Effects of permethrin sprays on the mite fauna of apple orchards

In two apple orchard trials, single high volume sprays of 25–50 mg permethrin/ litre greatly reduced numbers of the phytosend predatory mite Typhlodromus pyri whether the spray was timed pre-bloom at growth stages from ‘bud-burst’ to ‘late green cluster’ or post-bloom in June. At ‘bud-burst’T. pyri were partially protected in hibernating sites on the bark, but the lethal effect of the spray was only delayed; no appreciable selectivity could be obtained by this early timing. Bioassays showed that the persistent toxicity of permethrin residues on bark or on leaves declined to a low level within 20 days, and was related to the decline in residue levels determined by G.C. analyses. Residues were detectable for 3 months or longer. Resurgence of spider mites, Panonychus ulmi, occurred within 2 months after all spray timings, and effective predation by T. pyri was only fully re-establised after several months. In one trial, apple rust mite, Aculus schlechtendali also increased when T. pyri was reduced by spraying. Tydeid mites were killed by permethrin.     

Simulation model of the European red mite andTyphlodromus pyri in New Zealand apple orchards

A deterministic model of the European red mitePanonychus ulmi (Koch) and its predatorTyphlodromus pyri Scheuten is presented. The model is driven by daily maximum and minimum temperatures, and requires the per-leaf densities of both mites in spring to start each simulation. It was successful at predicting the general change in mite populations, and the peak prey density, but deviations from field results occurred at low prey density. Simulations have suggested that the present miticide spray thresholds used in New Zealand are too conservative and have also provided further insight into integrated control ofP. ulmi.     

The impact of insecticides applied in apple orchards on the predatory mite Kampimodromus aberrans (Acari: Phytoseiidae)

Kampimodromus aberrans is an effective predatory mite in fruit orchards. The side-effects of insecticides on this species have been little studied. Field and laboratory experiments were conducted to evaluate the effects of insecticides on K. aberrans. Field experiments showed the detrimental effects of etofenprox, tau-fluvalinate and spinosad on predatory mites. Spider mite (Panonychus ulmi) populations reached higher densities on plots treated with etofenprox and tau-fluvalinate than in the other treatments. Single or multiple applications of neonicotinoids caused no detrimental effects on predatory mites. In the laboratory, spinosad and tau-fluvalinate caused 100 % mortality. Etofenprox caused a significant mortality and reduced fecundity. The remaining insecticides did not affect female survival except for imidacloprid. Thiamethoxam, clothianidin, thiacloprid, chlorpyrifos, lufenuron and methoxyfenozide were associated with a significant reduction in fecundity. No effect on fecundity was found for indoxacarb or acetamiprid. Escape rate of K. aberrans in laboratory was relatively high for etofenprox and spinosad, and to a lesser extent thiacloprid. The use of etofenprox, tau-fluvalinate and spinosad was detrimental for K. aberrans and the first two insecticides induced spider mite population increases. The remaining insecticides caused no negative effects on predatory mites in field trials. Some of them (reduced fecundity and repellence) should be considered with caution in integrated pest management programs.     

The effect of groundcover and herbicide treatment on twospotted spider mite density and dispersal in southern Oregon pear orchards

A total of 49 groundcover plant species representing 47 genera in 22 families were identified from a survey of 5 pear orchards. Density of twospotted spider mite (Tetranychus urticae Koch) inhabiting these plants was estimated visually several times during the field season. Plants were ranked in 1 of 3 categories depending on mite densities found on these plants during the summer. T. urticae was found to be highly abundant (category 3) on 26 species, at lower densities on 10 species (category 2), and was rarely or never found on the remaining 12 species (category 1). Dispersal of mites from groundcover plants into trees was found to be highly variable within and between orchards. Within orchard dispersal appeared to be related to the distribution and abundance of category 3 host plants in the orchard. Variability between orchards may also be affected by groundcover management techniques and levels of acaricide resistance in T. urticae. The use of herbicides to control groundcover plants significantly increased the dispersal of T. urticae into the orchard trees.     

Oviposition model of overwintered adult Tetranychus urticae (Acari: Tetranychidae) and mite phenology on the ground cover in apple orchards

The phenology of overwintered Tetranychus urticae was studied on the ground cover in apple orchards in the early season, and an oviposition model of overwintered adults was developed. The movement of overwintered adults from trees to ground cover started from mid-March and continued until mid-April. One life cycle from eggs to new adults (the 1st generation adults) on the ground cover was from late March to early May. The longevity and fecundity of overwintered T. urticae were affected largely by temperature. The longevity ranged from 46.6 days at 10 degrees C to 6.5 days at 35 degrees C. The total fecundity was minimum (0.2 eggs) at 10 degrees C and maximum (45.5 eggs) at 25 degrees C. The relationship between total fecundity and temperature was described well by a nonlinear equation. The cumulative age-specific oviposition rate was described well by the two-parameter Weibull function. The overall adult survival exhibited a reverse logistic curve. Three temperature-dependent components, age-specific cumulative oviposition rate, temperature-dependent total fecundity and age-specific survival rate functions, were incorporated into an oviposition model. The oviposition model simulation described the occurrence pattern of eggs laid by overwintered T. urticae on the ground cover in apple orchards relatively well.     

Impact of the predatory mite Anystis baccarum (Prostigmata: Anystidae) on apple rust mite Aculus schlechtendali (Prostigmata: Eriophyidae) populations in Northern Ireland Bramley orchards

Anystis baccarum is a common predatory mite in Northern Ireland Bramley orchards. To determine its effect on Aculus schlechtendali populations, sticky traps and sprays of demeton‐S‐methyl were used to exclude A. baccarum from branches. Out of four trials, exclusion of A. baccarum by sticky traps alone resulted in significantly greater numbers of A. schlechtendali in one trial. In the other trials where A. schlechtendali numbers were lower, there was either no effect, or possible evidence of fewer A. schlechtendali. The combination of demeton‐S‐methyl treatments and sticky traps to exclude A. baccarum resulted in significantly more A. schlechtendali in two trials out of three in 1998. It seems likely that this resulted from the dual effects of stimulation of A. schlechtendali reproduction by the acaricide and the absence of predation by A. baccarum, because acaricide treatment alone in 1999 resulted in significant reductions in A. schlechtendali numbers at the end of the season. This effect could have resulted from A. baccarum re‐invading the treatment branches after the effects of the acaricide had worn off. It is recommended that growers are encouraged to conserve A. baccarum within their orchards.     

印度小裂绵蚜在土壤中的垂直分布及其种群消长

【目的】印度小裂绵蚜Schizoneurella indica Hille Ris Lambers是在云南昭通苹果上发现的一种新害虫,发生普遍且严重。研究印度小裂绵蚜种群在土壤中的垂直分布及其消长动态是为了掌握其发生与危害特点。【方法】2002—2006年,我们采用盆栽和田间调查的方法对印度小裂绵蚜在土壤中的垂直分布和种群消长开展了研究。【结果】印度小裂绵蚜田间种群数量高峰期主要集中发生在9—12月,5—7月份为其田间种群快速增长期,种群增长率可达200%~273%。印度小裂绵蚜无翅蚜种群在0~30 cm的土壤范围内占总虫量的49.0%,30~60 cm的占27.0%,>60 cm的占24.0%。无翅蚜的各虫龄全年均有发生,冬季以第4龄若虫和无翅成虫为主。有翅蚜的发生全年只有1个时期,为11月上旬至12月下旬。【结论】印度小裂绵蚜田间种群数量全年发生1个高峰期,主要集中在0~30 cm的土壤范围内,随着土壤深度的增加,印度小裂绵蚜种群数量亦逐渐下降。田间有翅蚜虫量极少,较难观察到。     

Population dynamics of Cacopsylla melanoneura (Hemiptera: Psyllidae) in northeast Italy and its role in the apple proliferation epidemiology in apple orchards

In the current study, incidence of 'Candidatus Phytoplasma mali' in an experimental apple orchard in northeast Italy, in addition to abundance and phytoplasma infectivity of Cacopsylla melanoneura (F?rster) (Hemiptera: Psyllidae) was determined and the role of this psyllid as a vector of 'Ca. P. mali' in this region was reviewed. Insect samples collected in the orchard by the beating method indicated high abundance of C. melanoneura (up to 7.92 specimens/branch); however, the psyllid C. picta was not observed. Molecular analyses revealed presence of 'Ca. P. mali' in 6.25% of overwintered psyllids. This infection rate is quite high in comparison to other localities where C. melanoneura is known as the main vector of the phytoplasma. This finding supports the assumption that C. melanoneura also is paramount in the epidemiology of the apple proliferation disease also in northeast Italy. Moreover, we correlated immigration dynamics to the temperatures registered in the apple orchard, and defined an immigration index to predict the progressive arrival of the overwintered adults from winter sites. Psyllids start to reach the apple orchards when either the average of the maximum temperature of the 7 d is above 9.5 degrees C or the immigration index has a positive value. This index will be a useful tool for the growers to prevent apple proliferation phytoplasma spread with well-timed insecticide treatments targeted against C. melanoneura. However, further research is needed to validate or adjust the index to other apple growing regions, which may affect more efficacious management of this disease and psyllid vector.     

Effect of anti‐hail nets on Cydia pomonella behavior in apple orchards

Over the last 10 years, the use of nets to protect pome fruit from hailstorms has increased. In this study, we investigated the effect of these nets on the behavior of the codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), a major pest of apple, Malus domestica Borkh. (Rosaceae). Experiments were carried out in net‐covered and uncovered apple orchards treated with conventional insecticides. The number of codling moth males caught in pheromone‐ and virgin female‐baited traps was significantly reduced in net‐covered compared to uncovered plots. In addition, inhibition of mating by the net was demonstrated by significant reductions in mating of tethered virgin females. Fruit injury was consistently lower in net‐covered plots vs. uncovered plots. Because of the reductions in male trap catch, the reduced female mating frequency, and the lower level of damage, we conclude that flat anti‐hail nets have a disruptive effect on the reproductive behavior of the codling moth.     

红富士苹果园酵母多样性研究

从北京顺义和山东泰安红富士苹果园采集果实、叶片、树皮和土壤等不同基物,分离酵母菌,利用26S rDNA的D1/D2区域序列分析并结合形态学特征和SSCP分析对这些菌株进行了分类学研究,探讨了苹果园酵母的物种多样性及其分布。北京苹果园共分离酵母菌129株,鉴定为13属21种,优势属为Pichia（4个种）,Cryptococcus（3个种）,Pseudozyma（3个种）,子囊菌占较大优势,分布于8属12种,占总种数的57.1%。山东苹果园共分离酵母291株,鉴定为13属26种,优势属为假丝酵母Candida（6个种）,毕赤酵母Pichia（4个种）和隐球酵母Cryptococcus（3个种）,并且子囊菌占较大优势,分布于7属17种,占总种数的65.4%。     

Empirical models of the conductance of leaves in apple orchards

Abstract. Seasonal data on leaf conductance (g_l) for three different apple cultivars grown in four separate orchards with different aged trees was studied between 1979 and 1985. A number of empirical models for predicting leaf conductance from environmental measurements were compared using this data and a general method for adapting such models for the prediction of different data sets is proposed. Although stepwise multiple regression identified relative humidity or vapour pressure as important variables, it frequently did not identify the optimal set of independent variables, which often did not include either of these. There was no advantage in regressing g_l against principal components of the environment, rather than against the raw environmental variables. A simple model involving air vapour pressure deficit, air temperature and a hyperbolic function of irradiance was found to explain between 32 and 62% of the variance in g_l for the different data sets. Parameters fitted for one data set led to the effective prediction of g_l in other years or plots. The model fit could generally be improved significantly by including soil moisture deficit among the independent variables.     

Effect of plant architecture and hail nets on temperature of codling moth habitats in apple orchards

Plant architecture of apple trees in commercial orchards was rapidly changed from traditional tall trees to dwarf trees to optimize yield and fruit quality. Additionally, hail nets are widely used to prevent yield loss by hail. These changes are expected to considerably influence the orchard microclimate and thus the developmental rates of pest insects in apple. However, these relationships have not yet been fully elucidated. The present study was conducted over the seasonal cycle to investigate the influence of plant architecture and hail nets on the habitat temperatures of the codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), in apple, Malus domestica Borkh. (Rosaceae). Within the canopies, leaf area index (LAI) and global site factor (GSF) were quantified using hemispherical photography. Temperature was analysed for the main habitats of the different codling moth stages, i.e., air within the canopy, bark of tree stems, and apple fruit. In dwarf trees, LAI was lower, leading to a higher GSF than in tall trees. Hail nets did not influence LAI and GSF. Results for dwarf trees compare as follows with those for tall trees: Average air temperatures within the canopy were 0.7 °C higher during daytime, whereas 0.4 °C lower at night. Mean surface temperatures of bark were 0.9 °C higher on sunny and 0.4 °C on overcast days. Mean surface temperatures of apple fruits were 1.8–2.7 °C higher on sunny days, but 0.6 °C cooler on overcast days. The effect of hail nets was confined to a reduction of the air temperature within the canopy by approximately 0.2–0.8 °C. Bark and apple surface temperatures were not significantly affected. Based on the temperature differences in the habitats considered, the calculated development of the codling moth in dwarf trees was on average 3 days faster than in tall trees. The calculations imply a negligible effect of hail nets on codling moth development.     

Fireblight epidemic among Kentish apple orchards in 1969

Evidence from field observations and orchard plans indicates that the fireblight epidemic among apples in 1969 followed a critical combination of weather conditions. There is little doubt that diseased hawthorns, situated entirely or mainly to the north-west of the main lanes of infection, were the source of inoculum. Initial infection was confined to shoots. No blossom infection was seen at any time. Weather data from a nearby meteorological station point to distribution of inoculum having taken place on one of the days 6–10 July when strong winds, rainfall and hailstorms occurred. These days were followed immediately by temperatures above 18d?C which are considered suitable for infection and for progress of the bacterium within the shoot tissues. The control measures advised were the removal and destruction of diseased parts, the disinfection of pruning implements, the protection of wounded surfaces against infection and the destruction of nearby diseased hawthorns.     

Washing technique for monitoring mites in apple orchards

A shake-and-wash technique for monitoring the predatory phytoseiid mitesTyphlodromus pyri, Amblyseius finlandicus, and their prey,Panonychus ulmi, Tetranychus urticae andAculus schlechtendali in commercial apple orchards was developed. The removal and recovery of mites from leaves, shoots and spurs is based on agitating the plant material by hand in alcohol and subsequently removing the mites using a separating funnel. The mites are quickly killed and easily washed off the plant material, and are thus well preserved for further study. The technique is more efficient than directly counting the mites on plant material under a dissection microscope and can be easily employed both in the laboratory and in the field.     

Effect of native natural enemies on the population dynamics of the grape mealybug,Pseudococcus maritimus (Hom.: Pseudococcidae), in apple and pear orchards

The impact of native natural enemies on populations of the grape mealybug,Pseudococcus maritimus (Ehrhorn) in apple and pear orchards was assessed using a combination of techniques, including exclusion cages, limb-banding, and visual inspection of shoots and fruits. The complex of native natural enemies (which included two encyrtid parasitoids, (Pseudaphycus websteri Timberlake andMayridia species), a coccinellid beetle (Hyperaspis lateralis Mulsant), and a chamaemyiid fly (Leucopis verticalis Malloch), provided reasonably good control in orchards that had not been treated with insecticides for one to two years. However, surveys indicated that most of these species were absent from orchards regularly sprayed with pesticides.     

苹果蠹蛾成虫在苹果园中的动态分布

为了解苹果蠹蛾Cydia pomonella(L.)在田间的空间分布格局及其季节变化,从而为基于不同果园特点的诱捕器监测及有害生物综合治理提供基础信息,2005及2010年,本研究选择甘肃高台县和张掖甘州区的两处果园,应用地统计方法对其中的成虫空间分布及其季节性变化进行了研究。其结果显示:在采取常规防治的果园中,苹果蠹蛾发生热点集中在果园的边缘,且随着成虫数量季节性的消长,这种边界效应变的更加突出;而在采取了迷向防治措施的果园当中,诱捕器捕获量的空间相关性与信息素浓度和虫口数量有密切的关系。根据以上研究结果,在今后的监测工作中,尤其是在较大的果园中进行诱捕器布局的时候,应将果园的边缘地区作为重点监测区域。     

植草带宽度对蜘蛛和步甲群落动态及比邻玉米田害虫发生的影响

农田边界植草带是农田系统各斑块间生物物种迁移和群落演替、物质和能量交换的主要区域,对维持农业生物多样性及提高农田生产力具有重要意义。基于作物-害虫-天敌互作有机整体对植草带宽度的响应,选取不同宽度植草带(2 m、4 m、6 m)及其比邻农田并以对应宽度作物边界作为对照,采用地表陷阱法对蜘蛛和步甲进行取样调查,探究植草带宽度对蜘蛛和步甲种群结构、迁移扩散规律以及对农田害虫控制潜力的影响。结果表明:植草带内蜘蛛和步甲个体数均显著高于对照条带,4 m、6 m植草带的蜘蛛和步甲多度显著高于2 m植草带,且物种丰富度和多度显著高于其对照条带。此外,不同宽度植草带蜘蛛和步甲群落存在较高的异质性,蜘蛛和步甲群落结构差异显著;在4 m和6 m植草带及其比邻玉米田内,蜘蛛和步甲多度在植草带和植草带与比邻玉米田交界处显著高于农田内部,且随距离的增加,蜘蛛物种多度呈显著降低趋势,植草带宽度和距离共同决定蜘蛛和步甲的空间分布;Monte Carlo检验结果表明,植草带宽度、植被Margalef指数对农田中蜘蛛和步甲群落结构的影响均达到显著水平,蜘蛛主要优势科和步甲主要优势种主要分布在6 m植草带比邻玉米田内;4 m、6 m植草带比邻的玉米田中蜘蛛和步甲对玉米害虫的益害比显著高于2 m植草带比邻的玉米田,且4 m、6 m植草带显著增加了玉米籽粒的百粒重及比邻农田的玉米总产量。本研究对植草带涵养捕食性天敌预防害虫发生的最适宽度进行探索,综合考虑植草带耕地占用、天敌涵养和生物控害潜力等因素,确定4 m宽度植草带是具有推广价值的农田边界模式。