From biology to management of Savi's pine vole (Microtus savii)

Savi's pine vole (Microtus savii) is a rodent species of the Cricetidae family, inhabiting southern European agroecosystems. It is considered to be the main cause of rodent‐attributed damage in Italy. To achieve an effective management, detailed knowledge of this species is needed. However, the available information about this species is fragmentary and incomplete. In this paper, the existing knowledge of Savi's pine vole taxonomy, reproduction, population dynamics, habitat and food preferences is reviewed in order to organise available information and identify priority areas of future research. Some of the changes in farming practices that have occurred in recent decades may have increased the impact of Savi's pine vole populations in crop fields. To manage this pest species effectively, an integrated strategy is recommended (involving habitat management, trapping and, when appropriate, the use of rodenticides). The apparent lack of cyclical population outbreaks and the relatively small litter size and long gestation and interpartum period of this species suggest that it could be more manageable than other vole species, while its strict herbivorous diet, stable population size in open habitats and wide distribution seem to indicate it as an ideal model species for risk assessment studies. © 2015 Society of Chemical Industry     

栗钙土农田土壤养分空间变异特性及采样方法研究

以西宁市二十里铺村的农田为研究区域,采用5 m×5 m网格法,选取84个观测点取样,进行室内分析,测定土壤有机质、水解氮、速效磷、速效钾的含量,分析土壤养分的空间变异规律。研究表明,土壤有机质、水解氮、速效钾的空间变异性不太明显,速效磷的空间变异性明显;有机质、水解氮和速效钾的空间变异主要是由结构性因素引起的,速效磷的空间变异是由随机因素引起的。有机质的变异函数理论模型为指数模型,水解氮、速效磷、速效钾变异函数理论模型为球形模型。栗钙土农田采样的密度范围在1~11 m之间,将能够满足精确农业生产对这4种土壤养分的分析要求。     

新疆盐渍化区土壤养分的空间结构和分布特征

结合地理信息系统(GIS),在面积约为2000km2的新疆典型盐渍化区渭干河流域布设了土壤取样点43个,测定了土壤表层(0~30cm)养分(全氮、全磷、全钾、碱解氮、速效磷、速效钾)的空间变异规律。结果表明:七种养分元素中除了碱解氮、速效磷的含量服从对数正态分布,其它养分元素均符合正态分布;半方差分析得出各项目都能很好的用模型来拟合,全氮、全磷、速效钾符合指数模型,碱解氮、速效磷、全磷符合球状模型。只有有机质是符合高斯模型;全氮和碱解氮的系统空间相关性很弱,而其余养分元素均表现出中等强度的空间相关性,变程在14.3km~67.0km之间,相差比较大;用Kriging插值法对未测点的养分元素进行最优估计,绘制含量分布图,从而可以更直观的反映研究区土壤养分的空间结构和分布特征。     

Providing management options to control corn mouse (Calomys musculinus) reservoir populations using a cohort structured model

We evaluate several management options for Calomys musculinus populations through the formulation and validation of a cohort structured model. Initially, a basic model was constructed and validated using field population data. Next, the model was altered to allow us to evaluate different management options. In general, basic model results were in agreement with field data, demonstrating that this model would be useful in describing aspects of corn mouse population dynamics. Restricting control measures to when mouse numbers reach high levels would be inadequate, because population numbers tend to increase in size after some years. In contrast, reducing vegetation cover in spring was more effective in reducing field population abundances. Despite some limitations, the model could be useful for evaluating the relationships between population dynamics and some biotic or physical environmental variables, and thus ensure more efficient use of resources in integrated pest management.     

Outbreaks and Damage by the Field Vole,Microtus agrestis (L.), since World War II in Europe1

The field vole, Microtus agrestis (L.), is a major pest in horticulture and forestry in all Scandinavian countries, and an important forestry pest in certain regions in central Europe. The most common type of damage is girdling trunks of cultivated trees, usually under the snow cover. In horticulture, the apple tree is the commonest subject of injury, while, in forestry, several deciduous and conifer species are attacked. In Finland and Norway, the garden industry has suffered most, while, in Sweden, the problems are predominantly in forestry. In central Europe, M. agrestis is a forestry pest only. Summation of all losses due to the field vole since World War II amounted to somewhere between 50 and 100 million US Populations of M. agrestis normally undergo cyclic fluctuations. However, comparison of the periodicity of outbreaks in different areas reveals variations, 3 to 4-year intervals dominating in the Scandinavian countries, while the interval in central Europe is generally somewhat shorter. No overall synchrony exists over the geographical range of the species. Present knowledge concerning the demography and habitat dynamics of M. agrestis is briefly reviewed. Current possibilities for preventing damage by M. agrestis are much dependent on the individual value of the potential subjects of injury. High value stands, like apple gardens or seed orchards of forest trees, can be protected by means of mechanical guards. However, current means of combating damage in forest plantations are badly limited. Surface spraying with toxaphene and poison baits is practised in central Europe, while, in the Scandinavian countries (except Denmark), no chemical means are used today. Development of new compounds to be used as surface sprays, or specific baits for M. agrestis, is urgently needed. Research on bio-control methods should also be intensified.     

The sensitivity of simulation models to temperature changes1

Insect population processes, such as development and reproduction, are dependent upon temperature. Accurate predictions of the phenology and population dynamics of insect pests require accurate recording of the temperatures experienced by the organisms. Any errors in the temperature measurements may result in spurious estimates of the pest population and, therefore, poor quality advice on the necessary control strategies. A simulation model predicting the phenology and population dynamics of the summer fruit tortrix, Adoxophyes orana, will be described. Output from the model closely resembled field observations of the population dynamics of the pest. Experimentation with the model revealed its sensitivity to small changes of temperature. The results illustrate the importance of using input recorded realistically with respect to the biology of the pests.     

Common vole (Microtus arvalis) ecology and management: implications for risk assessment of plant protection products

Common voles (Microtus arvalis) are common small mammals in some European landscapes. They can be a major rodent pest in European agriculture and they are also a representative generic focal small herbivorous mammal species used in risk assessment for plant protection products. In this paper, common vole population dynamics, habitat and food preferences, pest potential and use of the common vole as a model small wild mammal species in the risk assessment process are reviewed. Common voles are a component of agroecosystems in many parts of Europe, inhabiting agricultural areas (secondary habitats) when the carrying capacity of primary grassland habitats is exceeded. Colonisation of secondary habitats occurs during multiannual outbreaks, when population sizes can exceed 1000 individuals ha^?1. In such cases, in‐crop common vole population control management has been practised to avoid significant crop damage. The species' status as a crop pest, high fecundity, resilience to disturbance and intermittent colonisation of crop habitats are important characteristics that should be reflected in risk assessment. Based on the information provided in the scientific literature, it seems justified to modify elements of the current risk assessment scheme for plant protection products, including the use of realistic food intake rates, reduced assessment factors or the use of alternativee focal rodent species in particular European regions. Some of these adjustments are already being applied in some EU member states. Therefore, it seems reasonable consistently to apply such pragmatic and realistic approaches in risk assessments for plant protection products across the EU. © 2013 Society of Chemical Industry     

Spatial aggregation in Fusarium pseudograminearum populations from the Australian grain belt

Previous studies have evaluated the overall structure of populations of Fusarium pseudograminearum (teleomorph, Gibberella coronicola ), causal agent of cereal crown rot, but there is no information available on spatial relationships of genetic variation in field populations. Three 1-m-row sections in crown-rot-affected wheat fields in the Australian grain belt were intensively sampled to estimate population genetic parameters and the spatial aggregation, or clustering, of disease aggregates and genotypes. Estimates of population genetic parameters based on amplified fragment length polymorphisms (AFLPs) indicated that the genetic diversity in isolates from the 1-m-row populations described a significant portion of the diversity recorded for corresponding field and regional populations. In point pattern analysis, there was physical clustering and aggregation of F. pseudograminearum isolates from two of the three sites. Analysis of the spatial distribution of clonal haplotypes (DICE similarity ≥ 97%) indicated significant aggregation of clones in all three 1-m-row populations. Based on matrix comparison tests, both mating types and genetic distances had significant spatial aggregation for at least two of the three 1-m-row populations. This is consistent with the presence of non-random spatial genetic structure due to clonal aggregation. High levels of genetic diversity and spatial structuring of disease and genotypes in at least two of the three 1-m-row populations is consistent with the hypothesis that stubble is a primary inoculum source in no-tillage farming systems, resulting in aggregated patterns of disease and allowing for haplotypes to be maintained in the field over a number of annual cropping cycles.     

Modelling population dynamics of Sinapis arvensis in organically grown spring wheat production systems

Although we know that alterations in crop density, crop spatial pattern and inclusion of more selective weed control can improve weed suppression for organic growers, it is unknown whether these result in changes to the weed seedbank that increase cropping system profitability over time. Data collected from field trials conducted in 2009 and 2010 in Maine, USA, comparing regional grower practices (Standard) with management that aimed to (i) facilitate better physical weed control through the use of wide row spacing and inter‐row cultivation (Wide) or (ii) enhance crop–weed competition through increased seeding rate and narrow inter‐row spacing (Narrow HD), were used to construct a matrix population model with an economic sub‐model. Using field measurements of grain yield and weed survival and fecundity, we investigated the lasting implications of employing alternative organic spring wheat (Triticum aestivum) production practices on Sinapis arvensis population dynamics. In most scenarios, the model indicated that regional production practices were not sufficient to prevent an increase in the weed seedbank, even with excellent weed control. The two alternative methods, on the other hand, were able to limit weed population growth when initial densities were low or cultivation efficacy was >80%. Due to higher seed costs in the Narrow HD system, net returns were still lower after 10 years of simulation in this system compared with wide rows with cultivation, despite a lower weed seedbank.     

Development of a simulation model for the population dynamics of the onion fly Delia antiqua in Germany*

Delia antiqua is a serious pest of many species of the genus Allium, including onions and chives. Over a period of two years (1997/1999), we have developed a model to simulate the population dynamics of D. antiqua based on an extended Leslie model. The model structure as well as the developmental functions for the different life stages of D. antiqua are presented. Using daily mean air and soil temperatures, the model calculates the population matrix for developmental stages of D. antiqua including eggs, larvae, pupae and adults. The simulation can be used to optimize the timing of control measurements against a specific life stage of D. antiqua. Flight activity can be simulated using wind speed as additional information. Simulated flight activity and the observed flight activity of D. antiqua monitored with water pan traps in three different regions of Germany in 1998 are presented and discussed. The model, which was programmed as part of the SWAT 3.5 package of programs to simulate the population dynamics of root‐fly pests in horticultural crops, will also be available via other expert systems such as PASO.     

Prognose von Wühlmaussch?den in Forstkulturen

Zusammenfassung  In den Jahren 1980–1990 wurden auf insgesamt 100 Probefl?chen Wühlmausf?nge für die Schadensprognose in Forstkulturen durchgeführt. Die gefangenen Tiere wurden im Labor eingehender untersucht und verschiedene Parameter mit der Dichteentwicklung der Schadnager verglichen. Für einen beschr?nkten Zeitraum von etwa 3 Monaten war die ?u?erlich me?bare L?nge der m?nnlichen Gonaden mit der Populationsentwicklung korreliert. Bei einer mittleren L?nge der Testes über 3,5 mm wurde eine Zunahme der Populationsdichte beobachtet (Gradation). Bei einer geringeren Gonadenl?nge war die Populations-entwicklung rückl?ufig (Retrogradation). Dieser Zusammenhang kann für eine Schadensprognose bedeutsam sein.

---

Predicting damages of voles in forest cultivations

Voles like the Field VoleMicrotus agrestis, the Common VoleM. arvalis, the Bank VoleClethrionomys glareolus and the Water VoleArvicola terrestris can cause severe damages in forest cultivations by gnawing the trunks and the roots of the young trees. Damages occur during winter time when the population density of these species is high and food resources are limited. The forecast of the development of vole populations is needed to prepare countermeasures against vole damages. The increase or decrease of a vole population can be predicted, if the fertility of the caught specimens is observed. The gonadal size of the males was a suitable predictor for the trend of the development of a vole population. The change of population density of the Bank Vole in a time interval of 3 month (September–December) was highly correlated (r=0.86) with the gonadal index of males. The percentage of pregnant or lactating femals was also a good indicator, but less suitable for practical use. It is assumed, that the hormones of the hypophysis like FSH, LH and Prolactin rule the growth of the gonads, the fertility and the reproduction in a vole population. Testis size is an indicator for the activity of these fertility hormones and for the reproductive process. It can be used to predict the development of vole populations for a limited time interval.

     

The Basis of Predictive Modelling for Estimating Yield Loss and Planning Potato Cyst Nematode Management

The basis of modelling yield loss and population dynamics relations of potato cyst nematodes is that both are strongly density-dependent. Potato cyst nematodes (PCN; Globodera pallida and G. rostochiensis) are particularly suitable for analysing such relationships because they have only one generation per year, potato is their only field host, the juvenile nematodes within the egg are very durable (up to 20 years persistence), and they hatch mainly in response to specific chemicals exuded from host roots. Small populations increase the most, up to 50-fold, when a potato crop is grown. Multiplication rates decrease as the population density increases because damage decreases root system size and increases competition so that very large populations may actually be decreased when potatoes are grown. The newly formed eggs have a ‘half-life’ of c.two years when non-host, rotational crops are being grown. Control is achieved largely by the use of rotation, the application of nematicidal chemicals, and growing resistant cultivars. As rotations are shortened, so PCN populations will be increased, and crop damage becomes more likely. Thresholds for damage vary with both soil type (greatest on sandy soils) and potato cultivar. Cultivars differ in their tolerance of PCN damage depending on how vigorously they grow, on their root sensitivity to damage from the PCN juveniles which invade close to root tips, on cultivar resistance which decreases the parasitic effect by reducing the numbers of developing PCN females, and on various environmental factors such as the amounts of fertiliser applied. The dependence of the yield-loss relationship on population density, soil type and cultivar effects has been described in a simple equation and assessed using field-trial data. Effects on yield are described in proportion to the PCN-free yield but the addition of information on expected yield (in tonnes ha⁻¹) in the absence of PCN renders this equation predictive. Nematicides are widely applied to infestations of potato cyst nematodes, both to prevent the crop from being damaged and to prevent population increase which could hazard the next potato crop in the rotation, but they are generally more effective at preventing the former than the latter. A complex equation has also been developed to model the population dynamics of PCN. This equation incorporates a factor for host-crop growth and tolerance (from the yield-loss equation) and also the effects of host resistance. This latter is particularly relevant to G. pallida, where all the resistance currently available is determined by minor genes and hence is ‘quantitative’ or ‘partial’. Effects of rotation and of nematicides can also be incorporated into this model. To provide a realistic prediction also requires accurate information on PCN population densities, species composition and distributions, and rates of PCN population decline between potato crops.     

Genotypic diversity in Fusarium pseudograminearum populations in Australian wheat fields

Despite being closely related to Fusarium graminearum, which has been extensively characterized in many countries around the world, the population biology of Fusarium pseudograminearum, the main causal agent of crown rot of wheat in Australia and many other wheat‐growing regions, has been comparatively poorly studied to date. A simple sequence repeat analysis of 163 F. pseudograminearum isolates from three field sites in NSW, Australia identified 128 distinct multilocus genotypes. Observed genetic diversity within fields was high, whilst genetic variation between fields was low. Across all fields genetic linkage disequilibrium was detected, but of the three individual fields, only one also displayed linkage disequilibrium. These results indicate that the isolates obtained were part of the same, highly diverse, population. However, this population may not be freely interbreeding. Whilst isolation incidence of F. pseudograminearum was found to be spatially aggregated within fields, spatial aggregation of genotypes within fields was weak. The study suggests that processes influencing population dynamics may operate at a scale larger than the narrow geographical scale covered in the fields sampled.     

Quantifying inherent predictability and spatial synchrony in the aphid vector Myzus persicae: field-scale patterns of abundance and regional forecasting error in the UK

Background

Sugar beet is threatened by virus yellows, a disease complex vectored by aphids that reduces sugar content. We present an analysis of Myzus persicae population dynamics with and without neonicotinoid seed treatment. We use 6 years' yellow water trap and field-collected aphid data and two decades of 12.2 m suction-trap aphid migration data. We investigate both spatial synchrony and forecasting error to understand the structure and spatial scale of field counts and why forecasting aphid migrants lacks accuracy. Our aim is to derive statistical parameters to inform regionwide pest management strategies.

Results

Spatial synchrony, indicating the coincident change in counts across the region over time, is rarely present and is best described as stochastic. Uniquely, early season field populations in 2019 did show spatial synchrony to 90 km compared to the overall average weekly correlation length of 23 km. However, 70% of the time series were spatially heterogenous, indicating patchy between-field dynamics. Field counts lacked the same seasonal trend and did not peak in the same week. Forecasts tended to under-predict mid-season log₁₀ counts. A strongly negative correlation between forecasting error and the proportion of zeros was shown.

Conclusion

Field populations are unpredictable and stochastic, regardless of neonicotinoid seed treatment. This outcome presents a problem for decision-support that cannot usefully provide a single regionwide solution. Weighted permutation entropy inferred that M. persicae 12.2 m suction-trap time series had moderate to low intrinsic predictability. Early warning using a migration model tended to predict counts at lower levels than observed. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

黄土高原农牧交错带退耕坡地苜蓿-铁杆蒿群落养分分布特征

植物群落养分的空间分布反映了生态系统物质循环特征,可以为揭示生态系统资源的有效性及生态系统中植物群落的演替过程提供依据。本研究以黄土高原农牧交错带退耕坡地苜蓿-铁杆蒿群落为对象,分析其生物量和养分含量的空间分布特征。结果表明:退耕地苜蓿-铁杆蒿群落坡上部以苜蓿为主导物种,坡下部以铁杆蒿为主导物种,坡中部由二者共同主导。同一植物的生物量和N含量具有相似的空间结构,并且与植物种类有关;苜蓿和铁杆蒿P含量均以球状模型最佳,K含量的空间分布均以高斯模型最佳。苜蓿-铁杆蒿群落生物量和养分含量具有较强的空间依赖性,其空间变异主要由结构性因素决定。苜蓿和铁杆蒿生物量和养分含量的自相关性随距离变化表现出相似的趋势,但随生物量和养分种类的不同而异,且铁杆蒿生物量和养分含量的自相关性大于苜蓿。随着人工草地向天然草地的演替,群落生物量和养分含量的空间自相关性和空间依赖性逐渐增强。     

Outbreak of Arvicola terrestris in rice fields in Yugoslavia1

Macedonia is the southern boundary for the distribution of Arvicola terrestris (water vole) in the Balkan peninsula. Until recently, these voles were found in the region only sporadically, showing none of the cyclic population fluctuations characteristic of microtines in the continental part of Europe. An investigation was started in 1984 when the first visible signs of damage to rice in Ko?ansko Valley, caused by numbers of voles, were noted. Since then, population numbers have increased, reaching a density of 1000 individuals per ha on one locality. The causes of such an unexpected outbreak and the methods for determining role abundance are discussed. The construction of a dam and the extension of rice cultivation have reduced the natural habitats of both vole predators and their competitors. Increased pesticide and fertilizer usage have also affected the fauna unfavourably. Efficient control was attained by means of zinc phosphide baits, specially before the rice growing season (i. e. in winter and early spring).     

The use of thermal calendar models to improve the efficiency of herbicide applications in Sorghum halepense (L.) Pers

The dynamics of sprout emergence and rhizome populations of Sorghum halepense (L.) Pers. were followed in two field experiments. In addition, the herbicide dalapon was applied at various stages during rhizome development and the degree of control was evaluated. Rhizome biomass oscillated during the growth cycle, whereas the number of rhizome sprouts increased asymptotically until mid-summer. Observed values were compared against those predicted from a thermal calendar model. The dynamics of the rhizome population was predicted accurately in both experiments, but only in one of them was the prediction of the sprout emergence satisfactory. The degree of control differed markedly between herbicide applications at various intervals during population development. Best results were obtained from applications when rhizome biomass was at a minimum. The time of minimum biomass was predicted by a thermal calendar model. The advantages of using the thermal calendar model to determine the time of herbicide application, and the possible influence of the distribution of the rhizome population in the soil profile on the predictions of the model, are discussed.     

Distribution of race-specific resistance against <Emphasis Type="Italic">Bremia lactucae</Emphasis> in natural populations of <Emphasis Type="Italic">Lactuca serriola</Emphasis>

A metapopulation approach was applied to population studies of a common weed, Lactuca serriola (prickly lettuce). Seedlings grown from seed samples collected from 752 individual L. serriola plants in 50 populations occurring along an east-to-west transect across four European countries (Czech Republic, Germany, Netherlands and United Kingdom) were screened for resistance to 10 common races of Bremia lactucae. Based on the recorded reaction patterns, host individuals were characterized into specific resistance (R-) phenotypes. Diversity of R-phenotypes, their variation and distribution among and within European populations, was evaluated at different spatial scales, i.e. from a metapopulation involving the entire European study area to individual plants occurring in local populations. Generally, European populations of L. serriola have been shown to be highly susceptible to B. lactucae. However, large variation in L. serriola resistance was found both among and within individual countries. There was a clear gradient of increasing uniformity of race-specificity moving from central to western Europe, as well as a slight decrease in the diversity of R-phenotypes. Populations in the United Kingdom were the most divergent in terms of resistance structure from other geographic regions, and also were the most homogeneous, most likely a consequence of the relatively greater degree of spatial isolation from other regions. Metapopulation, inter- and intra-population variation in host resistance is discussed from the viewpoint of occurrence of race-specific interactions in this wild plant pathosystem.     

用逐步判别法进行二化螟中长期数量预测

本文采用贝叶斯(Bayes)准则下的逐步判别分析法,对影响二化螟种群变动的因素进行筛选,建立起中长期数量预测模式(判别函数),并讨论了该测报方法的若干特点     

Note: Fluctuations in population of the first recorded predatory fly<Emphasis Type="Italic">Coenosia attenuata</Emphasis> in cotton fields in Turkey

The occurrence of the predatory flyCoenosia attenuata (Stein, 1903) is reported for the first time in Turkey. The population dynamics of the fly in irrigated cotton fields in the eastern Mediterranean region of Turkey is described, and the role ofC. attenuata as a biological control agent in the agroecosystem is discussed. http://www.phytoparasitica.org posting Sept. 30, 2003.