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Anoplophora glabripennis (Asian longhorned beetle) is a wood-boring pest that can inhabit a wide range of healthy deciduous host trees in native and non-native habitats. Lignocellulose degradation plays a major role in the acquisition of nutrients during the growth and development of A. glabripennis larvae. In this study, the lignocellulose degradation capacity of Fusarium solani, a fungal symbiont of A. glabripennis, was investigated in fermentation culture and in four host tree species. The impact of F. solani on larval growth and survival parameters was assessed. Fermentation culture demonstrated continuous and stable production of lignocellulolytic enzymes over the cultivation period. Furthermore, F. solani was able to degrade host tree lignocellulose, as shown by decreased soluble sugar and cellulose contents and an increase in protein content. No significant differences in larval survival were observed in larvae fed with or without F. solani. However, weight and head capsule width were higher in larvae fed on F. solani, and gut lignocellulose activities were elevated in fed larvae. Our results indicate a role for F. solani in the predigestion of lignocellulose during the colonization and parasitic stages of A. glabripennis larval development, and also the F. solani an important symbiotic partner to A. glabripennis, lowering barriers to colonization and development in a range of habitats. [ABSTRACT FROM AUTHOR]

Background: Pine wilt disease (PWD) is a major ecological concern in China that has caused severe damage to millions of Chinese pines (Pinus tabulaeformis). To control the spread of PWD, it is necessary to develop an effective approach to detect its presence in the early stage of infection. One potential solution is the use of Unmanned Airborne Vehicle (UAV) based hyperspectral images (HIs). UAV-based HIs have high spatial and spectral resolution and can gather data rapidly, potentially enabling the effective monitoring of large forests. Despite this, few studies examine the feasibility of HI data use in assessing the stage and severity of PWD infection in Chinese pine. Method: To fill this gap, we used a Random Forest (RF) algorithm to estimate the stage of PWD infection of trees sampled using UAV-based HI data and ground-based data (data directly collected from trees in the field). We compared relative accuracy of each of these data collection methods. We built our RF model using vegetation indices (VIs), red edge parameters (REPs), moisture indices (MIs), and their combination. Results: We report several key results. For ground data, the model that combined all parameters (OA: 80.17%, Kappa: 0.73) performed better than VIs (OA: 75.21%, Kappa: 0.66), REPs (OA: 79.34%, Kappa: 0.67), and MIs (OA: 74.38%, Kappa: 0.65) in predicting the PWD stage of individual pine tree infection. REPs had the highest accuracy (OA: 80.33%, Kappa: 0.58) in distinguishing trees at the early stage of PWD from healthy trees. UAV-based HI data yielded similar results: the model combined VIs, REPs and MIs (OA: 74.38%, Kappa: 0.66) exhibited the highest accuracy in estimating the PWD stage of sampled trees, and REPs performed best in distinguishing healthy trees from trees at early stage of PWD (OA: 71.67%, Kappa: 0.40). Conclusion: Overall, our results confirm the validity of using HI data to identify pine trees infected with PWD in its early stage, although its accuracy must be improved before widespread use is practical. We also show UAV-based data PWD classifications are less accurate but comparable to those of ground-based data. We believe that these results can be used to improve preventative measures in the control of PWD. [ABSTRACT FROM AUTHOR]

Background: Anoplophora glabripennis (Motschulsky), commonly known as Asian longhorned beetle (ALB), is a wood-boring insect that can cause lethal infestation to multiple borer leaf trees. In Gansu Province, northwest China, ALB has caused a large number of deaths of a local tree species Populus gansuensis. The damaged area belongs to Gobi desert where every single tree is artificially planted and is extremely difficult to cultivate. Therefore, the monitoring of the ALB infestation at the individual tree level in the landscape is necessary. Moreover, the determination of an abnormal phenotype that can be obtained directly from remote-sensing images to predict the damage degree can greatly reduce the cost of field investigation and management. Methods: Multispectral WorldView-2 (WV-2) images and 5 tree physiological factors were collected as experimental materials. One-way ANOVA of the tree's physiological factors helped in determining the phenotype to predict damage degrees. The original bands of WV-2 and derived vegetation indices were used as reference data to construct the dataset of a prediction model. Variance inflation factor and stepwise regression analyses were used to eliminate collinearity and redundancy. Finally, three machine learning algorithms, i.e., Random Forest (RF), Support Vector Machine (SVM), Classification And Regression Tree (CART), were applied and compared to find the best classifier for predicting the damage stage of individual P. gansuensis. Results: The confusion matrix of RF achieved the highest overall classification accuracy (86.2%) and the highest Kappa index value (0.804), indicating the potential of using WV-2 imaging to accurately detect damage stages of individual trees. In addition, the canopy color was found to be positively correlated with P. gansuensis' damage stages. Conclusions: A novel method was developed by combining WV-2 and tree physiological index for semi-automatic classification of three damage stages of P. gansuensis infested with ALB. The canopy color was determined as an abnormal phenotype that could be directly assessed using remote-sensing images at the tree level to predict the damage degree. These tools are highly applicable for driving quick and effective measures to reduce damage to pure poplar forests in Gansu Province, China. [ABSTRACT FROM AUTHOR]

Masson pine stands infected by Pine wilt disease (PWD) in the Three Gorges Reservoir Region of central China were surveyed to quantify the immediate responses and subsequent trajectories of biomass, carbon (C), and nitrogen (N) in stand-level major ecosystem compartments. The biomasses of above- and belowground tree components, as well as of the understory, forest floor, and mineral soil (0–40 cm), were determined within each stand. C and N storage were also estimated for each ecosystem compartment. Overstory biomass decreased steadily with the extent of PWD infection. Understory biomass ranged from 1.97 to 4.16 Mg ha−1, and the observed value for forest floor biomass was 12.89–22.59 Mg ha−1. The highest mean C and N concentrations were found in the stem bark and needles of Masson pine, respectively, while the lowest were found in the semi- to fully decomposed layer of the forest floor and stem wood of Masson pine, respectively. The C and N storage of aboveground trees, tree roots, and the aboveground ecosystem decreased with the extent of PWD infection. However, the C and N contents of the understory, forest floor, and total mineral soil initially declined after PWD infection before recovering over the following several years. Those result concluded that the biomass, C, and N storage of different forest ecosystem compartments have experienced certain variations following the PWD epidemic. This is vital to understand the shifts in stand-level C and N allocation in PWD-damaged forest stands, as well as for predicting the responses of regional and global C and N cycling. [ABSTRACT FROM AUTHOR]

The gypsy moth Lymantria dispar (Linnaeus) is a highly polyphagous herbivore that defoliates a wide variety of tree species. The influence of age and mating status on the flight activity of females was assessed in seven geographically isolated populations from China. We examined flight activity of tethered females using a computer-linked flight mill in the laboratory and found that age significantly influenced flight parameters, including total flight distance, time, and speed. Flight distance peaked in the youngest females (at 1 day of age) and declined with age. No significant differences in flight parameters were found between unmated and mated females. Females from Guizhou showed the strongest flight activity among all seven populations. The total flight distances, flight times, and maximum flight speeds at 1 day of age were 7.50 ± 2.28 km, 2.17 ± 0.51 h, and 6.18 ± 0.51 km/h, respectively. These results provide valuable information regarding the scale and speed of dispersal in hotspots and can improve the management and control of forest damage. [ABSTRACT FROM AUTHOR]

Arceuthobium sichuanense is an aerial parasitic plant (dwarf mistletoe) which causes severe damage to spruce forests on the Qinghai-Tibet Plateau. Picea crassifolia and Picea purpurea, two main host species of A. sichuanense, have different growth characteristics and elevational distributions. The effects of A. sichuanense infection on P. crassifolia and P. purpurea trees were evaluated by examining needle and current-year shoot morphology, needle water use efficiency and needle nitrogen concentration, with 30 needle samples, 30 current-year shoot samples and 10 A. sichuanense aerial shoot samples for each host species. The most apparent effects were significant reductions in both needle size and current-year shoot length. The high degree of correlation in foliar δ N values between the dwarf mistletoe and its host trees indicated that nitrogen in the dwarf mistletoe was derived entirely from its host. Percent reductions in needle and current-year shoot length were smaller for P. purpurea than for P. crassifolia, possibly suggesting that P. purpurea exhibits a lesser capacity to accommodate the parasitic effects of mistletoe infection by adjusting the growth of needles and current-year shoots. The reductions in needle nitrogen concentration and δ C values were lower in P. purpurea than in P. crassifolia, indicating that P. purpurea suffered more nitrogen and water stresses and exhibited lower vigor compared to P. crassifolia. Our results demonstrated that P. purpurea may suffer more negative effects induced by dwarf mistletoe infections at needle and branch levels than P. crassifolia. [ABSTRACT FROM AUTHOR]

Background: The red palm weevil, Rhynchophorus ferrugineus, is a lethal pest of the palms. The identification of odorant binding protein (OBP) genes will be helpful for clarifing the mechanism of odorant detection of this pest. By sequencing the full length cDNA library of its antenne, 11 OBP genes (RferOBP1-11) were identified. Findings: The result showed RferOBP1-7 and RferOBP8-11 belonged to the minus-C and classic family, respectively qPCR revealed that RferOBP1-10 highly transcribed in the antennae, of which RferOBP1, RferOBP4, RferOBP8 and RferOBP10 were obviously male-biased expression. RferOBP7 and RferOBP11 exhibited highly expression in female head and male thorax. RferOBP2, RferOBP5 and RferOBP6 were highly expressed in the female thorax, leg and abdomen respectively. Conclusions: The results paved the way towards a future understanding of the olfaction in this species. [ABSTRACT FROM AUTHOR]

This paper summarizes the results of our study of the pinewood nematode ( Bursaphelenchus xylophilus). By population genetic analysis, it was determined that there was no genetic bottle caused by the founder effect and genetic drift in the Chinese invasive population. Multiple invasions with large amounts of nematodes from different sources led to rich genetic diversity in the invasive population. Keeping high genetic diversity in the invasive process may be one of the genetic mechanisms in its successful invasion. By testing interspecies competition, it was shown that, with high fecundity and a strong competitive ability, B. xylophilus outcompeted the native species B. mucronatus in the natural ecosystem during the invasion process. Competitive displacement may be one of the ecological mechanisms of B. xylophilus’s invasion. In addition, an unequal interspecific hybridization with introgress was in favor of the invasive species which also accelerated the replacement of B. mucronatus by B. xylophilus. The structures, functions and evolutions of a few important genes that are closely related to the ecological adaptation of pinewood nematodes were studied to explore the molecular mechanism of its ecological adaptations. Further, the resistance and resilience mechanism of the pine ecosystem invaded by pinewood nematodes was also investigated. The results of these studies uncovered a portion of the genetic and ecological mechanisms of PWN’s successful invasion and laid a foundation for further study to obtain a comprehensive interpretation of the mechanisms of the nematode invasion. The results also provided a scientific basis for effectively controlling the occurrence and spread of pine wilt disease which is caused by nematodes. Various aspects requiring further investigation are considered. [ABSTRACT FROM AUTHOR]

Pine wood nematode (PWN, Bursaphelenchus xylophilus), originating from North America, causes destructive pine wilt disease. Different pine forest ecosystems have different resistances to B. xylophilus, and after its invasion, the resilience and restoration direction of different ecosystems also varies. In this study, an interpretative structural model was applied for analyzing the response of pine forest ecosystem to PWN disturbance. The result showed that a five-degree multi-stage hierarchical system affected the response of the pine forest ecosystem to PWN disturbance, in which direct affecting factors are resistance and resilience. Furthermore, the analysis to the 2nd, 3rd and 4th degree factors showed that not only does distribution pattern of plant species and pine’s ecological features affect the resistance of pine forests’ ecosystem, but removal of attacked trees and other measures also influence the resistance through indirectly affecting the damage degree of Monochamus alternatus and distribution pattern of plant species. As for resilience, it is influenced directly by soil factors, hydrology, surrounding species provenance and biological characteristics of the second and jointly dominant species, and the climate factors can also have a direct or indirect effect on it by affecting the above factors. Among the fifth elements, the elevation, gradient and slope direction, topographical factors, diversity of geographical location and improvement of prevention technology all influence the response of pine forest ecosystem to PWN disturbance. [ABSTRACT FROM AUTHOR]

To better understand the distribution of soil microorganisms in Populus euphratica forests in Xinjiang, northwestern China, we studied and compared the populations and numbers of bacteria, fungi and actinomycetes in the soil at four different age stages of natural P. euphratica forests, i.e., juvenile forests, middle-aged forests, over-mature forests and degraded forests. Results showed that there were clear differences in the amount of microorganism biomass and composition rates across the four forest stages. Dominant and special microorganisms were present in each of the four different soil layers. The vertical distribution showed that the microorganism biomass decreased with increasing soil depth. The population of microorganisms was the lowest at 31–40 cm of soil depth. The microorganisms consisted of bacteria, actinomycetes, as well as fungi. Bacteria were the chief component of microorganisms and were widely distributed, but fungi were scarce in some soil layers. Aspergillus was the dominant genus among the 11 genera of fungi isolated from the soil in different age stages of P. euphratica forests. [ABSTRACT FROM AUTHOR]

Reported in this paper are our findings of the study on changes in species diversity of different Masson pine communities after the invasion of Bursaphelenchus xylophilus (Steiner and Buhren) Nickle and subsequent and different removal disturbance management approaches. Based on the results, the species diversity indices for the arbor layers of the different communities can be arranged in the following order (from high to low): 1) broad-leaved stand after the removal of all infected pine trees in the pure pine stand in Fuyang; 2) lightly infected Masson pine and Schima superba mixed stand in Fuyang; 3) uninfected stand mixture of Masson pine and Castanopsis fargesii as a control; 4) lightly infested pure Masson pine stand in Fuyang; 5) Quercus variables stand formed following the selective removal of infected pine trees from a mixed Masson pine and Q. variables stand in Zhoushan Islands; 6) pure young Masson pine stand formed following the removal of all infected pine trees from a pure Masson pine stand; 7) pure Liquidambar formosana stand after the removal of infected pine trees from a pure pine stand in Zhoushan Islands; 8) a mixed stand consisting of Pinus thunbergii and the Masson pine in Zhoushan Island; and 9) moderately infected Masson pine stand in Zhoushan Islands. All the three diversity indices ( R 0 = richness, H′ = Shannon-Wiener index, and E = evenness) for the shrub layer did not show any significant differences among the various communities except for the pure pine stand in Zhoushan Island, which had the lowest diversity. The three indices for the herb layer of the pure young Masson pine, Q. variables stand, and L. formosana stand were higher than that of other stands. The integrated analysis showed that the Masson pine forest in different geographical situations and extent of damage had distinct disparity, just as in different disturbance degrees and restoring manners. We created the “index of disturbing intensity of stump and fallen woods” (IDISFW) to represent the degree of disturbance of tree removal to plant diversity. We found that the relationship between the species diversity index and the IDISFW shows both a lower and higher degree of removal disturbance that follows the “mid-altitude bulge” theory. Specifically, both excessive and insufficient removal of infected trees will cause a decline of plant species diversity to a certain degree. Covariance analysis indicated that different IDISFW had no significant effects on the species diversity of the arbor layer, but had different impacts on that of the shrub and herb layers, and therefore can be used to assess changes in species diversity of different Masson pine communities after the invasion of pine wood nematode. [ABSTRACT FROM AUTHOR]

In November 2003 and June 2004, the insect borers and their spatial distribution within Pinus massoniana were investigated in Zhoushan City, in East China’s Zhejiang Province, where pine wood nematode ( Bursaphelenchus xylophilus) are typically found. The niche width, proportional similarity of niche and the niche overlap of dominant species of dying trees were computed. Results show that five insect species infect and damage Pinus massoniana, which had been infected by pine wood nematodes, among which four are wood boring beetles and one termite. Species within host trees vary from winter to summer and all the species have their own niche width, proportional similarity of niche and the niche overlap. They can achieve competitive equilibrium and coexistence according to their biological characteristics and life habits. [ABSTRACT FROM AUTHOR]

According to the international methods of pest risk analysis and urban forestry characteristics in Beijing, a quantitative risk assessment system in Beijing for three primary non-indigenous pests was proposed. This system was used to analyze three major non-indigenous species, Dendroctonus valens, Hyphantria cunea, and Apriona swainsoni. The results show that the risks of these three pests in the Beijing area were 2.46, 2.30, and 2.02, which were all highly risky. Based on the result and extensive risk communications, combined with the management experience of the Beijing Forest Protection Station, the authors proposed some effective control measures to prevent the invasion of the three pests into Beijing. [ABSTRACT FROM AUTHOR]

In order to understand the occurrence and the developmental regularity of seabuckthorn carpenterworm ( Holcocerus hippophaecolus) and predict its population density, the developmental threshold temperature ( C) and effective accumulative temperature ( K) of the carpenterworm pupae and eggs were analyzed under the conditions of constant and variable temperatures. The results show that the values of C and K of the carpenterworm pupae are (12.1±0.2) °C and (295.2±4.1) day-degrees at constant temperatures, and (15.5±0.4) °C and (202.4±13.1) day-degrees at variable temperatures. However, the values of C and K of the eggs at variable temperatures are (16.7±0.8) °C and (101.5±12.6) day-degrees. The differences of developmental threshold and effective accumulative temperature under the conditions of constant and variable temperatures of the carpenterworm pupae accord with the developmental regularity of most insects in nature. By comparing five different constant temperatures, the conclusion is that the optimum developmental temperature of the pupae is 21 °C when both the pupation of the mature larvae and the eclosion of the pupae are very accordant. Moreover, the percentage of eclosion is over 90%. The average developmental durations of the carpenterworm pupae and eggs are 31 and 16 d at variable temperatures. [ABSTRACT FROM AUTHOR]