Abundance and natural control of the woolly aphid <Emphasis Type="Italic">Eriosoma lanigerum</Emphasis> in an Australian apple orchard IPM program

Woolly aphid (Eriosoma lanigerum Hausmann) (Hemiptera: Aphididae), was monitored over three growing seasons (1995--1998) to assess its abundance and management under apple IPM programs at Bathurst on the Central Tablelands of NSW, Australia. Woolly aphid infestations were found to be extremely low in IPM programs utilising mating disruption and fenoxycarb for codling moth Cydia pomonella L. (Lepidoptera: Tortricidae) control. This was the direct result of increased numbers of natural enemies. No insecticides were applied for woolly aphid control. Under the IPM strategies tested the principal control agent was identified as European earwig (Forficula auricularia L.) (Dermaptera: Forficulidae). Earwigs in combination with Aphelinus mali (Haldeman) (Hymenoptera: Aphelinidae) reduced woolly aphid infestations below the action threshold set by commercial growers. However, A. mali together with other flying natural enemies, e.g., ladybirds, lacewings and hoverflies, did not provide commercially acceptable control of woolly aphid in the absence of earwigs. Under the conventional spray program, using the broad-spectrum insecticide azinphos-methyl for codling moth control, the level of woolly aphid infestation increased with each successive season and biological control was not established. When azinphos-methyl was withdrawn, natural enemies migrated in and provided control of woolly aphid within one season. This is the first study to show that the biological control of woolly aphid can be achieved in a commercially viable IPM program.     

Control of woolly aphid, Eriosoma lanigerum (Hausmann) (Hemiptera: Pemphigidae) on mature apple trees using insecticide soil-root drenches

Abstract Woolly aphid, Eriosoma lanigerum , is an important pest of apples that infests both the aerial and root parts of the tree. Root colonies are protected from the pesticide sprays applied during the growing season and the climatic effects of winter. Consequently, root colonies are a major source of aerial re-infestation in the following spring. Imidacloprid, the first of a new group of insecticides from the chloronicotinyl family, is known to provide excellent control of woolly aphid on trees up to 7-years-old when applied as a root soil drench. This study compared the effects of a single application of chlorpyrifos, imidacloprid, pirimicarb or vamidothion, applied as a root drench over four growing seasons. A soil wetting agent was added to each chemical to improve soil saturation and penetration. Imidacloprid provided excellent control of woolly aphid on the trees that were 17-years-old at the start of the study and continued to do so for four seasons. Pirimicarb appeared to offer some suppression of woolly aphid during the first season but not in subsequent seasons, while chlorpyrifos and vamidothion failed to control woolly aphid in any season. The potential role for imidacloprid in IPM programs is discussed.     

Feeding and egg distribution studies of Heringia calcarata (Diptera: Syrphidae), a specialized predator of woolly apple aphid (Homoptera: Eriosomatidae) in Virginia apple orchards

Predation by the aphidophagous syrphid fly Heringia calcarata (Loew) on woolly apple aphid, Eriosoma lanigerum (Hausmann), was studied in the laboratory and in Virginia apple orchards. Feeding studies compared the prey suitability of three temporally sympatric aphid pests of apple: spirea aphid, Aphis spiraecola Patch; rosy apple aphid, Dysaphis plantaginea (Passerini); and woolly apple aphid. Significantly more H. calcarata larvae survived and completed development on a pure diet of woolly apple aphid than on rosy apple aphid, and none survived on spirea aphid. Final larval weights were significantly greater, and the larval developmental period was significantly shorter on woolly apple aphid than on rosy apple aphid, but neither the duration of pupal development nor adult weight differed between diets. H. calcarata larvae consumed an average of 105 woolly apple aphids during their development. Na?ve, neonate larvae given access to all possible pair combinations of woolly apple aphid, rosy apple aphid, and spirea aphid consumed significantly more woolly apple aphids in all pairings that included woolly apple aphid. When given a choice of rosy apple aphid and spirea aphid, significantly more rosy apple aphids were consumed. Weekly counts of syrphid eggs found in woolly apple aphid, rosy apple aphid, and spirea aphid colonies collected from apple trees showed that two generalist hover fly predators, Eupeodes americanus (Wiedemann) and Syrphus rectus Osten Sacken, were present in colonies of all three aphid species and that E. americanus was the most abundant syrphid predator in A. spiraecola and D. plantaginea colonies. H. calcarata eggs were found only in woolly apple aphid colonies and were more abundant there than E. americanus and S. rectus. These data suggest that H. calcarata is a specialized predator of woolly apple aphid in the apple ecosystem in Virginia.     

Arthropod abundance in an Australian apple orchard under mating disruption and supplementary insecticide treatments for codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae)

The impacts of three codling moth management strategies (i, mating disruption alone; ii, mating disruption plus azinphos-methyl; iii, mating disruption plus fenoxycarb) on some secondary pests and their natural enemies in an apple orchard were compared over two growing seasons: 1993/1994 and 1994/1995. In the absence of azinphos-methyl (strategies i and iii), two-spotted mite ( Tetranychus urticae ) was controlled by Typhlodromus occidentalis and populations of generalist predators (e.g. ladybirds, lacewings and earwigs) increased. The populations of a parasitoid of woolly aphid ( Eriosoma lanigerum ), Aphelinus mali, also increased but not enough to provide adequate control of the aphid. Combined damage caused by lightbrown apple moth ( Epiphyas postvittana ), budworms ( Helicoverpa spp.) and San José scale ( Quadraspidiotus perniciosus ) was significantly higher in the absence of azinphos-methyl in 1994/1995. Beneficial insect populations were not suppressed by fenoxycarb. In 1994/1995, mating disruption plus fenoxycarb produced better control of E. postvittana than mating disruption alone. During transition to an apple integrated pest management program based on codling moth mating disruption, fenoxycarb was shown to be less disruptive to any natural control of secondary pests than azinphos-methyl.     

苹果绵蚜与苹果绵蚜日光蜂种间关系的模拟研究——Ⅱ.自然系统的模拟及灵敏度分析

本文在生物学特性研究的基础上,组建了苹果绵蚜(Eriosoma lanigerum)及其日光蜂(Aphelinus mali)寄主——天敌作用系统的Boxcar train模型,对苹果绵蚜猖獗期的二种群数量进行了模拟,其结果与果园调查基本吻合。用此模型做系统的灵敏度分析,结果表明系统的内部因子(如蚜蜂的基数比例)和外部因子(温湿度)对系统均有影响。温度升高,二种群数量增加,反之则下降。湿度增加,苹果绵蚜日光蜂种群数量上升,反之则下降。湿度变化对苹果绵蚜无不良影响。比较而言,温度对系统的影响比湿度大得多。减少苹果绵蚜基数比增加日光蜂基数对系统的影响大,据此可从理论上估计生物防治的局限性。     

苹果绵蚜密度及聚集度对日光蜂寄生作用的影响

苹果绵蚜日光蜂(Aphelinus mali Hald.)是苹果绵蚜的主要寄生蜂。1879年L.O.Howard首次发现了这种寄生蜂。此后,国内外对其生物学特性、杂交育种及在生物防治中的应用作了大量研究。利用日光蜂防治苹果绵蚜的效果一方面取决于它的生物学和生态学特性。日光蜂世代历期、食性范围、寄生时期和绵蚜活动时期的重叠度、日光蜂自然增长率、日光蜂自身密度和环境适应能力等都会影响它的寄生效果。     

Effect of fungicide application on activity of Neozygites fresenii (Entomophthorales: Neozygitacaea) and cotton aphid (Homoptera: Aphididae) suppression

The development of resistance in aphid populations highlights the importance of biological control as a pest management tactic. Four treatments were evaluated to determine the effects of pesticides on the population dynamics of Aphis gossypii Glover and Neozygites fresenii (Nowakowski) Batko: (1) weekly applications of the insecticide imidacloprid (Provado 1.6 F); (2) weekly applications of the fungicide chlorothalonil (Bravo 720); (3) applications of imidacloprid (Provado 1.6 F) when aphid densities exceeded 30 aphids per leaf, and (4) untreated control. Differences in aphid density among the four treatments were shown only to be significant during the 1997 growing season; however, aphid densities were greater in the chlorothalonil treatment than in the other treatments during each growing season. Percentage of N. fresenii-killed aphids was most often highest in the chlorothalonil treatment as well. The fungal epizootic caused by N. fresenii was delayed approximately 1 wk in the chlorothalonil treatment when compared with the other treatments. This delay allowed the aphids to temporarily escape suppression by the fungus and to continue to increase in density until the density-dependent effects of the epizootic overwhelmed the aphid population. N. fresenii also appeared to persist in the system when imidacloprid was in use and does appear responsible for initial aphid reductions. Treatment did not appear to have a large influence on yield outcome. Yield was variable from year to year and from location to location.     

Genome mapping of an apple scab,a powdery mildew and a woolly apple aphid resistance gene from open-pollinated Mildew Immune Selection

Apple is host to a wide range of pests and diseases, with several of these, such as apple scab, powdery mildew and woolly apple aphid, being major causes of damage in most areas around the world. Resistance breeding is an effective way of controlling pests and diseases, provided that the resistance is durable. As the gene pyramiding strategy for increasing durability requires a sufficient supply of resistance genes with different modes of action, the identification and mapping of new resistance genes is an ongoing process in breeding. In this paper, we describe the mapping of an apple scab, a powdery mildew and a woolly apple aphid gene from progeny of open-pollinated mildew immune selection. The scab resistance gene Rvi16 was identified in progeny 93.051 G07-098 and mapped to linkage group 3 of apple. The mildew and woolly aphid genes were identified in accession 93.051 G02-054. The woolly aphid resistance gene Er4 mapped to linkage group 7 to a region close to where previously the genes Sd1 and Sd2, for resistance to the rosy apple leaf-curling aphid, had been mapped. The mildew resistance gene Pl-m mapped to the same region on linkage group 11 where Pl2 had been mapped previously. Flanking markers useful for marker-assisted selection have been identified for each gene.     

Comparison of a Canadian and a Dutch strain of the parasitoid Aphelinus mali (Hald) (Hym., Aphelinidae) for control of woolly apple aphid Eriosoma lanigerum (Haussmann) (Hom., Aphididae) in the Netherlands: a simulation approach

Woolly apple aphid, Eriosoma lanigerum is one of the important apple pests in the Netherlands. Weather conditions and natural enemies determine whether woolly apple aphid (WAA) will reach pest status. WAA may escape control by natural enemies and therefore it must be controlled using chemical insecticides. To prevent unnecessary applications of insecticides and to promote biological and natural control of WAA more knowledge is needed about the role of natural enemies, weather and their effects on the development of WAA populations. The monophagous parasitoid Aphelinus mali (Hald.) has been introduced into most of apple growing areas to control WAA, but success is variable and depends on climatological conditions. In the Netherlands the level of parasitization is often too low, especially after warm winters. The biological control potential of a strain of A. mali from Nova Scotia (Canada) was compared with a Dutch strain by simulating population growth of both WAA and the Dutch and Canadian strain of the parasitoid for three different years The results indicate that the Canadian strain would perform in general better than the Dutch strain under Dutch weather conditions.     

苹果绵蚜对不同苹果品种春梢生长期生理指标的影响

为了筛选培育对苹果绵蚜(Eriosoma lanigerum Hausmann)的抗性品种,实现持续有效治理苹果绵蚜的目的,通过测定红富士、金帅、昭锦108、秦冠、红将军等5种不同苹果品种春梢生长期被苹果绵蚜危害前后枝条内可溶性糖、蛋白质、游离氨基酸、总酚含量以及防御性酶的活性变化,探讨苹果生理指标与抗蚜性的关系。结果表明,被害后可溶性糖含量除红将军外均有所上升,其中红富士上升达13.7%;蛋白质含量除红富士外均有所降低;氨基酸含量均有所上升,其中红将军变化明显,变化率达68.8%。酚类物质是一种重要的抗蚜物质,红富士、昭锦108、秦冠被害后总酚含量均升高,其中昭锦108、秦冠中总酚含量上升率约为红富士的2倍。红富士品种正常枝条内超氧化物歧化酶(Superoxide Dismutase,SOD)、多酚氧化酶(Polyphenol Oxidase,PPO)、过氧化物酶(Peroxidase,POD)以及过氧化氢酶(Catalase,CAT)活性均显著低于昭锦108,被害后各苹果枝条SOD活性均出现上升趋势,除红将军的PPO、POD活性降低外,其他品种均升高;金帅、红富士的CAT活性上升明显,分别为110.8%、45.5%。植物的防御性酶与其抗虫性有密切关系,苹果春梢生长期对苹果绵蚜的抗性与苹果体内的可溶性糖、游离氨基酸、SOD、PPO、POD以及CAT活性均有关,而且不同苹果品种被害后生理指标的变化也与其抗蚜性有一定关系。     

Genetic diversity of woolly apple aphid Eriosoma lanigerum (Hemiptera: Aphididae) populations in the Western Cape, South Africa

The woolly apple aphid Eriosoma lanigerum (Hausmann) is one of the most damaging apple pests in South Africa. Information on its genetic diversity is lacking and this study, in which the genetic structure of parthenogenetic E. lanigerum populations was characterized in the Western Cape Province of South Africa, represents the first local study of its kind. A total of 192 individuals from four different regions were collected and analysed using amplified fragment length polymorphism (AFLP). Using five selective AFLP primer pairs, 250 fragments were scored for analysis. Results indicated that a low level of genetic variation was apparent in E. lanigerum populations in the Western Cape (H = 0.0192). Furthermore, populations collected from geographically distant regions were very closely related, which can partly be explained by the fact that agricultural practices were responsible for dissemination of populations from a common ancestor to geographically distant areas. The low level of variation found indicated that the possibility of controlling E. lanigerum in the Western Cape using host plant resistance is favourable. This is the first report of AFLP being used to characterize the genetic structure of an aphid species. Results indicate that this marker may be useful for analysis of other aphid species.     

Spatial variation of woolly apple aphid (

There is an increasing requirement to breed durable resistances to woolly apple aphid (WAA) into apple cultivars. Genetically diverse apple plantings have been established in New Zealand with one aim to identify new sources of resistance to this pest, and also to allow the computation of parameters of genetic interest. Such computations are hindered by the uneven distribution of the pest in the orchard. The spatial distribution of WAA was investigated using local trend surfaces to examine large scale patterns, and point process analyses to check for the presence of small scale clumping. Large scale patterns in WAA distribution were found which could be attributed to the degree of exposure of the trees, and clumping was also detectable. The experimental design was found to adequately accommodate these spatial patterns. The application of the point process analysis to other ecological situations, and manners in which it could be extended, are discussed.     

Sex ratios in natural populations ofAphelinus mali (Hym.: Aphelinidae) in relation to host size and host density

In an apple orchard at Armidale, the Northern Tablelands of NSW, population sex ratios ofAphelinus mali (Haldeman), an endoparasitoid of the woolly apple aphid,Eriosoma lanigerum (Hausmann) varied from 0.51 (proportion of males) at low host densities to female-biased at high host densities (proportion of males ranged from 0.35–0.39). This shift in sex ratio seems to be caused by the differences in allocation of sons and daughters to hosts of different sizes. In the fieldA. mali parasitizes all life stages (four nymphal instars and adult) of the woolly aphid upon encountering. According to Hughes'(1979) optimal diet model, such general host acceptance seems to be the best strategy. However, it allows the host nymphs or adults to continue to develop or reproduce until about to mummify (pupate). No mortality was observed when first or second-instar hosts were parasitized in the laboratory. Field collected small mummified hosts yielded male-biased sex ratios whereas large mummified hosts produced mainly females. In the laboratory, progeny from smaller hosts (first to third-instars) produced sex ratios which were not significantly different from 0.5 whereas progeny from larger hosts (third and fourth-instars) produced female-biased sex ratio. During winter (June–August) and early spring (September–October) when the host populations in the orchard were predominantly nymphs, the parasitoid tended to allocate equal resources to male and female offspring. In contrast, at peak population densities in summer and autumn (December–May) when larger hosts were available, the sex ratios were female-biased. The host size ofE. lanigerum andA. mali is, therefore, an important component in the dynamics of host-parasitoid interactions.     

外来入侵种——苹果绵蚜在中国的适生区预测

苹果绵蚜Eriosoma lanigerum(Hausmann)是我国重要的检疫性害虫,主要为害苹果、海棠等苹果属(Malus Mill.)植物。目前,该种害虫已在我国一些苹果主产区迅速扩散,并给我国的苹果产业造成了较为严重的经济损失。为了对其进行有效监控,控制其蔓延,制定合理的防治策略,本研究利用GARP和MAXENT两种生态位模型,结合其寄主地理分布,预测苹果绵蚜在我国的潜在地理分布区。研究结果表明:GARP和MAXENT预测结果相似,但前者预测面积比后者广泛。苹果绵蚜在我国的最适适生区主要分布在东北(辽宁南部)、华北(河北东、南部、北京、天津和山西南部)、华东(山东大部)、华中(河南北部)和西北(陕西中部)。另外,河北南部、山东和河南南部、甘肃东部、四川中南部、陕西大部、云南与西藏的零星地区是苹果绵蚜的中度适生区;黑龙江、吉林、新疆等20个省份(市、自治区)的全境是苹果绵蚜低度适生区或不适生区。此外,刀切法(Jackknifetest)检验结果表明,1月份平均最高温是影响苹果绵蚜分布最重要的环境变量。最后,提出几点管理苹果绵蚜的方法和防治策略,避免该种害虫传播或入侵到其它苹果产区。     

Herbivore regulation in urban agroecosystems: Direct and indirect effects

Urban agroecosystems can provide habitat for biodiversity and can benefit human communities through urban food provisioning. Moreover, urban agroecosystems could be managed so as to optimize ecosystem services like natural pest control provided by trophic interactions between natural enemies and herbivores. As in other ecosystems, predation and parasitism regulate herbivores in urban settings, but less is known about the relative importance of direct and indirect effects at local and landscape scales in highly managed urban agroecosystems. We collected data on herbivore (cabbage aphid) density and parasitism ratios (proportion of parasitized aphid “mummies”) in 25 community gardens in three counties in the California central coast, USA. We used structural equation modeling to examine the effects of direct factors (host plant characteristics and parasitism) and indirect factors (soil, garden, and landscape characteristics) on herbivore density changes at two time points in the growing season (June and August). Aphid density, but not parasitism, varied across counties over the season, and there was a strong negative relationship between aphid density and parasitism. Direct effects were strong drivers of aphid density but not parasitism. In June, aphid density increased with host plant volume but decreased with greater floral density, while parasitism was only influenced by aphid density. In August, host plant volume similarly positively affected aphid density, and soil water holding capacity increased host plant volume. In addition, host plant density had a strong negative effect on parasitism. Urban gardeners may be able to reduce aphid pest densities by increasing floral resource density and strategically spatially distributing host plants throughout garden beds, though these processes depend on the season. The indirect effects of soil water holding capacity on aphid densities further suggest a critical role of human management on pest populations and pest control services through soil amendments and irrigation.     

Characteristics associated with Woolly Apple Aphid Eriosoma lanigerum, resistance of three apple rootstocks

The resistance characteristics of the apple resistance genes (Er1, Er2, and Er3) to the woolly apple aphid, Eriosoma lanigerum (Hausmann) (Homoptera: Aphididae) were studied according to the performance measured on apple cultivars containing these resistance genes. The resistance characteristics of Northern Spy (Er1), Robusta 5 (Er2), and Aotea (Er3) were compared to the susceptible cultivar Royal Gala, by measuring the aphid settlement, development, and survival rates correlated with electronically monitored probing behaviour. Er1 and Er2 had a higher level of resistance with a significantly shorter period of phloem feeding, suggesting that the resistance factors were present in the phloem tissue. Phenological measurements indicated that the aphids showed poor settlement, development, and survival on Er2. Er1 also showed low settlement and survival, although not as low as Er2. Aphid performance and feeding on Aotea (Er3) were similar to Royal Gala, suggesting that some woolly apple aphids in New Zealand may have recently overcome Er3 resistance. The differences in resistance mechanisms of Er1, Er2, and Er3 are discussed in relation to the strategy of pyramiding these genes to give a durable resistance to woolly apple aphid.     

Rise and fall of cotton aphid (Hemiptera: Aphididae) populations in southeastern cotton production systems

The impact of natural enemies on cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae), populations in cotton, Gossypium hirsutum L., production systems in the southeastern United States was evaluated over 3 yr in irrigated commercial cotton fields. Fungal epizootics caused by the entomopathogen Neozygites fresenii (Nowakowski) Batko reduced aphid numbers to subthreshold levels in 1999, 2000, and 2001 and occurred consistently in early to mid-July in all 3 yr. Scymnus spp. were the most abundant aphidophagous predators, although other coccinellid species and generalist predators such as spiders, fire ants, heteropterans, and neuropterans also were present. Studies using arthropod exclusion cages demonstrated little impact of predators or parasitoids on aphid populations before fungal epizootics. Arthropod natural enemies were most abundant after epizootics and may have suppressed aphid populations late in the season. Seed cotton yield, and lint quality were not affected by aphicide applications in any year of the study. Implications of these findings for aphid management in the southeastern United States are discussed.     

Kaolin particle films suppress many apple pests, disrupt natural enemies and promote woolly apple aphid

Multiple applications of hydrophobic kaolin particle film in apple orchards suppressed numbers of blossom weevil (Anthonomus pomorum), brown leaf weevil (Phyllobius oblongus), attelabid weevil (Caenorhinus pauxillus), leafhoppers (Empoasca vitis and Zygina flammigera) and green apple aphid (Aphis pomi) colonies. The kaolin treatments reduced the apple sawfly (Hoplocampa testudinea) fruit infestation on cultivar J. Grieve, and the fruit damage caused by oyster scale (Quadraspidiotus ostreaeformis), mussel scale (Lepidosaphes ulmi), early caterpillars, leaf rolling moths (Tortricidae), fruitlet‐mining tortrix moth (Pammene rhediella) and codling moth (Cydia pomonella). There was no effect on the number of colonies of rosy leaf curling aphid (Dysaphis devecta), nor on the fruit damage caused by common earwig (Forficula auricularia) and apple sawfly on cv. G. Delicious. The level of infestation of rosy apple aphid (Dysaphis plantaginea), leaf miner moths (Phyllonorycter blancardella, Lyonetia clerkella), and agromyzid flies (Phytomyza heringiana) increased in the kaolin‐treated plots. Kaolin treatments promoted woolly apple aphid (Eriosoma lanigerum) infestation, which became severe, while it reduced the abundance of polyphagous predators like F. auricularia, predaceous Heteroptera and Coleoptera, the red velvet mite (Allothrombium fuliginosum), spiders (Araneae) and the abundance of common black ant (Lasius niger). The treatments also reduced parasitism of the apple sawfly by the ichneumonid Lathrolestes ensator. Many weeks after ending the kaolin treatments, the number of predaceous Coleoptera and especially the number of spiders remained low in the kaolin‐treated plots.     

Principles of formation of the environment friendly program of management of arthropod pests and their enemies in an apple orchard agroecosystem in the North Caucasus

Ecological inefficiency of conventional IPM programs for apple orchard protection in the North Caucasus results from arbitrary use of compounds producing opposite ecological effects, i.e., broad-spectrum chemical insecticides after environment-friendly selective ones, which destroys the apple orchard agroecosystem. The investigation was aimed at developing an effective and ecologically acceptable program with alternation of environment-friendly compounds which act along the same vector to preserve the populations of natural enemies of the pests and thus to stabilize the apple orchard agroecosystem, i.e., create an ecological type of orchard. In this kind of orchards, broad-spectrum chemical pesticides are prohibited whereas selective biological compounds (including synthetic ones) and methods are welcomed. The test runs of the resulting pest and enemy management (PEM) programs based both on bioregulators (Insegar, Match, Dimilin) and bio-insecticides (Phytoverm™, Lepidocid™, etc.) in 2007 and 2009 demonstrated their high efficiency: the apple fruit damage by codling moth was 1.2% and 0.3%, respectively. The test of sticky bands fixed on apple tree trunks to prevent ants from getting to the crowns showed a significant increase in the abundance of predaceous bugs which sharply reduced the green apple aphid population.