Hide and seek in forests: colonization by the pine processionary moth is impeded by the presence of nonhost trees

• 1 The disruption of host‐finding cues has been proposed as a key mechanism underlying the lower damage caused by phytophagous insects in mixed forests. We tested this hypothesis by investigating the distribution of pine processionary moth Thaumetopoea pityocampa (Denis & Schiffer‐Müller) (Lepidoptera) infestation at the edges of pure stands of Pinus pinaster (AÏton) at some distance from nonhost trees (Experiment 1) or bordered in part by a broadleaved hedgerow (Experiment 2).
• 2 An ‘edge effect' was demonstrated, with trees at the edge of the stand being more heavily infested than those at the interior of the stand.
• 3 The presence of a nonhost broadleaved hedgerow in front of the edge of the pine stand resulted in lower T. pityocampa infestation. There were significantly fewer T. pityocampa nests behind the hedgerow than on the exposed part of the edge. The presence of the hedgerow did not dilute or repel T. pityocampa infestation further into the pine stand, although it decreased the infestation of T. pityocampa throughout the pine stand. The decrease in T. pityocampa infestation behind the hedgerow was greater when the broadleaved hedgerow was taller than the pine trees.
• 4 These results highlight the benefits of using nonhost tree species on the edge of monospecific forest stands to reduce insect damage. This approach could be promoted as an innovative forest pest management method.

     

Evaluation of sampling methods and development of sample plans for estimating predator densities in cotton

The cost-reliability of five sampling methods (visual search, drop cloth, beat bucket, shake bucket, and sweep net) was determined for four groups of predatory arthropods on cotton plants in Texas. The beat bucket sample method was the most cost-reliable sampling method for Orius adults, and the beat bucket and drop cloth were the most cost-reliable methods for Orius nymphs. The drop cloth and beat bucket were the most cost-reliable methods for sampling spiders. For sampling adult Coccinellidae, the sweep net and the beat bucket were the most cost-reliable. The visual sample method was the least cost-reliable method for Orius adults and nymphs and spiders. No one sampling method was identified as the optimum method for all four predator groups. However, the relative cost-reliability of the beat bucket method ranked first or second among the five sampling methods and this method was chosen for further evaluation in field studies in Texas and Arizona. The relative cost-reliability of 1-, 3-, 5-, and 10-plants per beat bucket sample varied with predator group, but multiple plant sample units were equal to or more cost-reliable than the one plant sample unit. Fixed sample plans for the beat bucket method were developed for Orius adults, Orius nymphs, spiders, and adult Coccinellidae, and the sum of these groups using the 3-, 5-, and 10-plant sample unit sizes. The greater cost-reliability of the beat bucket sampling method and its ease of use is of particular advantage in assessing predator densities in a commercial cotton field monitoring program.     

Biological invasions provide a framework for reintroductions: selecting areas in England for pine marten releases

We suggest that reintroductions, like biological invasions, have two phases: establishment when a new population becomes self-sustaining, and spread when a population increases its distribution. Stochastic effects on mortality and sex ratios are most likely to determine whether a population becomes established, while factors influencing birth rates will probably most influence spread. Using this establishment-spread structure, we evaluate the autecological suitability of regions in England for pine marten Martes martes reintroductions. Risks of mortality from predator control, traffic accidents and predation by foxes were used to evaluate suitability for establishment. Mortality risk was higher in all potential release regions in England (selected as having 25% or more woodland cover) than in regions of current pine marten distribution in Scotland; risk of predation was higher in the latter. Indices of prey abundance were used to evaluate suitability for populations to spread. Prey indices in potential release regions were generally higher than in regions of current distribution. A relation between prey, woodland cover, and known pine marten densities suggested that potential release regions are capable of supporting relatively high densities of pine martens, though these might be reduced by higher mortality. We concluded that all potential release regions are suitable for pine marten populations to spread. However, reintroductions should first be to regions with lower risk of mortality, in case higher levels of the latter prevent establishment. The suitability of relict regions of distribution in northern England was low until post-war afforestation, suggesting that habitat suitability constrained recovery of relict populations. These regions remain less suitable for reintroductions.     

Empirical parameters for estimating protein-protein binding energies: number of short- and long-distance atom-atom contacts

The number of atom-atom contacts in long distance can fit to the experimental binding energies in a dataset containing 151 experimental data with the correlation coefficient about 0.68. Based on this factor, a set of distance-dependent empirical potentials for various types of short-distance (2.4 A-5 A) contacts was obtained by guided fitting, i.e. a set of two parameters fitting. Incorporation of these short-distance potentials improved the correlation coefficients to 0.881.     

Temperature-absorption transition spectroscopy: a technique for estimating the relative charge densities on thiolated phosphate groups in nucleic acid analogues

Various polynucleotides with well-defined sequences at low salt concentration have been studied using temperature-absorbtion transition spectroscopy to understand their conformations. It has been observed that the adopted technique can fairly estimate the relative charge densities at the thiolated phosphate groups in nucleic acid analogues at low salt concentrations.     

Within-plant distribution of soybean aphid (Hemiptera: Aphididae) and development of node-based sample units for estimating whole-plant densities in soybean

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is capable of reducing soybean, Glycine max (L.) Merr., yield up to 40% during severe outbreaks. Frequent sampling, which can be costly and time-consuming, is essential to making informed management decisions. However, one way to decrease sampling effort is to use a reduced sample unit when possible. The objectives of this study were to describe the vertical distribution of soybean aphid within soybean over time and to define node-based sample units of varying sizes by testing the ability of selected units to accurately estimate whole-plant aphid density. Within-plant distribution of soybean aphid changed significantly with time. However, the average nodal position where soybean aphids were found on soybean remained within the top half of the plant at all three locations studied across all sample dates. Consequently, selecting the node with the highest aphid density multiplied by the total number of infested nodes (N(MAX)') was the best predictor of aphids on remaining soybean components in both the original (r2 = 0.855) and validation (r2 = 0.824) data sets. For sample units that included more than a single node to estimate densities, a weighted formula, which incorporated changes observed in the within-plant aphid distribution, improved model performance (higher r2 values) and reduced variability around parameter estimates compared with a node-averaged formula. Our results suggest that smaller sample units provide reliable estimations of whole-plant aphid density throughout the growing season for differently maturing soybean, which is essential to their use in pest management decisions and development of future sampling plans.     

Regressions for estimating muscle parameters in the thoracic and lumbar trunk for use in musculoskeletal modeling

Musculoskeletal modeling requires information on muscle parameters such as cross-sectional area (CSA) and moment arms. A variety of previous studies have reported muscle parameters in the trunk based on in vivo imaging, but there remain gaps in the available data as well as limitations in the generalizability of such data. Specifically, available trunk muscle CSA data is very limited for older adults, lacking entirely in the thoracic region. In addition, previous studies have made measurements in groups of healthy volunteers or hospital patients who may not be representative of the population in general. Finally, such studies have not reported data for the major muscles connecting the upper limb to the thoracic trunk. In this study, muscle morphology measurements were made for major muscles present in the trunk between vertebral levels T6 and L5 using quantitative computed tomography scans from a community-based sample of 100 men and women aged 36-87. We present regression equations to predict trunk muscle CSA and position relative to the vertebral body in the transverse plane from sex, age, height and weight at vertebral levels T6 to L5. Regressions were also developed for predicting anatomical CSA and muscle moment arms, which were estimated using literature data on muscle line of action. This work thus provides a resource for estimating muscle parameters in the general population for musculoskeletal modeling of the thoraco-lumbar trunk.     

The line transect method for estimating densities of large mammals in a tropical deciduous forest: An evaluation of models and field experiments

We have evaluated techniques of estimating animal density through direct counts using line transects during 1988–92 in the tropical deciduous forests of Mudumalui Sanctuary in southern India for four species of large herbivorous mammals, namely, chital (Axis axis). sambar (Cervus unicolor). Asian elephant (Elephas maximus) and gaur (Bos gaurus) Density estimates derived from the Fourier Series and the Half-Normal models consistently had the lowest coefficient of variation. These two models also generated similar mean density estimates. For the Fourier Series estimator, appropriate cut-off widths for analyzing line transect data for the four species are suggested. Grouping data into various distance classes did not produce any appreciable differences in estimates of mean density or their variances, although model fit is generally better when data arc placed in fewer groups. The sampling effort needed to achieve a desired precision (coefficient of variation) in the density estimate is derived. A sampling effort of 800 km of transects returned a 10% coefficient of variation on estimate for ehital; for the other species a higher effort was needed to achieve this level of precision. There was no statistically significant relationship between detectability of a group and the size of the group for any species. Density estimates along roads were generally significantly different from those in the interior of the forest, indicating that road-side counts many not be appropriate for most species.     

2D与3D景观指数测定山区植被景观格局变化对比分析

植被和土地覆盖变化是环境变化的一个重要因素,同时也是引起景观和生态系统变化的重要原因。景观指数是定量分析植被和土地覆盖变化的重要研究方法之一。以滇西北高山峡谷区为案例区,比较分析传统2D景观指数和3D景观指数进行植被变化定量测定的差异。研究主要选取了基于斑块面积和周长几个常用指数来进行比较分析。研究结果表明在斑块层次上,除了分维数指数,其他指数的三维方法计算值显著地高于二维方法计算值;在类型层次上,三维的类型面积指数、平均斑块面积指数、平均最小邻近距离指数测定的变化值显著大于二维的相应指数测定变化值,但是二维和三维平均形状指数和分维指数测定的植被斑块的平均形状变化结果没有显著差异;在景观层次,只有三维的平均斑块面积和最小邻近距离指数测定的变化结果显著高于二维的平均面积和最小邻近距离指数测定的变化结果,其它指数如形状指数、分维指数、多样性指数和均一度指数等测定出两个不同时期的植被图格局变化结果均无显著差异,主要由于这些指数是采用面积和周长的对数或者比值计算得出,从而缩小了斑块表面面积与平面面积,表面周长与平面周长之间的差异。总体而言,利用二维景观指数在进行定量分析山区植被格局变化时,往往低估了其类型面积、平均斑块面积、斑块邻近距离等指数变化量,而三维景观指数得到相对较精确的变化值。     

川西高原山地美味牛肝菌气候生态适宜性及潜在分布

利用数字高程模型(DEM)数据、土地覆盖栅格数据、四川省52个站点和4个其他省市站点的气象观测数据,基于美味牛肝菌的生物学特性,结合前人研究成果,系统分析了川西高原山地美味牛肝菌的气候生态适宜性。选取气温、降水、植被等影响因子作为区划指标,应用集优法,通过GIS分析本区美味牛肝菌资源的潜在分布。结果表明: 美味牛肝菌潜在分布区的北界在32° N附近,海拔上限约为3000 m,下限约为800 m,总面积约286.3万hm²,约占研究区整个行政区域面积的9.7%;29° N以南的攀西地区是美味牛肝菌的主要潜在分布区,核心分布区在攀西地区中南部,攀西分布区面积约占全部潜在分布区的90%,其中,适宜区面积约占20%,次适宜面积约占80%。适宜区主要分布于攀西地区雅砻江以东的安宁河流域、海拔1000~2600 m的山区;次适宜区主要是适宜区分别向上、向下延伸到海拔3000和800 m左右的林区;海拔3000 m以上的高原高山区和海拔800 m以下的干热河谷区为不适宜区。     

Identifying important conservation areas for the clouded leopard Neofelis nebulosa in a mountainous landscape: Inference from spatial modeling techniques

The survival of large carnivores is increasingly precarious due to extensive human development that causes the habitat loss and fragmentation. Habitat selection is influenced by anthropogenic as well as environmental factors, and understanding these relationships is important for conservation management. We assessed the environmental and anthropogenic variables that influence site use of clouded leopard Neofelis nebulosa in Bhutan, estimated their population density, and used the results to predict the species’ site use across Bhutan. We used a large camera‐trap dataset from the national tiger survey to estimate for clouded leopards, for the first time in Bhutan, (1) population density using spatially explicit capture–recapture models and (2) site‐use probability using occupancy models accounting for spatial autocorrelation. Population density was estimated at (0.10 SD) and (0.12 SE) per 100 km². Clouded leopard site use was positively associated with forest cover and distance to river while negatively associated with elevation. Mean site‐use probability (from the Bayesian spatial model) was (0.076 SD). When spatial autocorrelation was ignored, the probability of site use was overestimated, (0.066 SD). Predictive mapping allowed us to identify important conservation areas and priority habitats to sustain the future of these elusive, ambassador felids and associated guilds. Multiple sites in the south, many of them outside of protected areas, were identified as habitats suitable for this species, adding evidence to conservation planning for clouded leopards in continental South Asia.     

A novel approach for estimating growth phases and parameters of bacterial population in batch culture

Using mathematical analysis, a new method has been developed for studying the growth kinetics of bacterial populations in batch culture. First, sampling data were smoothed with the spline interpolation method. Second, the instantaneous rates were derived by numerical differential techniques and finally, the derived data were fitted with the Gaussian function to obtain growth parameters. We named this the Spline-Numerical-Gaussian or SNG method. This method yielded more accurate estimates of the growth rates of bacterial populations and new parameters. It was possible to divide the growth curve into four different but continuous phases based on changes in the instantaneous rates. The four phases are the accelerating growth phase, the constant growth phase, the decelerating growth phase and the declining phase. Total DNA content was measured by flow cytometry and varied depending on the growth phase. The SNG system provides a very powerful tool for describing the kinetics of bacterial population growth. The SNG method avoids the unrealistic assumptions generally used in the traditional growth equations.     

A novel approach for estimating growth phases and parameters of bacterial population in batch culture

Traditionally, microbiologists divided bacterial growth in batch cultures into lag, exponential, station-ary and death phases[1], following the Logistic equa-tion that has been applied to the growth of human populations. The growth curves can always be ch…     

New species from the Galoka and Kalabenono massifs: two unknown and severely threatened mountainous areas in NW Madagascar

The Galoka mountain chain, comprising principally the Galoka and Kalabenono massifs, situated at the northern edge of the Sambirano Region in NW Madagascar is an area that was virtually unknown botanically. It was visited three times between 2005 and 2007 as part of a floristic inventory. Both massifs contain the last remaining primary forests in the Galoka chain, which extends parallel to the coastline from South of Ambilobe to North of Ambanja. Several new species have been discovered amongst the collections, eight of which are described here.     

Evidence for large-scale effects of competition: niche displacement in Canada lynx and bobcat

Determining the patterns, causes and consequences of character displacement is central to our understanding of competition in ecological communities. However, the majority of competition research has occurred over small spatial extents or focused on fine-scale differences in morphology or behaviour. The effects of competition on broad-scale distribution and niche characteristics of species remain poorly understood but critically important. Using range-wide species distribution models, we evaluated whether Canada lynx (Lynx canadensis) or bobcat (Lynx rufus) were displaced in regions of sympatry. Consistent with our prediction, we found that lynx niches were less similar to those of bobcat in areas of sympatry versus allopatry, with a stronger reliance on snow cover driving lynx niche divergence in the sympatric zone. By contrast, bobcat increased niche breadth in zones of sympatry, and bobcat niches were equally similar to those of lynx in zones of sympatry and allopatry. These findings suggest that competitively disadvantaged species avoid competition at large scales by restricting their niche to highly suitable conditions, while superior competitors expand the diversity of environments used. Our results indicate that competition can manifest within climatic niche space across species’ ranges, highlighting the importance of biotic interactions occurring at large spatial scales on niche dynamics.     

Patterns of endemism and species richness in Malagasy cophyline frogs support a key role of mountainous areas for speciation

Cophyline narrow-mouthed frogs (Anura: Microhylidae) are a diverse endemic radiation of Madagascar. Cophylines contain a high proportion of range restricted species and constitute a good model system to understand patterns of evolutionary diversification in tropical ecosystems. We combine spatial and phylogenetic analyses for a near-complete taxon sample to test competing explanations for patterns of species richness (SR) and endemism. Our reconstruction of the phylogeny of cophylines indicates the presence of 22 new species and several instances of nonmonophyly. We found a strong historical signal in current cophyline ranges indicating a high degree of spatial niche conservatism in clade diversification, with clades occurring in the North of Madagascar constituting the most derived in the phylogeny. We identified six positively correlated centers of SR and endemism that can neither be explained by stochastic models such as elevational or latitudinal mid-domain effect, nor by low-elevation river catchments. Instead, the locations of these centers in areas spanning a high altitudinal range in combination with specific climatic parameters support a key role of mountainous areas for speciation of these anurans, although we cannot exclude an influence of habitat loss due to human impact. High conservation priority is ascribed to these areas.