The effects of windbreaks on the blossom-visiting fauna of apple orchards and on yield

Windbreaks of coir netting were erected in apple orchards during the flowering period in 1969 and 1970 in an attempt to increase the number of insect pollinators present. Suction traps were used to sample flying insects; insects visiting trees were sampled by examination of flowers. The sheltered zone behind the windbreaks contained more of most species of insects than elsewhere. Increases in final fruit set of approximately 30% in 1969 (cv. Cox's Orange Pippin) and 20 % in 1970 (cv. White Jersey) occurred in trees receiving maximum shelter, and these were due mainly to the increased abundance, and possibly increased activity, of honey bees there. Fruit size was not reduced where yields were increased.     

The permeability of artificial windbreaks and the distribution of flying insects in the leeward sheltered zone

The number of flying insects in the sheltered zone to leeward of artificial windbreaks of 0, 25, 45 and 70% permeability was greater than in unsheltered areas. Insects accumulated in the air nearer to dense windbreaks than to more permeable ones, and the position of maximum aerial density of insects coincided with that of maximum shelter. The more dense the windbreak the greater the numbers in the air to leeward. Absolute wind speed slightly affected the position of maximum aerial density behind a 45% permeable fence.     

Methode zum Nachweis der Dauersporen des Kohlhernieerregers Plasmodiophora brassicae in gärtnerischen Kultursubstraten

Populations of pathogenic Pseudomonas syringae pv. syringae were monitored on apparently healthy leaves, blossoms, and fruit from two apple orchards with known histories of blister bark and a pear orchard with a known history of blossom blast. Populations on blossoms and fruits were higher on pears than on apples. Yellow-pigmented, non-pathogenic bacteria might have suppressed or masked the presence of P. syringae pv. syringae on apple trees. Populations of P. syringae pv. syringae on apple and pear leaves fluctuated sharply but higher levels generally occurred during the 1984/85 growing season than during the drier 1983/84 season. This investigation indicates that the resident phase of P. syringae pv. syringae is probably a major source of inoculum for apple blister bark and pear blossom blast in South Africa.     

Tethered flight activity of pear psylla, Cacopsylla pyricola: Seasonal, host, and morphotypic effects

Pear psylla, Cacopsylla pyricola Förster (Homoptera: Psyllidae), was flown in the laboratory to test hypotheses suggested by field observations. Flight durations of the same insects flown on two different days were highly correlated, suggesting that there were biolgical differences among insects in flight tendencies. Flight durations were similar between summerform and winterform morphotypes. Flight frequencies and durations increased between September and November collections of winterforms, results that are consistent with field observations. Long-duration (60+ min) flights were three to four times as frequent in winterforms restricted to senescing pear foliage compared to insects provided access to pear seedlings. Winterforms collected during the fall flight period from a pear orchard and an adjacent apple orchard (an overwintering habitat) showed similar flight durations. There was no correlation between flight durations and any of five body and wing measurements; body size of winterforms increased between September and November. It has been proposed elsewhere that much of the fall movement into adjacent non-pear habitats by winterforms is due to short duration non-migratory flights rather than to a true migratory flight. The lack of differences between apple- and pear-collected winterforms may be consistent with this hypothesis.     

Identification of Pyrus Single Nucleotide Polymorphisms (SNPs) and Evaluation for Genetic Mapping in European Pear and Interspecific Pyrus Hybrids

We have used new generation sequencing (NGS) technologies to identify single nucleotide polymorphism (SNP) markers from three European pear (Pyrus communis L.) cultivars and subsequently developed a subset of 1096 pear SNPs into high throughput markers by combining them with the set of 7692 apple SNPs on the IRSC apple Infinium® II 8K array. We then evaluated this apple and pear Infinium® II 9K SNP array for large-scale genotyping in pear across several species, using both pear and apple SNPs. The segregating populations employed for array validation included a segregating population of European pear (‘Old Home’בLouise Bon Jersey’) and four interspecific breeding families derived from Asian (P. pyrifolia Nakai and P. bretschneideri Rehd.) and European pear pedigrees. In total, we mapped 857 polymorphic pear markers to construct the first SNP-based genetic maps for pear, comprising 78% of the total pear SNPs included in the array. In addition, 1031 SNP markers derived from apple (13% of the total apple SNPs included in the array) were polymorphic and were mapped in one or more of the pear populations. These results are the first to demonstrate SNP transferability across the genera Malus and Pyrus. Our construction of high density SNP-based and gene-based genetic maps in pear represents an important step towards the identification of chromosomal regions associated with a range of horticultural characters, such as pest and disease resistance, orchard yield and fruit quality.     

The horizontal and vertical distribution of flying insects near artificial windbreaks

Lath fences 3 ft and 8 ft high affected the horizontal distribution of flying insects similarly: most insects accumulated at a distance equal to 2–3 times the height of each fence to leeward, where catches, measured at 14 and 38 in. (≡ to 0·4 times the height of the fence above the ground) were 30–40 % greater than in exposed positions. Behind an 8 ft fence accumulations extended vertically to 12–16 ft (≡ to 1·5-2·0 times the height of the fence). Vertical profiles of weak-flying insects, in winds > 3 m.p.h. differed in sheltered and exposed positions; in shelter the boundary layer was deeper and insects were more abundant nearer the ground than elsewhere. For strong flyers, and insects which flew only in winds < 2 m.p.h., vertical profiles in sheltered and exposed positions were indistinguishable.     

Flowers for better pest control? The effects of apple orchard ground cover management on green apple aphids (Aphis spp.) (Hemiptera: Aphididae), their predators and the canopy insect community

Effects of habitat diversification through ground cover management on green apple aphids (Aphis spp.) (Hemiptera: Aphididae), woolly apple aphid (Eriosoma lanigerum [Haussmann]) (Hemiptera: Aphididae), their insect natural enemies and the most abundant canopy insects (in the Neuroptera, Fulgoromorpha, Cicadomorpha, Heteroptera, Coleoptera and Formicidae) were studied in an apple orchard over 6 years. The composition and diversity of the main functional groups of canopy insects was also compared. Habitat diversification was achieved by changing ground cover conditions within the orchard. In the treatment termed FLOWER, annual and/or perennial flowering plants were sown in the alleys of an apple orchard. Other ground cover treatments were weed-free bare ground (termed BAREgr) and orchard plots with alleys of mowed grass (termed GRASS), which served as control treatments. We found no evidence that habitat diversification enhanced the biological control of green apple aphids compared to the control treatments. However, the greater plant cover in FLOWER resulted in increased woolly apple aphid infestations compared to BAREgr or GRASS. The abundance of various beneficial or neutral canopy insects – Chrysoperla carnea sensu lato (Neuroptera, Chrysopidae) adults, leafhoppers and treehoppers, planthoppers, herbivorous (non-apple feeding) beetles, dipterans and parasitoid wasps – also increased in FLOWER as compared to BAREgr, with GRASS being intermediate between the other treatments. Significantly greater species richness and diversity was found in FLOWER than in BAREgr for most of the functional groups sampled, although the number of predacious insect species was similar among treatments. The composition of the studied functional groups showed high similarity in FLOWER and GRASS, but these treatments were different from BAREgr. Effects of groundcover management on the dominant insect species are discussed.     

Species composition of leaf beetle assemblages in the canopies of apple and pear orchards in Hungary and Great Britain (Coleoptera: Chrysomelidae)

The species richness and species composition of Coleoptera assemblages were investigated in the canopies of apple and pear orchards in Hungary and in the apple orchards in Great Britain. The investigations were carried out in Hungary (Nagykovácsi: 3 plots, Kecskemét: 5 plots, Sárospatak: 4 plots) between 1990-94, and in Great Britain in Kent (East Malling, Marden and Robertsbridge) in 2001 and 2002. Former investigations in Hungary revealed that the diversity of Coleoptera assemblages in the canopy of apple and pear orchard were surprisingly high. As a result of our investigations it was found that altogether 324 species, almost 3% of the Hungarian beetle fauna were represented: 253 species in apple orchards and 188 species in pear orchards. Similar results were obtained in the investigations carried out in Great Britain between 2001-2002. In Hungary, the majority of the species belonged to the families Curculionidae, Chrysomelidae and Coccinelidae. The proportion of leaf beetles varied between 15 and 20%. The most common leaf beetle species in the canopy of the commercial orchards were Phyllotreta vittula, Phyllotreta atra, Phyllotreta nigripes, Oulemta melanopus, and Aphthona euphorbiae. In the abandoned orchards the most common species were Luperus xanthopoda, Smaragdina salicina and Orsodacne liieola. In Great Britain 44 leaf beetle species were found in the canopies of the investigated orchards. The species with higher abundance were Aphthona euphorbiae. Chaetocnema concinna and Longitarsus parvulus. We concluded, that leaf beetles give high part of the orchard canopy biodiversity and sometimes occur with high species richness and abundance. However, the reasons of their occurrence and their potential role are poorly known.     

Comparison of pome fruit orchard inhabiting spider assemblages at different geographical scales

1 The composition of pome fruit orchard inhabiting spider assemblages was investigated at different geographical scales (Holarctic, European, inter- and intraregional levels within Hungary) using previous faunistic studies and data collected in Hungary between 1995 and 1997. Samples in Hungary were taken from the canopy and herb layer of apple and pear orchards in five markedly different fruit-growing regions by beating and sweep-netting methods. 2 The composition of canopy spider assemblages of apple orchards was analysed for the Holartic region and found to be determined by latitude at family level, and by the main zoogoegraphical regions at genus level. At the European scale, both the genus and species composition changed along a north–south gradient. 3 A comparison among apple and pear orchards located in different regions in Hungary, showed that both foliage- and grass-dwelling spider assemblages varied considerably in species composition and dominance order. 4 Within the same region, both the foliage- and grass-dwelling spider assemblages showed moderate differences in apple and pear orchards submitted to different treatments. Although the assemblages of spiders inhabiting the canopy and the herbaceous layer can be unambiguously distinguished, some overlap still occurs. 5 We conclude that the composition of spider assemblages is basically determined by geographical location. Although both pesticide treatments and available prey densities can influence the population of spiders, such factors are of moderate importance when compared with the effect of regionality, even when considered at smaller scale. However, most members of the family Theridiidae and the large orb-weavers (Araneidae) decreased considerably in treated plots. Scale-specific differences are thus relevant in determining the composition of prey–predator systems in orchards, and should be taken into account when designing integrated pest management (IPM) programs for apple and pear orchards.     

Recommendations on minimum experimental plot size and succession of aphidophaga in West Virginia, USA, apple orchards

Five apple orchards in West Virginia, USA, were managed with five different pest management practices ranging from unsprayed to conventional insecticides. Data were collected on aphid, predaceous insect, and spider abundance every 2 weeks from May to July along one or two randomly selected, 15 consecutive tree transects. A total of 892 individual predaceous insects was observed: 32% wereAphidoletes aphidimyza, 21% wereCoccinella septempunctata and the rest were from 13 other taxa. The most important aphid predator seemed to beC. septempunctata. Of the 32 sample transects with predators, 72 % showed an edge effect in which either the standard error or mean of predator abundance differed from the edge towards the center of the orchard. This edge effect extended a mean of 7 trees (30 m) into the orchard. Only 39% of the 33 transects that had spiders showed an edge effect, extending into the orchard a mean of 8 trees (33 m). However, 75% of the transects with more than one spider per tree had an edge effect of 10 trees (43 m). We recommend a minimum border of seven trees before sampling for aphid predators and 10 trees before sampling for spiders. A recommended experimental plot size, for semi-dwarf, free-standing apple orchards, to eliminate edge effects is 1.25 ha for aphidophaga, 1.5 ha for spiders; a minimum plot size of 0.6 ha for aphidophaga and 0.75 ha for spiders would minimize edge effects.     

Cross-correlation analysis of fluctuations in local populations of pear psyllids and anthocorid bugs

1. To test whether predatory anthocorids migrate into pear orchards when populations of pear psyllids are building up, a cross-correlation analysis was carried out on their population numbers. Predator and prey population sizes were assessed weekly in 3 consecutive years (1991–93) by sampling pear leaves for eggs and nymphs of psyllids and pear tree branches for adult psyllids, as well as adults and nymphs of predatory anthocorids. The time-series consisted of numbers (per leaf or branch) averaged over preselected pear trees in an orchard and, in addition, over other trees selected along the hedgerows flanking the orchard. 2. The fluctuations in populations of adult and juvenile anthocorids showed strong cross-correlations with those of the eggs and nymphs of pear psyllids, but less correlation with adults of pear psyllids, as expected based on their increased ability to escape from predation. The psyllids always appeared first on the pear trees, resulting in positive phase shifts. The first peak of adult anthocorids on pear trees was always later than the first peak in the hedgerows, and the first peak of nymphal anthocorids on pear trees was always later than the first peak of adults on these pear trees. In each of the 3 years, anthocorids were rarely observed in the pear orchard during the first part of the growing season (April–June), but during the second half of the growing season (July–August) there was a strong numerical response of the anthocorid populations to increasing population densities of pear psyllids. 3. These results provide support for the hypothesis that the numerical response of the predators to prey density is caused initially by migration of anthocorids into the pear orchard and then by a reproductive response. The migrants originate from the hedgerows and other trees elsewhere, where they feed on aphids during the first part of the growing season.     

Impact of trap architecture, adjacent habitats, abiotic factors, and host plant phenology on captures of plum curculio (Coleoptera: Curculionidae) adults

Pyramid traps, 2.44 m and 3.66 m in height, were compared with standard-sized pyramid traps, 1.22 m in height, to assess the impact of trap architecture on captures of adult plum curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), in two apple (Malus spp.) orchards and a blueberry (Vaccinium spp.) planting. The effects of adjacent habitat (organic orchard versus wooded areas), abiotic factors, and phenological stages of apple also were assessed to determine whether these variables influenced trap captures. Standard-sized pyramidal traps captured significantly more adults than larger trap variants. In the apple orchards, most adults (70-80%) were captured before petal fall with the exception of blocks adjacent to the organic orchard (25%). Significantly more adults were captured along the edge of an apple orchard (managed using an integrated pest management strategy) facing an organic apple orchard (76%) than along the edge facing wooded areas (24%). There was a significant positive correlation between daily trap captures and mean daily temperatures before petal fall in apple orchards.     

Acylcyclohexanediones and biological control agents: combining complementary modes of action to control fire blight

Acylcyclohexanediones and antagonistic bacteria sprayed alone or in combination have been shown to suppress fire blight of apple and pear. Acylcyclohexanediones, such as prohexadione-calcium and trinexapac-ethyl, increase plant resistance and are effective against the shoot blight phase of the disease. Antagonistic bacteria, such as Pantoea agglomerans, compete with the pathogen (Erwinia amylovora) for space and nutrients on stigmas, which prevents blossom blight. Potential synergistic effects of acylcyclohexanediones with P. agglomerans for fire blight suppression were investigated on leaves and flowers of apple and pear. Acylcyclohexanediones modified the composition of apple nectar and stigmatic secretions, which resulted in moderately higher epiphytic populations of P. agglomerans strain P10c. In experiments in apple orchards, the combination of acylcyclohexanediones and P. agglomerans gave the greatest protection against blossom blight and shoot blight. In pear orchards, under natural infection conditions, a similar result was obtained for the 3 of the 4 years of the experiment.     

梨花中熊果苷的高效液相色谱分析

采用高效液相色谱法对不同时期、不同品种的梨花中熊果苷的含量进行了分析,色谱柱为Hypersil BDSC18(4.6 mm×250 mm,5μm),流动相为甲醇∶水(6∶94),加入甲酸0.05%,检测波长280 nm。结果表明:熊果苷在0.01～5.00μg范围内线性关系良好(r=0.9999),平均加标回收率为97.7%。不同生长期的鸭梨梨花中熊果苷的含量一般在10 mg/g以上,尤以花芽萌动期时含量最高,达到35.7 mg/g(鲜重计)。不同品种的9份梨花样品中,熊果苷含量在3.5～10.5 mg/g之间。     

不同栽培管理梨园梨小食心虫发生程度研究

梨小食心虫Grapholitha molesta(Busck)是梨园中的一种重要害虫。本论文采用性诱剂诱集法研究了不同栽培管理条件下梨园梨小食心虫发生的情况。结果表明,在5种不同种植模式的果园中,梨小食心虫在单植桃园中发生最重,试验期间梨小食心虫的日平均诱蛾量为10.9头/盆,与其他4种栽植模式果园的诱捕量均呈显著差异,且混有桃树的果园中梨小食心虫的发生数量多,而单植梨园、梨苹果混栽园、单植苹果园的梨小食心虫发生相对较轻。果实套袋的管理方法也可以显著降低梨小食心虫的发生数量,非套袋梨园的日平均诱捕量为13.8头/盆,是套袋梨园的1.52倍。试验还表明,不同品种和不同树龄的梨树对梨小食心虫的抗虫性均存在显著差异。酥梨比巴梨的抗虫性差,试验期间酥梨园的日平均诱捕量为12.6头/盆,是巴梨园的2.21倍,而40年老酥梨园日平均诱蛾量为12.5头/盆,是20年酥梨园诱蛾量的2.5倍。     

Population dynamics of the citrus red mite, Panonychus citri (McGregor) (Acari: Tetranychidae) in Japanese pear orchards

In spring a population of the citrus red mite (Panonychus citri),a non-diapausing species, migrated to a Japanese pear orchard, mainly from nearby Japanese holly trees, but in autumn most of the mites starved to death while the rest returned to the holly trees. In the Japanese holly trees, the population of mites reached their maximum density in late May1993 and in mid-June 1994 on overwintered leaves and moved to newly opened leaves in mid-June 1993 and late June 1994. The mites tended to disperse abruptly in early June or mid-June and again towards the end of June. The mites inhabiting the holly trees appeared to migrate to the Japanese pear trees in June but their densities on pear leaves remained low until mid-August. In the pear orchard, the mites initially tended to increase on pear leaves near the holly trees and then gradually spread to other leaves farther away from the holly trees. Their highest density in the pear orchard occurred in mid-October. When pear leaves were inoculated with two or five female adults at different times from May to September, the leaves inoculated before mid-August showed no increase in the number of mites. A possible cause for the suppression of the population increase on pear leaves from June to mid-August is discussed. This revised version was published online in November 2006 with corrections to the Cover Date.     

苹果园主要害虫生态调控体系的研究

通过在果园地面种植牧草或花生、油菜等覆盖作物,改善了生态环境,为天敌种群提供了良好的栖息条件和充足猎物,促进天敌群落的早期发展,在4－6月份使树上天敌总量增加60％,地面捕食性天敌增加20倍以上,不仅使苹果蚜、螨高峰期推迟,并使高峰值分别降低39％和1倍以上,使前中期害虫得很好控制。良好的果园生态环境也可促 使周围农田生态系中的天敌因季节性变动向果园迁移,并通过不同生态系之间的运动,扩大天敌种群,达到控制中后期害虫的效果,对优势天敌因季节性变动向果园迁移,并通过不同生态之间的运动,扩大天敌种群,达到控制中后期害虫的效果,对优势天敌在果园生态系中的作用亦做了研究和评价,认为在天敌－害虫相互作用系统中,天敌群落的综合功能是最重要的,针对不同害虫,小花蝽、草蛉、六点蓟马、赤眼蜂等也具有各自的重要作用。通过天敌的人工操纵和补充释放技术以及选择性药剂的筛选运用,在地面覆草,增强天敌功能的基础上,建立起果园主要害虫的生态调控体系,每年可使苹果园比通常减少用农药40％－50％,使果园生态逐步形成良性循环。     

Association of the Decline of Nashi Pears with an MLO

Mycoplasma-like organisms (MLOs) were constantly detected by the DAPI technique and by restriction fragment length polymorphism (RFLP) analysis of PCR-amplified DNA in trees of Pyrus pyrifolia cvs Hosui and Kosui grafted on P. communis, seedlings rootstock with symptoms similar to the slow form of pear decline. These symptoms included upward curling of the leaves along the midrib. Leaves were abnormally thick and later turned reddish while major veins became swollen and brown. Trees with symptoms were usually 4–5 years old and were growing in the major pear areas of central Italy. The incidence of affected trees was particularly high in one orchard adjacent to a pear orchard strongly affected with the slow form of pear decline. In this case the distribution pattern of affected Nashi trees suggests that the causal agent was introduced from the adjacent pear orchard by an aerial vector. Although oriental pears are well-known hosts of the pear-decline agent when used as rootstocks of French cultivars, this is the first report of pear decline in P. pyrifolia varieties.     

Spring colonisation of orchards by Anthonomus pomorum from adjacent forest borders

The early-season dispersal of the overwintered apple blossom weevil, Anthonomus pomorum (L.) (Coleoptera: Curculionidae), is a crucial stage in the colonisation of dwarf apple orchards adjacent to forests. We have conducted release-recapture studies with 1700 to 4000 marked weevils at two orchard sites in Switzerland over 2 years to characterise the spatial and temporal pattern of the dispersal process. The dispersal and colonisation of orchards in spring by overwintered weevils is dependent upon the prevailing temperature.An orientated dispersal from the forest border to the centre of the orchard was observed consistently, irrespective of the angle of the apple tree rows with respect to the forest border or of climatic conditions. The average dispersal distance of the weevils was 19 m. Approximately one third of the weevil population remained on the first tree encountered, the remainder of the population moved over short distances mainly along the tree rows. This dispersal pattern led to a strong edge effect with higher numbers of weevils occurring at the edges adjoining the forests as compared to the centre of orchards. The relevance of these findings to population dynamics and management of the pest is discussed.