Relative influence of climate and agroenvironmental factors on wireworm damage risk in maize crops

A large-scale survey was carried out in 336 French fields to investigate the influence of soil characteristics, climate conditions, the presence of wireworms and the identity of predominant species, agricultural practices, field history and local landscape features on the damage caused by wireworms in maize. Boosted regression trees, a statistical model originating from the field of machine learning, were fitted to survey data and then used to hierarchize and weigh the relative influence of a large set of variables on the observed damage. Our study confirmed the relevance of an early assessment of wireworm populations to forecast crop damage. Results have shown that climatic factors were also major determinants of wireworm damage, especially the soil temperature around the sowing date, with a strong decrease in damage when it exceeds 12 °C. Soil characteristics were ranked third in importance with a primary influence of pH, but also of organic matter content, and to a lesser extent of soil texture. Field history ranked next; in particular, our findings confirmed that a long-lasting meadow appeared favourable to wireworm damage. Finally, agriculture practices and landscape context (especially the presence of a meadow in the field vicinity) were also shown to influence wireworm damage but more marginally. Overall, the predicted damage appeared highly correlated with the observed one allowing us to produce the framework of a decision support system to forecast wireworm risk in maize crop.     

Categorization and numerical assessment of wireworm mobility over time following exposure to bifenthrin

We discuss the effect of the pyrethroid insecticide bifenthrin incorporated into soil at 100, 200, and 300 g AI/ha on late-instar larvae of the dusky wireworm, Agriotes obscurus (Coleoptera: Elateridae), and present a method of assessing wireworm health and mobility over time. Wireworms became moribund within 1 h of placement in soil amended with bifenthrin at all rates. After 2 weeks of morbidity in amended soils, wireworms recovered within 7 days of being placed in clean soil. A considerable proportion (0.13–0.93) of wireworms placed in amended soil moved to the soil surface and remained there for 2 weeks or more in a moribund state; wireworms transferred to clean soil no longer moved to the soil surface. Eight distinct mobility categories were observed and are described, and a new method for assessing wireworm health and mobility over time is discussed.     

Wireworm damage reduction in potatoes with an attract-and-kill strategy using <Emphasis Type="Italic">Metarhizium brunneum</Emphasis>

Innovative wireworm control strategies are required to implement integrated pest management on the basis of the (EC) No regulation 1107/2009 and Directive 2009/128/EC. Entomopathogenic fungi, such as Metarhizium brunneum (Metschnikoff) Sorokin, are potential biological control agents for wireworm control but do not achieve high control efficacies in the field when applied as a conidia suspension. In a 2-year study, wireworm control with a novel attract-and-kill strategy aimed at enhancing M. brunneum efficacies in organic potato production systems in Lower Saxony, Germany. The approach is based on the attraction of wireworms (Agriotes spp. Eschscholtz) towards an artificial carbon dioxide-emitting source, using baker’s yeast (Saccharomyces cerevisiae Meyen ex Hansen) in combination with M. brunneum conidia for wireworm infection. Both components were encapsulated in alginate as a carrier material and applied in a mixture with two types of beads (one for encapsulated yeast and one for M.brunneum conidia). An application of these beads within the potato rows during potato planting reduced wireworm tuber damage by 37–75% relative to the untreated control and was able to enhance the efficacy of M. brunneum by up to 35% through an attract-and-kill approach compared to beads without a carbon dioxide source only. This strategy offers a high potential to promote biological wireworm control as an alternative to insecticide use by potentially reducing the inoculum compared to an inundate M. brunneum conidia release strategy.     

“Uradome” treatment for prevention of snow damage and terrain parameters of moso bamboo (Phyllostachys pubescens) forest in Tsuruoka,Yamagata Prefecture

Moso bamboo (Phyllostachys pubescens) is cultivated for edible bamboo shoot production in Japan. Yamagata Prefecture is located in a heavy-snowfall region at the northern limit of the cultivated area. However, snow damage to bamboo culms occurs every year and decreases bamboo shoot production. “Uradome” is a treatment that involves cutting off the upper portion of the new culms when the bamboo shoot is almost fully grown. We studied the effect of “Uradome” implementation on incidence of snow damage to bamboo culms. In addition, we investigated terrain characteristics of bamboo forest at sites where snow damage occurred. As a result, the higher the degree of “Uradome” was, the lower the damage rate was. Furthermore, the results revealed that implementation of “Uradome” prevents snow damage to culms. It is considered that snow damage may be prevented by rendering the culm shape straight as a result of “Uradome”. The results also indicated that snow damage is more likely to occur on steep slopes. Factors that influence the incidence and severity of snow damage are considered to differ between Japan and other countries. Therefore, it is desirable to adopt preventative measures against snow damage, such as the “Uradome” method, irrespective of the local climate and terrain.     

Preliminary investigations into the use of trap crops to control Agriotes spp. (Coleoptera: Elateridae) in potato crops

A field trial was conducted to investigate the use of peas (Pisum sativum cv. Valverde), wheat (Triticum aestivum cv. Capo) and oilseed radish (Raphanus sativus var. oleiformis cv. Adagio) as trap crops to control wireworm in potato fields. We investigated the efficacy of trap crops and distance of attraction by counting larvae in both potato and trap crop rows. Wireworms of the genera Agriotes, Adrastus and Hemicrepidius were observed. In the plots planted with peas as a trap crop, significantly more wireworms were observed than in the other treatments, which was clearly due to the influence of the trap crop pea. The potato rows 0.75 m away from the peas showed 2.4 times more larvae than the potato rows 1.5 m away. This may be due to a decrease of the peas’ attractiveness over time (Miles and Petherbridge 1927), with wireworms that were initially attracted to the peas moving back to the nearby potatoes. In the plots planted with wheat, oilseed radish and the control (bare soil instead of a trap crop), there was no significant difference in numbers of larvae between the potato rows. In the control plots, significantly more larvae were found in the potato rows than in the bare soil. We assessed the damage to potato tubers by weighing them and counting the wireworm holes. Our results indicate that peas are more attractive to wireworms than potatoes and might be an effective trap crop if the right timing and spacing relative to the potatoes is found.     

Wireworm damage to wheat seedlings: effect of temperature and wireworm state

We describe the results of four laboratory studies designed to measure the effect of temperature and wireworm appetence, weight, and degree of Metarhizium infection on their ability to damage wheat seedlings. Wireworm activity, measured from wireworm speed, increased linearly from 6 to 18 °C and leveled off thereafter. Plant emergence and growth increased exponentially from 6 to 22 °C for wheat cultivars AC Barrie and AC Unity VB. Plant root:shoot ratio at Zadoks 13 was highest at 14 °C and lowest at 22 °C for AC Barrie. Wireworm weight and degree of infection with Metarhizium did not affect their ability to kill wheat seedlings, but wireworms in a feeding state caused significantly more damage than those in a non-feeding state when wheat was grown at 10, 14, 18, and 22 °C. Wireworms (ww) in a feeding state destroyed 1.8 seedlings/ww in 14 days at 22 °C if there were 1 or 2 wireworms in a pot, and 1.5 seedlings/ww if there were 4 wireworms in a pot. If 5 wireworms were placed in a pot, wireworms in a feeding state destroyed 0.3, 1.0, 0.9, 1.3, and 1.4 seedlings/ww in 46, 32, 25, 25, and 25 days at 6, 10, 14, 18, and 22 °C, respectively. Wireworm mortality from Metarhizium during 60 days of containment in pots in the study was higher in non-feeding than in feeding wireworms, and higher if wireworms were selected from a Metarhizium-infected colony than those selected from a non-infected colony. Some of the implications of these results for wireworm management and laboratory trials are discussed.     

“一分钟游程”构园法则的适用性研究

“一分钟游程”构园法则将人的视觉感受与园林组景共同考虑,以25~30 m作为组景转换的理想距离,对游路结构进行反复烘托与不断强化,从而形成柔和、丰富的“构景曲线”。选择南北方各具代表性的苏州沧浪亭和北京恭王府花园,分析其园林的景观布局,对比园林空间序列的“起”“承”“转”“合”间距。结果表明,“一分钟游程”构园法则在南方私家园林及北方皇家园林中同样适用,为今后的游线组织与组景布设提供了设计参考。     

Response of the dusky wireworm, Agriotes obscurus (Coleoptera: Elateridae), to residual levels of bifenthrin in field soil

To determine if bifenthrin residues elicit morbidity and surfacing behavior in wireworms, larvae of the dusky wireworm, Agriotes obscurus (Coleoptera: Elateridae) were placed in field soil treated with the pyrethroid insecticide bifenthrin ~1 year previous. Morbidity was immediate and lasted as long as wireworms remained in the soil, disappearing quickly after transfer to clean soil. In 2009, field soil treated 336 days previous with bifenthrin at 340 g AI/ha elicited morbidity symptoms similar to that elicited by soil freshly amended with bifenthrin at 100 g AI, and analysis of the field soil confirmed residual levels of bifenthrin exceeding 100 g AI/ha. In 2010, wireworms placed in field soil treated 343 days previous with bifenthrin at 100, 200, and 300 g AI/ha responded as in 2009, with the degree of morbidity increasing with the rate of insecticide, and with wireworms in a non-feeding state more affected than those in a feeding state at each rate. In both 2009 and 2010, moribund wireworms moved to the soil surface within 1 day of placement in the soil containing residual bifenthrin and remained there until reburied, after which they often resurfaced. To confirm that the bifenthrin residues elicited repellency, wireworms were placed in soil window bioassays containing field soil with residual bifenthrin. Wireworms behaved markedly different upon contacting soil containing the residues than when exposed to untreated soil, both in the presence and absence of an attractant, but were less likely to avoid soil containing residual bifenthrin when attracted by wheat seedlings placed inside it.     

IPM thresholds for Agriotes wireworm species in maize in Southern Europe

Currently, integrated pest management (IPM) of wireworms is not widespread in Europe. Therefore, to estimate the densities of three major wireworm species in southern Europe (Agriotes brevis Candeze, A. sordidus Illiger, and A. ustulatus Schäller), bait traps were deployed pre-seeding in maize fields in north-eastern Italy between 1993 and 2011. Research discovered that there was a significant correlation between all three wireworm species caught in the bait traps and damage to maize plants, but damage symptoms varied. Wherever A. ustulatus was the main species caught, there was no significant damage to maize plants, but seeds were damaged. Most of the symptoms caused by A. brevis and A. sordidus were to the central leaf/leaves, which wilted because of feeding on the collar. A. brevis was the most harmful species; when more than one A. brevis wireworm was caught per trap, plant damage sometimes resulted in reduced yield. Five A. ustulatus larvae per trap caused the same damage to maize as one A. brevis. A. sordidus came second (threshold two larvae/trap). These thresholds are reliable for: (1) bare soil in which there are no alternative food sources; (2) average soil temperature 10 cm beneath the surface of above 8 °C for 10 days; (3) soil humidity near to field water capacity, but days of flooding have not been considered. The implementation of the practical method described herein may lead to effective IPM of wireworms in maize and to a significant reduction in the number of fields treated with soil insecticides.     

Crop protection and mortality of Agriotes obscurus wireworms with blended insecticidal wheat seed treatments

In Canada, as in much of the northern hemisphere, insecticidal seed treatments for cereals that both protect crops from damage by wireworms (Coleoptera: Elateridae) and actually reduce wireworm populations to sub-economic levels are lacking. Thiamethoxam and fipronil applied alone or in combination as wheat seed treatments were evaluated in field studies between 2006 and 2008 in protecting wheat from damage and reducing populations of resident and neonate wireworms. Thiamethoxam alone applied at 5 or 10 g a.i./100 kg seed provided adequate wheat stand and yield protection, but did not significantly reduce Agriotes obscurus wireworm populations. Fipronil alone at 5–50 g a.i./100 kg seed provided adequate wheat stand and yield protection, and also killed significant numbers of both resident and neonate wireworms. Thiamethoxam (10 g a.i.) was initially combined with fipronil at 50, 5, 0.5, 0.05, and 0.005 g a.i./100 kg seed, and subsequently with a delimiting range of fipronil at 50, 5, 1, 0.5, and 0.1 g a.i. Blends of thiamethoxam (10 g a.i.) + fipronil at rates of 50, 5, or 1 g a.i. provided stand and yield as good or better than the former industry standard Vitavax Dual (containing lindane). Combinations of thiamethoxam (10 g a.i.) + fipronil at rates of 50, 5, 1, and 0.5 g a.i. had very low numbers of resident or neonate wireworms relative to the untreated check and were comparable to the Vitavax Dual standard. The benefit of combined thiamethoxam + fipronil seed treatments at these rates, is that crop stand and yield are improved over the individual chemicals applied alone, and resident and neonate wireworm mortality is high. The large reductions in resident and neonate wireworms observed with these combined seed treatments would remove the economic threat of wireworms in fields for 3+ years with rates of insecticides much lower than the formerly used Vitavax Dual.     

Land use alters the abundance of herbivore and predatory insects on crops: the case of alfalfa

We assess the effects of changing land use and crop management on alfalfa insect abundance by comparing it in 50 alfalfa fields when they were inserted in landscapes with different proportions of arable crops and orchards. Land use in a buffer of 500 m was assessed, and alfalfa insect abundance was estimated with sticky yellow traps. The number of catches of several herbivores and predators was related to the proportion of landscape components and several field variables. Results indicated that the proportion of orchards in the buffer negatively affected the abundance of predators on alfalfa, likely because orchards treated with pesticides are a sink for predators moving in the landscape, among other possible causes. Other landscape variables such as noncrop habitats, winter cereals, and landscape diversity analysed by the Shannon index had a minor influence. Among field variables, field size influenced positively the abundance of insects on alfalfa, whereas alfalfa growth stage and age affected positively or negatively the different herbivores and predators. Of course, abundance of predators and prey was affected by the abundance of prey and predators, respectively. These findings suggest that a high proportion of intensively managed crops (orchards) in the landscape interferes with the role of alfalfa as a reservoir of predatory insects for adjacent crops and that the responses to local and landscape structures are temporal and species-specific as previously concluded for maize. Consequently, landscape and field management strategies to improve pest control must consider both types of variables as well as their changing influence when we modify them.

     

基于眼动的城市森林景观视觉质量评价及距离变化分析

文章基于注视点个数、注视频率、平均注视时间、平均眼跳幅度、平均眼跳速度、首次注视时间、注视时间比重7个眼动指标,构建景观视觉质量评价模型,选取并拍摄获取通州运河森林公园旱柳林5个样地、6个不同距离梯度下的30个样本,通过眼动实验获取指标数据进行景观视觉质量评价;再基于ANOVA分析距离对景观视觉质量的影响,并根据研究结果提出旱柳林游憩步道建设对策。研究结果表明:1)旱柳林景观视觉质量值分布在0.13~1.49范围内,90%样本处于中高等级,视觉质量较好;2)注视点个数、注视频率、平均眼跳幅度、注视时间比重对景观视觉质量构成显著影响,距离变化通过显著影响注视点个数,对注视频率、平均眼跳幅度、注视时间比重产生相关影响,从而影响景观视觉质量;3)旱柳林景观视觉质量在25 m处最低,且25 m处视线多向树冠与草坪交界面聚集,草坪对景观感知存在一定影响,在5 m和30 m处景观视觉质量呈现相对较高水平,可作为游憩路径设置参考值。     

Monitoring spruce bark beetle (Ips typographus (L.)) populations under non‐epidemic conditions

Population levels of Ips typographus in 8 Danish forest districts were monitored by pheromone traps and baited trees in 1988 and 1989. The number of trees with spontaneous colonization was also registered. All monitoring results were below earlier defined “risk thresholds”;, and accordingly no serious damage was found. Mean catch ranged from 3406 to 12043 beetles per trap group, and induced colonization averaged 1.08 trees per tree‐baiting site. Trie number of colonized trees (total infestation) ranged from 3.5 to 63.2 trees per 100 ha forest. Correlation was found between mean catch and induced colonization (r=0.56), and between induced colonization and total infestation (r=0.65). Accumulated data from 1988–89 and 1984–86 showed good correlation between catch size and number of infested standing trees (r=0.91). From 1988 to 1989 no significant changes occurred, apart from a shift in host material from standing trees to windfalls and timber. I. Typographus monitoring on regional levels is possible also under non‐epidemic conditions. With a limited number of monitoring units, trapping, tree‐baiting and registrations of infestation in exposed edges can give estimates sufficiently accurate to be of practical use to local foresters.     

Recent spruce decline with biotic pathogen infestation as a result of interacting climate,deposition and soil variables

Decline or health deterioration of Norway spruce (Picea abies (L.) Karst.) dominated forest stands has recently been observed mainly in sub-mountainous parts of Central Europe. Forest inventory of 208 randomly distributed circular plots including field observations of spruce tree health and rot symptoms by honey fungus (Armillaria ostoyae) was used for assessing intensity of spruce forest health decline in a managed forest area of 12.7 th. ha located in Beskids Mts., NE Czech Republic. First, principal component analysis was used to separate inventory variables related to environmental stress (reduced apical increment, dry tree top and stem resin exudation due to A. ostoyae infestation) into PC1, and health deterioration symptoms associated with mechanical damage (peeling, crown breaks) into PC2. The first two principal components explained 59% of the total variability in health decline symptoms. Spatial variability of both principal components was explained using spatial lag regression model identified from a set of environmental variables including sulfur and nitrogen deposition, elevation, solar radiation, age of the forest stands and geological properties (geochemical reactivity index). Environmental stress (PC1) was associated with low elevations (sub-optimal for spruce), high level of nitrogen and sulfur deposition (their interaction), low geochemical reactivity and also stand age. On the other hand, mechanical damage (PC2) significantly increased with elevation and stand age. As the forest decline in Beskids Mts. is related to A. ostoyae spreading from local infestation hot spots, both principal components had a significant spatial autocorrelation, partly distorting the signal of environmental conditions. The results indicate that the disturbed forest soils by long-term acid deposition and subsequent nutrient degradation and more pronounced drought stress at low elevations are the most important drivers of the recent spruce health decline in Beskids Mts.     

和林格尔县郁松园公墓景观规划设计

为了改善当代城市公墓分布随意、形式简陋,且易对景观环境造成视觉污染的状况,采用实地勘察和文献研究的方法,对和林格尔县郁松园公墓景观进行详细的规划设计,以打造生态环保的感悟性空间为主导思想,通过合理化利用地形、带入当地人文元素、景观空间的情感化处理等园林设计手法,利用"一轴三点四区"的整体景观布局形式对全园进行结构性的区域划分,重点在于利用不同的竖向场地类型来塑造各具特色的现代化墓区景观,将景观与生态融为一体,旨在打造出符合"美丽中国""生态文明"理念的新型墓园景观。     

泉州海港城市地域性景观特征与保护

文章选取有“三湾十二港”之称的泉州地区作为研究对象,运用野外调查、文献归纳和图形分析的方法梳理泉州地区所特有的“山水-聚落-风景”的地域性景观风貌特征,进而探讨在城市化进程中所面临的问题并提出相应的海港城市地域性景观的保护策略。     

Die Nonne (Lymantria monacha L.) in Nordwestdeutschland 1977–1980

The outbreak of Non Moth (Lymantria monacha L.) in northwestern Germany during 1977/1980 took place in several distinct infestation areas. Most of them could be kept small by well timed chemical control. In 1978 983 ha were treated with Dimilin 25 WP by air (combined treatment against pine beauty moth), in 1979 332 ha, and in 1980 292 ha, i. e. a total of 1610 ha. Further applications on 48 ha were made with biological agents (NPV,Bac. thuringiensis) for experimental purpose. Particular importance is attributed to monitoring and surveying of the Nun Moth. Methods used are described and discussed. Empirical data show Nun Moth gradations to start often at certain distinct centers. Knowledge of the special characteristics of those outbreak centers is required for effective surveying. Our experiences in 1977/80 are compared with older ones collected over the last 120 years in NW Germany. One remarkable feature seems to be the consistent occurrence of japanese or european larch in our recent infestation centers. The spreading of damage and the recovery of the affected stands could be seen in plots treated with biological preparations. The results confirm the earlier experiences that norway spruce generally is getting rapidly killed by defoliation while scots pine may recover even after severe damage. Larch normally survives even more than one complete loss of its needles.     

西安市花灌木植物病害种类调查补充名录

通过对西安市城区花灌木病害发生情况进行全面普查研究,调查受害植物74种。对比以往相关资料记载,新发现花灌木病害种类243种。本次补充名录共新记载病害115种,其中细菌病害1种,生理病害1种,植原体病害1种,线虫病害1种,真菌性病害111种,真菌病原菌分属于32属。通过本次调查基本明晰了当前西安市绝大多数园林花灌木病害类型及危害程度,对园林植物病害的防治及深入研究具有较强的指导和借鉴作用。     

Landscape pattern and spatial variability of leaf area index in Eastern Amazonia

Uncertainties about the implications of land-cover heterogeneity on the Amazonian carbon (C) and water cycles are, in part, related to the lack of information about spatial patterns of key variables that control these fluxes at the regional scale. Leaf area index (LAI) is one of these key variables, regulating a number of ecosystem processes (e.g. evaporation, transpiration and photosynthesis). In order to generate a sampling strategy for LAI across a section of Amazonia, we generated a landscape unit (LU) map for the Tapajós region, Eastern Amazonia, as a basis for stratification. We identified seven primary forest classes, stratified according to vegetation and/or terrain characteristics, and one secondary forest class, covering 80% of the region. Primary forest units were the most representative, covering 62% of the total area. The LAI measurements were carried out in 13 selected LUs. In each LU, we marked out three 50 m × 50 m plots giving a total number of 39 plots (9.75 ha). A pair of LAI-2000 plant canopy analysers was used to estimate LAI. We recorded a total of 25 LAI measurements within each plot. We used the field data to verify the statistical distribution of LAI samples, analyse the LAI variability within and among sites, and show the influence of sample size on LAI variation and precision. The LAI showed a high coefficient of variation at the plot level (0.25 ha), from 5.2% to 23%, but this was reduced at the landscape unit level (three co-located plots, 1.8–12%). The level of precision was <10% and 15% at the plot and landscape unit level, respectively. The LAI decreased from a dense lowland forest site (5.10) to a secondary forest (3.46) and to a pasture site (1.56). We found evidence for differences in the scale of spatial heterogeneity of closed canopy forest versus open canopy forest and palm forests. Landscape variables could, in part, explain differences in LAI among forest sites, and land use is an important modifier of LAI patterns. The stratified LAI sampling proposed in the present study could cope with three important aspects of C and water fluxes modelling: (1) optimise the information obtained from field measurements, which is an advance for models parameterisation, compared to the usual random sampling; (2) generate information for a subsequent scaling up of point field measurements to surfaces covering the whole region; and (3) build a useful basis for validation of estimations, based on remote sensing data, of LAI in the Tapajós region. The variability of LAI in the Tapajós region showed that this variable is a source of uncertainty for large-scale process modelling.     

The effects of different types of management,functions, and characteristics of stands in Polish forests on the amount of coarse woody debris

In the modern forestry paradigm, many factors influence the amount of coarse woody debris (CWD). The present paper analyzes the effects of both local (national) programs (special functions of forests) and European programs (Natura 2000 sites), as well as the individual characteristics of forest stands. The study was conducted on 2,752 sampling plots distributed over an area of about 17,500 ha and located in lowland stands having a species composition typical of large areas in central Europe. Natura 2000 areas contained significantly more CWD (8.4 m³/ha) than areas not covered by the program (4.8 m³/ha). However, this is due to the fact that Natura 2000 sites involve well-preserved forest areas, such as nature reserves (26.6 m³/ha). In the managed forests that have been covered by the Natura 2000 program over the past several years, the volume of CWD has not increased. Forests with ecological and social functions differed slightly in the amount of CWD. More CWD occurred in protected animal areas (8.7 m³/ha) than in stands damaged by industry (3.9 m³/ha). Intermediate CWD levels were found in water-protection forests and in forests located around cities and military facilities. In managed forests, the lowest CWD volume was observed in middle-aged stands. The species composition of the stand had little effect on the volume of CWD. Only stands with a predominance of ash and alder had higher CWD levels (13.5 m³/ha). More CWD was found in stands whose species composition did not represent the potential site quality (6.4 m³/ha) than in habitats with the optimum species composition (3.8 m³/ha). CWD volume should be systematically increased taking into consideration local natural conditions. Such efforts should be focused on particularly valuable regions, and especially on Natura 2000 sites, where the threshold values reported from other European forests should be reached. Leaving some trees to die naturally and retaining reasonable amounts of such trees ought to be incorporated into CWD management practice in Poland.