, an invasive triploid weed in China. Among the 100 ISSR markers detected, 12 showed genetic variation both within and among the populations. Among the 446 amplified bands, 93.5% were found polymorphic. Most individuals (99%) displayed a unique ISSR fingerprint pattern, which yielded a high level of polymorphism (P o = 93.5%) and genetic diversity (Nei’s H T = 0.2354). The estimates of population variation, based on ISSR-PCR, were high, as measured by the analysis of molecular variance (AMOVA, F ST = 0.3140), the Wright’s F-statistics (G ST = 0.3453), and the Shannon’s information index (H sp = 0.3716). AMOVA revealed 68.6% genetic variation within the populations and 91.2% within the provinces. The Mantel test showed that genetic distance was significantly correlated with geographic distance.]]>

BACKGROUND: The establishment rate of invasive alien insect species has been increasing worldwide during the past century. This trend has been widely attributed to increased rates of international trade and associated species introductions, but rarely linked to environmental change. To better understand and manage the bioinvasion process, it is crucial to understand the relationship between global warming and establishment rate of invasive alien species, especially for poikilothermic invaders such as insects. METHODOLOGY/PRINCIPAL FINDINGS: We present data that demonstrate a significant positive relationship between the change in average annual surface air temperature and the establishment rate of invasive alien insects in mainland China during 1900-2005. This relationship was modeled by regression analysis, and indicated that a 1 degrees C increase in average annual surface temperature in mainland China was associated with an increase in the establishment rate of invasive alien insects of about 0.5 species year(-)(1). The relationship between rising surface air temperature and increasing establishment rate remained significant even after accounting for increases in international trade during the period 1950-2005. Moreover, similar relationships were detected using additional data from the United Kingdom and the contiguous United States. CONCLUSIONS/SIGNIFICANCE: These findings suggest that the perceived increase in establishments of invasive alien insects can be explained only in part by an increase in introduction rate or propagule pressure. Besides increasing propagule pressure, global warming is another driver that could favor worldwide bioinvasions. Our study highlights the need to consider global warming when designing strategies and policies to deal with bioinvasions.

BACKGROUND: The unintentional transport of species as a result of human activities has reached unprecedented rates. Once established, introduced species can be nearly impossible to eradicate. It is therefore essential to identify and monitor locations where invaders are most likely to establish new populations. Despite the obvious value of early detection, how does an agency identify areas that are most vulnerable to new invaders? Here we propose a novel approach by using the

Studies have demonstrated differences in temperature tolerance between two Liriomyza species, L. huidobrensis and L. sativae. To investigate whether the heat shock proteins (Hsps) in the two species have different expression profiles during temperature stress, we cloned hsp90, 70, 60, 40 and 20, and analysed their expression profiles across temperature gradients by real-time quantitative PCR and Western blotting. The results revealed that the number of TATA-box-like elements and A/T-rich insertion/deletions within the 5' UTRs of the hsps are different in the two species. The temperatures for onset (T(on)) or maximal (T(max)) induction of hsp expression in L. huidobrensis were generally 2.5-10 degrees C lower than those in L. sativae, and the T(on) were highly consistent with the temperature limits of the northern boundary of the range of these two leafminer species. These studies confirmed, in terms of gene expression levels, that L. huidobrensis is more cold tolerant than L. sativae, which is more heat tolerant, and suggest that the T(on) (or T(max)) of hsps can represent the differences in temperature tolerance of these two leafminer species, and may be used to determine their natural geographical distribution limits.

Females and males of the rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Erirhinidae), have two elytral color morphs in Texas: the central pattern of their elytra is black (dark morph) or gray (light morph). In southeast Texas, the dark and light females exhibited similar proportions (28.6 and 32.0%, respectively) in populations collected during the spring. In this study, females of the two morphs were collected near rice fields in southeast Texas during April and May 2005. In the laboratory, light females were more active than dark ones. They mated equally successfully with males, irrespective of morph. For females supplied with males for 2 d or kept solitary, and then reared on rice seedlings for 48 d, no significant differences were found between the two morphs in oviposition period, number of eggs deposited, and survival rate. In both morphs, a proportion of mated females did not oviposit throughout the rearing period, implying that a mating experience might be necessary before reproductive development can be initiated. However, oviposition occurred in a proportion of females in which no mating experience could be detected, and their eggs produced larvae, which suggests the probability of existing parthenogenetic females in southeast Texas.

The relationships between plant viruses, their herbivore vectors and host plants can be beneficial, neutral, or antagonistic, depending on the species involved. This variation in relationships may affect the process of biological invasion and the displacement of indigenous species by invaders when the invasive and indigenous organisms occur with niche overlap but differ in the interactions. The notorious invasive B biotype of the whitefly complex Bemisia tabaci entered China in the late 1990s and is now the predominant or only biotype in many regions of the country. Tobacco curly shoot virus (TbCSV) and Tomato yellow leaf curl China virus (TYLCCNV) are two whitefly-transmitted begomoviruses that have become widespread recently in south China. We compared the performance of the invasive B and indigenous ZHJ1 whitefly biotypes on healthy, TbCSV-infected and TYLCCNV-infected tobacco plants. Compared to its performance on healthy plants, the invasive B biotype increased its fecundity and longevity by 12 and 6 fold when feeding on TbCSV-infected plants, and by 18 and 7 fold when feeding on TYLCCNV-infected plants. Population density of the B biotype on TbCSV- and TYLCCNV-infected plants reached 2 and 13 times that on healthy plants respectively in 56 days. In contrast, the indigenous ZHJ1 performed similarly on healthy and virus-infected plants. Virus-infection status of the whiteflies per se of both biotypes showed limited effects on performance of vectors on cotton, a nonhost plant of the viruses. The indirect mutualism between the B biotype whitefly and these viruses via their host plants, and the apparent lack of such mutualism for the indigenous whitefly, may contribute to the ability of the B whitefly biotype to invade, the displacement of indigenous whiteflies, and the disease pandemics of the viruses associated with this vector.

Invasive species pose risks to regional economies and public health as well as imposing serious damage to natural ecosystems. Urban ecosystems are more susceptible to biological invasions than other ecosystems because they are subjected to more frequent human disturbances. Green space acts as important channels for the spread of alien species into urban ecosystems. Risk analysis can be an effective tool used for preventing invasion of alien species. Although various risk analysis systems have been developed for agricultural and forest ecosystems or nature reserves, the domestic effort to manage risks associated with invasive species in urban green spaces has been limited in China. Therefore, there is a pressing need for formulating scientifically sound methods and approaches for risk analysis in this emerging field. Here, we presented a risk analysis system including risk identification, assessment and management for biological invasions in urban green spaces. Based on risk identification for alien species, we established a risk assessment index that consisted of 4 different layers, i.e. object, item, factor, index layers. A total of 26 index parameters were proposed to assess the risk level, which originated from the risks involved in introduction, colonization, spread and damage of alien species in urban green spaces. In addition, methods for index quantification, weight setting, modeling and risk grading were presented. Applying this system, we analyzed the risks of alien pest species potentially attached to trees brought from Japan to China to green landscapes for the 2010 Expo in Shanghai. Our results showed that 7 species posed a high risk (4 insects, 2 plant pathogens, and 1 plant nematode), 10 species a moderate risk (3 insects, 4 plant pathogens and 3 plant nematodes), and other 2 species (1 insect and 1 nematode) a low or extremely low risk. Based on this analysis, risk management measures were suggested to help local policy-makers set priorities for the management of these alien pests. Monitoring did not reveal the presense of any invasive pests during or after the Expo, suggesting that the risk analysis system may have provided an effective tool for preventing the introduction of invasive alien species and effectively ensuring the ecological security of the 2010 Expo, Shanghai, China.

The sycamore lace bug, Corythucha ciliata (Say) (Hemiptera: Tingidae), is an important invasive exotic pest of Platanus (Proteales: Platanaceae) trees in China. The objective of this study was to determine the effects of temperature on C. ciliata in the laboratory so that forecasting models based on heat accumulation units could be developed for the pest. Development and fecundity of C. ciliata reared on leaves of London plane tree (Platanus x acerifolia) were investigated at seven constant temperatures (16, 19, 22, 26, 30, 33, and 36 degrees C) and at a relative humidity of 80% with a photoperiod of 14:10 (L:D). The developmental time was found to significantly decrease with increasing temperature. The developmental time from egg hatching to adult emergence was respectively 47.6, 35.0, 24.1, 20.0, and 17.1 days at the temperatures of 19, 22, 26, 30, and 33 degrees C. C. ciliata could not complete full development at 16 degrees and 36 degrees C. The developmental threshold temperature (C) estimated for egg-to-adult was 11.17 degrees C, with a thermal constant of (K) 370.57 degree-days. Longevity of females was found to be the shortest, 17.7 days at 33 degrees C and the longest, 58.9 days at 16 degrees C, and that of males was the shortest, 19.7 days at 33 degrees C and the longest, 59.7 days at 16 degrees C. Fecundity was the highest at 30 degrees C, being 286.8 eggs per female over an oviposition period of 8.9 days. Female lifetime fecundity was reduced at other temperatures, being the lowest (87.7 eggs per female) at 19 degrees C. The population trend index (I) of C. ciliata was the highest (130.1) at 30 degrees C and the lowest (24.9) at 19 degrees C. Therefore, the optimal developmental temperature for C. ciliata was determined to be 30 degrees C.

The sycamore lace bug, Corythucha ciliata is a new, invasive pest of Platanus trees in China. Although C. ciliata is often subjected to acute low temperatures in early winter and spring in northern and eastern China, the cold tolerance of C. ciliata has not been well studied. The objectives of this study were to determine whether adults of C. ciliata are capable of rapid cold hardening (RCH), and to compare the benefits of RCH vs. cold acclimation (ACC) in the laboratory. When the adult females incubated at 26 degrees C were transferred directly to the discriminating temperature (-12 degrees C) for 2 h, survival was only 22%. However, exposure to 0 degrees C for 4 h before transfer to -12 degrees C for 2 h induced RCH, i.e., increased survival to 68%. RCH could also be induced by gradual cooling of the insects at rates between 0.1 and 0.25 degrees C min(-1). The protection against cold shock obtained through RCH at 0 degrees C for 4 h was lost within 1h if the adults were returned to 26 degrees C before exposure to -12 degrees C. Survival at both -12 and -5 degrees C was greater for RCH-treated than for ACC-treated adults (for ACC, adults were kept at 15 degrees C for 5 days), and the lethal temperature (2 h exposure) was lower for RCH-treated than for ACC-treated adults. The results suggest that RCH may help C. ciliata survive the acute low temperatures that often occur in early winter and early spring in northern and eastern China.

Supercooling point (SCP) of female adults of Corythucha ciliata was significantly lower than that of male adults, with an average being -11.49 degrees C and -9.54 degrees C, respectively. Low temperature survival of adults of different ages indicated that there were differences in cold survival ability among age groups of adults. Nonlinear regression analysis found that the response of C. ciliata adults to exposure time under different low temperature regimes (above -5 degrees C) was best fitted by a logistic equation. Both low temperature and exposure time had significant effects on mortality of adults. Temperatures above 5 degrees C did not prevent C. ciliata adults from surviving. C. ciliata was shown to be a freeze-intolerant but chill-tolerant insect. C. ciliata could tolerate subzero temperatures by supercooling. Temperature around -8 degres C is a critical point for successful overwintering of C. ciliata adults, which can establish in the whole areas where Platanus trees are planted in China.

Many Liriomyza species are pests of agricultural and ornamental plants. In the past two decades, the occurrence and distribution of certain Liriomyza species have changed dramatically, leading to an extensive body of research papers. First, we review the association of thermal tolerance with population dynamics, geographic distribution, and species displacement. Differences in thermal tolerances between species result in their differential geographic locations and overwintering ranges. Displacements among Liriomyza species are associated with their temperature adaptation. We examine the chemical linkage of plants, Liriomyza, and their parasitoids. Chemical compounds from host and nonhost plants mediate the behavior of Liriomyza and their parasitoids. Liriomyza and their parasitoids use chemical cues to locate their hosts. Induced compounds can be used as attractants of parasitoids or repellents of Liriomyza. Thus, understanding the thermal tolerances and chemical ecology of Liriomyza may enable researchers to predict geographic distribution and to develop novel control strategies.

Past studies have focused primarily on the effects of invasive plants on litter decomposition at soil surfaces. In natural ecosystems, however, considerable amounts of litter may be at aerial and belowground positions. This study was designed to examine the effects of Spartina alterniflora invasion on the pool sizes and decomposition of aerial, surficial, and belowground litter in coastal marshlands, the Yangtze Estuary, which were originally occupied by two native species, Scirpus mariqueter and Phragmites australis. We collected aerial and surficial litter of the three species once a month and belowground litter once every 2 months. We used the litterbag method to quantify litter decomposition at the aerial, surficial and belowground positions for the three species. Yearly averaged litter mass in the Spartina stands was 1.99 kg m(-2); this was 250 and 22.8% higher than that in the Scirpus (0.57 kg m(-2)) and Phragmites (1.62 kg m(-2)) stands, respectively. The litter in the Spartina stands was primarily distributed in the air (45%) and belowground (48%), while Scirpus and Phragmites litter was mainly allocated to belowground positions (85 and 59%, respectively). The averaged decomposition rates of aerial, surficial, and belowground litter were 0.82, 1.83, and 1.27 year(-1) for Spartina, respectively; these were 52, 62 and 69% of those for Scirpus litter at corresponding positions and 158, 144 and 78% of those for Phragmites litter, respectively. The differences in decomposition rates between Spartina and the two native species were largely due to differences in litter quality among the three species, particularly for the belowground litter. The absolute amount of nitrogen increased during the decomposition of Spartina stem, sheath and root litter, while the amount of nitrogen in Scirpus and Phragmites litter declined during decomposition for all tissue types. Our results suggest that Spartina invasion altered the carbon and nitrogen cycling in the coastal marshlands of China.

Social-economic factors are considered as the key to understand processes contributing to biological invasions. However, there has been few quantified, statistical evidence on the relationship between economic development and biological invasion on a worldwide scale. Herein, using principal factor analysis, we investigated the relationship between biological invasion and economic development together with biodiversity for 91 economies throughout the world. Our result indicates that the prevalence of invasive species in the economies can be well predicted by economic factors (R(2) = 0.733). The impact of economic factors on the occurrence of invasive species for low, lower-middle, upper-middle and high income economies are 0%, 34.3%, 46.3% and 80.8% respectively. Greenhouse gas emissions (CO(2), Nitrous oxide, Methane and Other greenhouse gases) and also biodiversity have positive relationships with the global occurrence of invasive species in the economies on the global scale. The major social-economic factors that are correlated to biological invasions are different for various economies, and therefore the strategies for biological invasion prevention and control should be different.

Increasing levels of global trade and intercontinental travel have been cited as the major causes of biological invasion. However, indirect factors such as economic development that affect the intensity of invasion have not been quantitatively explored. Herein, using principal factor analysis, we investigated the relationship between biological invasion and economic development together with climatic information for China from the 1970s to present. We demonstrate that the increase in biological invasion is coincident with the rapid economic development that has occurred in China over the past three decades. The results indicate that the geographic prevalence of invasive species varies substantially on the provincial scale, but can be surprisingly well predicted using the combination of economic development (R(2) = 0.378) and climatic factors (R(2) = 0.347). Economic factors are proven to be at least equal to if not more determinant of the occurrence of invasive species than climatic factors. International travel and trade are shown to have played a less significant role in accounting for the intensity of biological invasion in China. Our results demonstrate that more attention should be paid to economic factors to improve the understanding, prediction and management of biological invasions.

The volatile oil from C. odorata had a significant effect on the growth of plants, fungi and insects. The result showed that the seedling growth of five test plants was obviously inhibited, in the order of ryegrass > Chinese cabbage > radish > snap been > rice. The inhibitory effect of the oil at its middle concentration (800 mg.L-1) for Pyricularia grisea was the strongest, the next was to Phytophthora nicotianae, and the weakest was to Fusarium axysporum. The inhibitory percentage was 61.40%, 29.27% and 14.44%, respectively. The volatile oil from C. odorata at the dose of 10-20 microliters.plant-1 had a significant oviposition deterrent effect on Phyllotreta striolata and Plutella xylostella. The volatile oil from C. odorata was analyzed by GC/MS and thirty components were identified. Terpenoids compounds were major components of the volatile oil, such as trans-caryophyllene (16.58%), delta-cadinene (15.85%), alpha-copaene (11.58%), caryophyllene oxide (9.63%), germacrene-D (4.96%), and delta-humulene (4.32%).

The ecological effects of plant-virus-vector interactions on invasion of alien plant viral vectors have been rarely investigated. We examined the transmission of Tomato yellow leaf curl China virus (TYLCCNV) by the invasive Q biotype and the indigenous ZHJ2 biotype of the whitefly Bemisia tabaci, a plant viral vector, as well as the influence of TYLCCNV-infection of plants on the performance of the two whitefly biotypes. Both whitefly biotypes were able to acquire viruses from infected plants and retained them in their bodies, but were unable to transmit them to either tobacco or tomato plants. However, when the Q biotype fed on tobacco plants infected with TYLCCNV, its fecundity and longevity were increased by 7- and 1-fold, respectively, compared to those of the Q biotype fed on uninfected tobacco plants. When the ZHJ2 biotype fed on virus-infected plants, its fecundity and longevity were increased by only 2- and 0.5-fold, respectively. These data show that the Q biotype acquired higher beneficial effects from TYLCCNV-infection of tobacco plants than the ZHJ2 biotype. Thus, the Q biotype whitefly may have advantages in its invasion and displacement of the indigenous ZHJ2 biotype.

The role of behavioral mechanisms in animal invasions is poorly understood. We show that asymmetric mating interactions between closely related but previously allopatric genetic groups of the whitefly Bemisia tabaci, a haplodiploid species, have been a driving force contributing to widespread invasion and displacement by alien populations. We conducted long-term field surveys, caged population experiments, and detailed behavioral observations in Zhejiang, China, and Queensland, Australia, to investigate the invasion process and its underlying behavioral mechanisms. During invasion and displacement, we found increased frequency of copulation leading to increased production of female progeny among the invader, as well as reduced copulation and female production in the indigenous genetic groups. Such asymmetric mating interactions may be critical to determining the capacity of a haplodiploid invader and the consequences for its closely related indigenous organisms.

The invasion of water hyacinth (Eichhornia crassipes) has resulted in enormous ecological and economic consequences worldwide. Although the spread of this weed in Africa, Australia, and North America has been well documented, its invasion in China is yet to be fully documented. Here we report that since its introduction about seven decades ago, water hyacinth has infested many water bodies across almost half of China's territory, causing a decline of native biodiversity, alteration of ecosystem services, deterioration of aquatic environments, and spread of diseases affecting human health. Water hyacinth infestations have also led to enormous economic losses in China by impeding water flows, paralyzing navigation, and damaging irrigation and hydroelectricity facilities. To effectively control the rampage of water hyacinth in China, we propose a sustainability science-based management framework that explicitly incorporates principles from landscape ecology and Integrated Pest Management. This framework emphasizes multiple-scale long-term monitoring and research, integration among different control techniques, combination of control with utilization, and landscape-level adaptive management. Sustainability science represents a new, transdisciplinary paradigm that integrates scientific research, technological innovation, and socioeconomic development of particular regions. Our proposed management framework is aimed to broaden the currently dominant biological control-centered view in China and to illustrate how sustainability science can be used to guide the research and management of water hyacinth.

Novel genotypes often arise during biological invasions, but their role in invasion success has rarely been elucidated. Here we examined the population genetics and behavior of the fungus, Leptographium procerum, vectored by a highly invasive bark beetle, Dendroctonus valens, to determine whether genetic changes in the fungus contributed to the invasive success of the beetle-fungal complex in China. The fungus was introduced by the beetle from the United States to China, where we identified several novel genotypes using microsatellite markers. These novel genotypes were more pathogenic to Chinese host seedlings than were other genotypes and they also induced the release of higher amounts of 3-carene, the primary host attractant for the beetle vector, from inoculated seedlings. This evidence suggests a possible mechanism, based on the evolution of a novel genotype during the two or three decades since its introduction, for the success of the beetle-fungal complex in its introduced region.

We studied the changes in wetland habitats and waterbird communities between the 1980s and the 2000s at Chongming Dongtan, a Ramsar site in the Yangtze River estuary, an ecologically important region. This region is an important stopover site for shorebirds along the East Asian-Australasian flyway and is extensively used by waterfowl. A net loss of 11% of the wetland area was estimated during study periods at Chongming Dongtan. The change was dependent on wetland types: while the area of artificial habitats such as paddy fields and aquacultural ponds more than doubled, more than 65% of natural habitats including sea bulrush (Scirpus mariqueter) and common reed (Phragmites australis) marshes were lost over the two decades. An exotic plant species introduced from North America, smooth cordgrass (Spartina alterniflora), occupied 30% of the vegetated intertidal zone by the 2000s. Although waterbird species richness did not change between the 1980s (110) and the 2000s (111), 13 species found in 1980s were replaced by 14 newly recorded species. Moreover, there were more species with declining trends (58) than with increasing trends (19). The population trends of species were affected by residential status and habitat types. Transients, wintering migrants, and habitat specialists were more likely to show declining trends compared to those breeding at Dongtan (including year-round and summer residents) and habitat generalists. Furthermore, species associated mainly with natural wetlands were more likely to decline than those associated mainly with artificial wetlands. These patterns suggest that the loss and change of wetland habitats at Chongming Dongtan adversely affected local population dynamics and might have contributed to the global decline of some waterbird species. Because Chongming Dongtan provides stopover and wintering habitats for many migratory waterbirds, protection and restoration of natural wetlands at Chongming Dongtan are urgently needed.

The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), causes severe crop losses to many crops. The worst of these losses are often associated with the invasion and establishment of biotypes B and Q of this pest. Previous research in 2007 showed that biotype Q occurred with other biotypes in most field populations in China. To determine the current status of the biotype composition in the field, an extensive survey covering mainly eastern parts of China was conducted in 2009. Using polymerase chain reaction primers specific for the mitochondrial cytochrome oxidase I of biotypes B and Q and gene sequencing, we determined the biotypes composition in 61 whitefly populations and their distribution across 19 provinces in China. Our research revealed that only biotypes B and Q have been found in the field in 2009 in China. Among them, biotype Q was dominant in 44 locations (100.0%) and biotype B was dominant in 17 locations (100.0%). The current survey indicates that biotype Q has rapidly displaced biotype B in most locations in China.

BACKGROUND: Tomato yellow leaf curl virus (TYLCV) was introduced into China in 2006, approximately 10 years after the introduction of an invasive whitefly, Bemisia tabaci (Genn.) B biotype. Even so the distribution and prevalence of TYLCV remained limited, and the economic damage was minimal. Following the introduction of Q biotype into China in 2003, the prevalence and spread of TYLCV started to accelerate. This has lead to the hypothesis that the two biotypes might not be equally competent vectors of TYLCV. METHODOLOGY/PRINCIPAL FINDINGS: The infection frequency of TYLCV in the field-collected B. tabaci populations was investigated, the acquisition and transmission capability of TYLCV by B and Q biotypes were compared under the laboratory conditions. Analysis of B. tabaci populations from 55 field sites revealed the existence of 12 B and 43 Q biotypes across 18 provinces in China. The acquisition and transmission experiments showed that both B and Q biotypes can acquire and transmit the virus, however, Q biotype demonstrated superior acquisition and transmission capability than its B counterparts. Specifically, Q biotype acquired significantly more viral DNA than the B biotype, and reached the maximum viral load in a substantially shorter period of time. Although TYLCV was shown to be transmitted horizontally by both biotypes, Q biotype exhibited significantly higher viral transmission frequency than B biotype. Vertical transmission result, on the other hand, indicated that TYLCV DNA can be detected in eggs and nymphs, but not in pupae and adults of the first generation progeny. CONCLUSIONS/SIGNIFICANCE: These combined results suggested that the epidemiology of TYLCV was aided differentially by the two invasive whiteflies (B and Q biotypes) through horizontal but not vertical transmission of the virus. This is consistent with the concomitant eruption of TYLCV in tomato fields following the recent rapid invasion of Q biotype whitefly in China.

Ecologists have long speculated that species with wider environmental ranges would have broader ranges in phenotype; however, most tests of this hypothesis have involved small numbers of species and/or closely related taxa. We related phenotypic variation in twelve salt marsh plant species from six families to variation in four environmental variables using multiple regression. Within species, plant phenotype was predictably related to environmental variation. Salinity was the most common predictor of plant traits, followed by organic content, water content and elevation. Across species, regressions of single plant trait CVs on range (2 × SD) of single environmental variables were not significant and did not support the hypothesis that species occupying broad environmental ranges would have broad ranges in phenotypes. However, regression of a composite phenotypic PCA1 on a composite environmental PCA1 showed a marginally significant (P = 0.054). linear relationship for 10 species. Considering the different patterns of response across species, the lack of a relationship between variation in single phenotypic traits and single environmental variables is likely because the distantly-related taxa employed fundamentally different morphological and physiological strategies to respond to environmental stress gradients. The significant relationship between composite environmental and phenotypic variables reflects the complex nature of species phenotypic response to multivariate environmental gradients. Specifically, in this system, species increase variation in the number of leaves, but decrease variation in leaf size in response to an increase in range of salinity and decrease in range of water and organic content.]]>

Many introduced plant species rely on mutualisms in their new habitats to overcome barriers to establishment and to become naturalized and, in some cases, invasive. Mutualisms involving animal-mediated pollination and seed dispersal, and symbioses between plant roots and microbiota often facilitate invasions. The spread of many alien plants, particularly woody ones, depends on pollinator mutualisms. Most alien plants are well served by generalist pollinators (insects and birds), and pollinator limitation does not appear to be a major barrier for the spread of introduced plants (special conditions relating to Ficus and orchids are described). Seeds of many of the most notorious plant invaders are dispersed by animals, mainly birds and mammals. Our review supports the view that tightly coevolved, plant-vertebrate seed dispersal systems are extremely rare. Vertebrate-dispersed plants are generally not limited reproductively by the lack of dispersers. Most mycorrhizal plants form associations with arbuscular mycorrhizal fungi which, because of their low specificity, do not seem to play a major role in facilitating or hindering plant invasions (except possibly on remote islands such as the Galapagos which are poor in arbuscular mycorrhizal fungi). The lack of symbionts has, however, been a major barrier for many ectomycorrhizal plants, notably for Pinus spp. in parts of the southern hemisphere. The roles of nitrogen-fixing associations between legumes and rhizobia and between actinorhizal plants and Frankia spp. in promoting or hindering invasions have been virtually ignored in the invasions literature. Symbionts required to induce nitrogen fixation in many plants are extremely widespread, but intentional introductions of symbionts have altered the invasibility of many, if not most, systems. Some of the world's worst invasive alien species only invaded after the introduction of symbionts. Mutualisms in the new environment sometimes re-unite the same species that form partnerships in the native range of the plant. Very often, however, different species are involved, emphasizing the diffuse nature of many (most) mutualisms. Mutualisms in new habitats usually duplicate functions or strategies that exist in the natural range of the plant. Occasionally, mutualisms forge totally novel combinations, with profound implications for the behaviour of the introduced plant in the new environment (examples are seed dispersal mutualisms involving wind-dispersed pines and cockatoos in Australia; and mycorrhizal associations involving plant roots and fungi). Many ecosystems are becoming more susceptible to invasion by introduced plants because: (a) they contain an increasing array of potential mutualistic partners (e.g. generalist frugivores and pollinators, mycorrhizal fungi with wide host ranges, rhizobia strains with infectivity across genera); and (b) conditions conductive for the establishment of various alien/alien synergisms are becoming more abundant. Incorporating perspectives on mutualisms in screening protocols will improve (but not perfect) our ability to predict whether a given plant species could invade a particular habitat.

Eupatorium adenophorum Spreng (Crofton weed) from Burma and Vietnam into Southern China since the 1940s. Currently, E. adenophorum’s main colonisation area is located in the Yunnan–Guizhou Plateau of China, where it has caused prominent economic and ecological problems. Sixty-three years ago, Crofton weed appeared in Menghai county, Yunnan Province, from where it dispersed northwards and eastwards at an average speed of 20 km year−1. The invasion of E. adenophorum nonetheless showed pronounced variations in both time and space. Spread was relatively slow in the initial invasion period between 1940 and 1950, while the most rapid range expansions occurred in the 1980s. Environmental conditions at native and invaded sites were significantly different, reflecting a great adaptability of the species during colonization. These changes were greater than habitat differences between colonized and many adjacent un-colonized sites in Southern China. Therefore, immediate measures are required to stop a further northward and eastward expansion of Crofton weed.]]>

Phytotoxicity-directed extraction and fractionation of the aerial parts of Mikania micrantha H.B.K. led to the isolation and identification of three sesquiterpenoids: dihydromikanolide, deoxymikanolide, and 2,3-epoxy-1-hydroxy-4,9-germacradiene-12,8:15,6-diolide. These sesquiterpenoids inhibited both germination and seedling growth of tested species with deoxymikanolide possessing the strongest phytotoxicity. In a bioassay against lettuce (Lectuca sativa L.), deoxymikanolide reduced radicle elongation at low concentration (IC50 = 47 microg/ml); dihydromikanolide showed a weaker effect (IC50 = 96 microg/ml), and 2,3-epoxy-1-hydroxy-4,9-germacradiene-12,8:15,6-diolide exhibited the least effect (IC50 = 242 microg/ml). Deoxymikanolide caused yellowish lesions at the root tips of lettuce at a concentration of 50 microg/ml, and a 250 microg/ml solution killed lettuce seedlings. A bioassay against the monocot ryegrass (Lolium multiforum) revealed similar results on radicle elongation, which implied that the growth inhibition by these compounds was not selective. To evaluate their phytotoxicity to plants in natural habitats, three common companion tree species in south China, Acacia mangium, Eucalyptus robusta, and Pinus massoniana, were also tested and similar results were obtained. This is the first report on the isolation of 2,3-epoxy-1-hydroxy-4,9-germacradiene-12,8:15,6-diolide as a naturally occurring product.

The rice water weevil (RWW) Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae) is an invasive insect pest of rice Oryza sativa L. in China. Little is known about the interactions of this weevil with indigenous herbivores. In the present study, adult feeding and population density of the weevil, injury level of striped stem borer Chilo suppressalis (Walker) (Lepidoptera: Pyralidae) and pink stem borer Sesamia inferens (Walker) (Lepidoptera: Noctuidae) to rice, as well as growth status of their host plants were surveyed in a rice field located in Southeastern Zhejiang, China, in 2004 with the objective to discover interspecific interactions on the rice. At tillering stage, both adult feeding of the weevil and injury of the stem borers tended to occur on larger tillers (bearing 5 leaves) compared with small tillers (bearing 2~4 leaves), but the insects showed no evident competition with each other. At booting stage, the stem borers caused more withering/dead hearts and the weevil reached a higher density on the plants which had more productive tillers and larger root system; the number of weevils per tiller correlated negatively with the percentage of withering/dead hearts of plants in a hill. These observations indicate that interspecific interactions exist between the rice water weevil and the rice stem borers with negative relations occurring at booting or earlier developmental stages of rice.

Bemisia tabaci (Gennadius) biotype B, called a