A chromosome‐level genome assembly of the woolly apple aphid,Eriosoma lanigerum Hausmann (Hemiptera: Aphididae)

Woolly apple aphid (WAA, Eriosoma lanigerum Hausmann) (Hemiptera: Aphididae) is a major pest of apple trees (Malus domestica, order Rosales) and is critical to the economics of the apple industry in most parts of the world. Here, we generated a chromosome‐level genome assembly of WAA—representing the first genome sequence from the aphid subfamily Eriosomatinae—using a combination of 10X Genomics linked‐reads and in vivo Hi‐C data. The final genome assembly is 327 Mb, with 91% of the assembled sequences anchored into six chromosomes. The contig and scaffold N50 values are 158 kb and 71 Mb, respectively, and we predicted a total of 28,186 protein‐coding genes. The assembly is highly complete, including 97% of conserved arthropod single‐copy orthologues based on Benchmarking Universal Single‐Copy Orthologs (busco ) analysis. Phylogenomic analysis of WAA and nine previously published aphid genomes, spanning four aphid tribes and three subfamilies, reveals that the tribe Eriosomatini (represented by WAA) is recovered as a sister group to Aphidini + Macrosiphini (subfamily Aphidinae). We identified syntenic blocks of genes between our WAA assembly and the genomes of other aphid species and find that two WAA chromosomes (El5 and El6) map to the conserved Macrosiphini and Aphidini X chromosome. Our high‐quality WAA genome assembly and annotation provides a valuable resource for research in a broad range of areas such as comparative and population genomics, insect–plant interactions and pest resistance management.     

Genome mapping of three major resistance genes to woolly apple aphid (Eriosoma lanigerum Hausm.)

Woolly apple aphid (WAA; Eriosoma lanigerum Hausm.) can be a major economic problem to apple growers in most parts of the world, and resistance breeding provides a sustainable means to control this pest. We report molecular markers for three genes conferring WAA resistance and placing them on two linkage groups (LG) on the genetic map of apple. The Er1 and Er2 genes derived from ‘Northern Spy’ and ‘Robusta 5,’ respectively, are the two major genes that breeders have used to date to improve the resistance of apple rootstocks to this pest. The gene Er3, from ‘Aotea 1’ (an accession classified as Malus sieboldii), is a new major gene for WAA resistance. Genetic markers linked to the Er1 and Er3 genes were identified by screening random amplification of polymorphic deoxyribonucleic acid (DNA; RAPD) markers across DNA bulks from resistant and susceptible plants from populations segregating for these genes. The closest RAPD markers were converted into sequence-characterized amplified region markers and the genome location of these two genes was assigned to LG 08 by aligning the maps around the genes with a reference map of ‘Discovery’ using microsatellite markers. The Er2 gene was located on LG 17 of ‘Robusta 5’ using a genetic map developed in a M.9 × ‘Robusta 5’ progeny. Markers for each of the genes were validated for their usefulness for marker-assisted selection in separate populations. The potential use of the genetic markers for these genes in the breeding of apple cultivars with durable resistance to WAA is discussed.     

Susceptibility of fruit from diverse apple and crabapple germplasm to attack from apple maggot (Diptera: Tephritidae)

Apple maggot, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), is a pest of major concern to apple, Malus x domestica (Borkh.) production in eastern North America. Host plant resistance to apple maggot among apple germplasm has been previously evaluated among a small number of exotic Malus accessions and domestic hybrid selections. However, a large number of exotic accessions housed in USDA collections have never been evaluated for their susceptibility to apple pests. Additionally, previous reports of resistance need to be confirmed under both field conditions and with more rigorous laboratory evaluations. Thus, studies were conducted to evaluate the susceptibility of a number of Malus accessions housed at the USDA Plant Genetic Resources Unit "core" collection. Contrary to earlier published reports, these results suggest that some selections previously described as "resistant" are in fact susceptible to both oviposition damage and larval feeding damage by apple maggot. One domestic, disease-resistant apple accession, 'E36-7' is resistant to survival of apple maggot larvae except when the fruit is nearly ripe in late fall. This is the first report of an apple cultivar that is confirmed to be resistant to larval feeding of apple maggot. Although adults can successfully oviposit on all accessions examined, larval survival was zero in a number of small-fruited crabapple accessions classified as resistant in previous studies and also in two accessions, Malus tschonoskii (Maxim) C. K. Schneid. and M. spectabilis (Aiton) Borkh., that have not been previously evaluated.     

Molecular interactions between rosy apple aphids, Dysaphis plantaginea, and resistant and susceptible cultivars of its primary host Malus domestica

The use of crop varieties resistant or tolerant to insect pests or other stress factors is one approach in non‐chemical crop‐protection. Knowledge of the biochemical and molecular background of insect–plant interactions is a prerequisite for optimizing breeding for resistance. However, the resistance genes involved in plant–aphid interactions have so far only been identified and characterized in very few plant species. Our work aims to elucidate the molecular and biochemical mechanisms involved in resistance of apple trees, Malus domestica L. (Rosaceae), against its primary aphid pest, the rosy apple aphid, Dysaphis plantaginea (Passerini) (Homoptera: Aphididae), which is considered a serious economic pest of apple. Gene expression in both resistant and susceptible apple cultivars after infestation with rosy apple aphids was investigated by employing the cDNA‐AFLP method (cDNA–Amplified Fragment Length Polymorphism). From approximately 12 500 cDNA fragments detected on polyacrylamide gels, 21 bands were apparently up‐ or down‐regulated only in the resistant cultivar ‘Florina’ after aphid infestation compared to the susceptible cultivar ‘Topaz’ and/or mechanically wounded or non‐infested leaves. These fragments were cloned, sequenced, and the pattern of gene expression for six fragments was subsequently verified by virtual Northern blots. Sequence comparisons of these fragments to GenBank accessions revealed homologies to already known genes, most of them isolated from Arabidopsis thaliana L. Among them, a putative RNase‐L‐inhibitor‐like protein, a pectinacetylesterase, an inositol‐phosphatase‐like protein, a precursor of the large chain of the ribulose‐1,5‐biphosphate‐carboxylase, and defence‐related genes such as a vacuolar H(+)‐ATPase subunit‐like protein and an ADP‐ribosylating enzyme were identified. The results are discussed in relation to a putative role of these genes in conferring aphid resistance in apple trees.     

Susceptibility of fruit from diverse apple and crabapple germplasm to attack by plum curculio (Coleoptera: Curculionidae)

Plum curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), is an important apple, Malus domestica Borkh., pest that significantly hinders sustainable apple production in eastern North America. The potential for host plant resistance to plum curculio among apple germplasm has never been rigorously evaluated. Thus, studies were conducted to assess the susceptibility of a number of exotic and domestic Malus accessions housed at the USDA Plant Genetic Resources Unit (PGRU) "core" collection in Geneva, NY. Contrary to earlier published reports and promising data from a field assessment in 2005, these results suggest that there is probably little potential for genetic resistance to plum curculio among the Malus germplasm collection evaluated. More specifically, four Malus hybrid selections that have previously been released with claims of plum curculio resistance were shown to be susceptible to plum curculio attack. Because there are additional accessions housed at PGRU outside of the core collection that are currently classified as resistant, further studies are necessary to evaluate the true resistance qualities of these releases. It is also important to clarify such discrepancies in both the USDA online Germplasm Resources Information Network and in the horticultural literature. Although other Malus species exhibited some variability in fruit susceptibility, none could be classified as being truly resistant to plum curculio attack by any definition that would have relevance to commercial production and sale of apples.     

不同苹果品种对褐斑病抗性的鉴定及抗性生理研究

对42个苹果栽培品种叶片褐斑病进行了田间发病状况调查与抗性鉴定,分析了叶片气孔密度和大小与抗病性之间的关系,同时研究了不同抗性品种离体叶片接种病原菌后超氧化物歧化酶（SOD）、多酚氧化酶（vPo）、过氧化物酶（POD）、苯丙氨酸解氨酶（PAL）活性和木质素含量的差异变化。依照抗性分级标准,供试材料中抗病品种有14个（其中高抗品种2个）,感病品种有28个（其中高感品种7个）;叶片气孔密度与病情指数之间存在显著正相关,相关系数r=0．683;叶片接种后,诱导了4种酶活性和木质素含量的升高,抗病和感病品种的SOD和PP0活性无显著差异,而抗病品种的POD和PAL活性以及木质素含量显著高于感病品种。苹果叶片的气孔密度、POD和PAL的活性以及木质素含量与褐斑病抗性有关。     

Aphis pomi (Hemiptera: Aphididae) population development, shoot characteristics, and antibiosis resistance in different apple genotypes

In high-value crops such as apple, Malus X domestica (Borkh.), insecticidal pest control is of high relevance. The use of resistant apple cultivars can increase the sustainability of pest management in apple orchards. Besides variation in plant chemistry that may influence plant resistance by antibiosis or antixenosis, plant growth characteristics also can affect plant susceptibility to pests such as aphids. Variable susceptibility to the apple aphid, Aphis pomi De Geer (Hemiptera: Aphididae), has been described for different apple cultivars. These observations were based on phenotypic surveys and no information on genetically based apple resistance to A. pomi is yet available. The objective of this study was to relate shoot growth characteristics with aphid population development, and to assess the genetic background of apple antibiosis-based resistance to A. pomi by quantitative trait loci (QTL) analysis. Aphid population development was repeatedly studied in the field in sleeve cages attached to 200 apple trees of different genotypes. Aphid population development was positively correlated to shoot length and growth, and it also was affected by climatic conditions. Indications for antibiosis-based resistance to A. pomi remained weak in the studied apple genotypes, and the only detected putative QTL on linkage group 11 of'Fiesta' apples was not stable for the different replications of the experiment. This lack of quantifiable resistance may be partly explained by environmental conditions related to aphid development in sleeve cages.     

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。     

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.     

小麦种质对麦长管蚜的抗性鉴定与评价

2002-2005年连续4年,选用蚜情指数法对小麦种质进行麦长管蚜田间自然感蚜抗性鉴定,从2000份小麦种质中筛选出不同抗性材料34份,占总鉴定材料的1.7%,其中高抗种质5份、抗性种质9份、中抗种质20份。利用苗期室内接虫法,对部分抗感小麦种质进行鉴定,结果表明,苗期的抗性表现与成株期基本一致。对杂交组合临远207(抗)×Witchita(感)的F1、F2的抗性遗传分析表明,临远207对麦长管蚜的抗性由1对显性单基因控制。     

QTL analysis for aphid resistance and growth traits in apple

The rosy apple aphid (Dysaphis plantaginea), the leaf-curling aphid (Dysaphis cf. devecta) and the green apple aphid (Aphis pomi) are widespread pest insects that reduce growth of leaves, fruits and shoots in apple (Malus × domestica). Aphid control in apple orchards is generally achieved by insecticides, but alternative management options like growing resistant cultivars are needed for a more sustainable integrated pest management (IPM). A linkage map available for a segregating F₁-cross of the apple cultivars ‘Fiesta’ and ‘Discovery’ was used to investigate the genetic basis of resistance to aphids. Aphid infestation and plant growth characteristics were repeatedly assessed for the same 160 apple genotypes in three different environments and 2 consecutive years. We identified amplified fragment length polymorphism (AFLP) markers linked to quantitative trait loci (QTLs) for resistance to D. plantaginea (‘Fiesta’ linkage group 17, locus 57.7, marker E33M35–0269; heritability: 28.3%), and to D. cf. devecta (‘Fiesta’ linkage group 7, locus 4.5, marker E32M39–0195; heritability: 50.2%). Interactions between aphid species, differences in climatic conditions and the spatial distribution of aphid infestation were identified as possible factors impeding the detection of QTLs. A pedigree analysis of simple sequence repeat (SSR) marker alleles closely associated with the QTL markers revealed the presence of the alleles in other apple cultivars with reported aphid resistance (‘Wagener’, ‘Cox’s Orange Pippin’), highlighting the genetic basis and also the potential for gene pyramiding of aphid resistance in apple. Finally, significant QTLs for shoot length and stem diameter were identified, while there was no relationship between aphid resistance and plant trait QTLs. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

用海棠苗饲养苹果绵蚜的方法

报道了用1年生海棠苗作为寄主植物饲养苹果绵蚜Eriosomalanigerum(Hausmann)的方法,包括寄主植物的选取、栽培管理、接虫方法及试验结果。该方法既能为苹果绵蚜提供长期新鲜的寄主植物,又能使仔蚜很快定殖成活,十分有利于试验的连续进行,且简单经济。     

夏季苹果新梢生理指标与抗苹果绵蚜的关系

研究苹果生理指标与其对苹果绵蚜(Eriosoma lanigerum Hausmann)抗性的关系,为筛选培育抗性品种,实现持续有效治理苹果绵蚜提供依据.田间调查不同苹果品种对苹果绵蚜的抗性,测定比较各品种正常枝条生理指标,以及被苹果绵蚜危害后生理指标的变化.结果表明,正常枝条中可溶性糖(r=0.99)、蛋白质(r=0.86)含量与感蚜率呈正相关;氨基酸含量与感蚜率呈负相关(r=-0.96);酚类物质和4种酶活性与苹果感蚜率均不存在明显相关性.被害后昭锦108可溶性糖含量有所下降,红富士、金冠分别上升1.4％、7.0％;蛋白质、氨基酸、酚类物质含量均有所下降,其中红富士总酚含量明显下降,达23.5％,总酚下降率与感蚜率呈正相关(r=0.94);超氧化物歧化酶(Superoxide Dismutase,SOD)、过氧化氢酶(Catalase,CAT)活性均上升,其中CAT变化率与感蚜率存在相关性(r=-0.92),昭锦108 CAT活性明显上升,达91.2％;多酚氧化酶(Polyphenol Oxidase,PPO)、过氧化物酶(Peroxidase,POD)活性增减不一;金冠4种酶活性均上升.研究表明,对苹果绵蚜抗性较强的品种:可溶性糖、蛋白质含量较低,游离氨基酸含量较高;受害后可溶性糖含量下降,总酚含量下降率较低,游离氨基酸含量下降率较高.酶活性对抗蚜性的影响不明显.     

Laboratory and field studies supporting the development of Heringia calcarata as a candidate biological control agent for Eriosoma lanigerum in New Zealand

Studies supporting a project seeking to introduce Heringia calcarata (Loew) (Diptera: Syrphidae) to New Zealand (NZ) to supplement biological control of woolly apple aphid (WAA), Eriosoma lanigerum (Hausmann) (Hemiptera: Aphididae) are reported. Annual surveys of H. calcarata presence and abundance in a Virginia, USA apple orchard revealed a bimodal distribution, with peaks in mid-June and mid-September. In the field, female H. calcarata oviposited on sentinel apple shoots infested with WAA, providing an efficient method for egg collection and larval production. Similarly, most field-collected females readily deposited viable eggs on WAA colonies in laboratory cages, demonstrating that mated females will oviposit in captivity. Survivorship of eggs and larvae transported to NZ was good, yielding adult flies in containment in Auckland. Adult, virgin female H. calcarata reared from eggs in captivity developed mature oocytes, providing an important step toward future mating studies in containment. Oviposition and larval feeding studies examined aspects of the intraguild interactions between H. calcarata and Aphelinus mali (Haldeman) (Hymenoptera: Aphelinidae), the sole biological control agent of WAA in NZ. Field tests using paired sentinel apple shoots with a non-parasitized or parasitized WAA colony revealed that although H. calcarata deposited eggs on both parasitized and non-parasitized colonies, fewest eggs were deposited on heavily parasitized colonies. Feeding studies showed that larval H. calcarata consumed fewer mummified aphids or aphids in an earlier stage of parasitization than non-parasitized aphids.     

Evidence for single gene resistance in apple to brownheaded leafroller, Ctenopseustis obliquana, and implications for resistance to other New Zealand leafrollers

The survival and development rate of Ctenopseustis obliquana (Walker) (Lepidoptera: Tortricidae) larvae, and weight of pupae were measured on detached mature leaves of two apple (Malus domestica Borkh.) progenies derived from the resistant (R) parent ‘Prima’ crossed with the susceptible (S) cultivars ‘Liberty’ (n = 44) and ‘Red Delicious’ (n = 35). The R:S ratio in both these modified backcross families did not differ significantly from the 1:1 expected in the case of monogenic resistance, carried in a heterozygous condition in the resistant parent. The survival to pupation on the individual seedlings was either zero/very low (R) or high (S). With all resistant seedlings being heterozygous, this indicates that the resistance allele shows complete dominance over the susceptible allele. We have named this putative gene Cob1. The expression of the resistance was found to be influenced by both the colony of C. obliquana used and the time of the season when resistance was assessed. In a separate experiment with another tortricid, there was no survival of Planotortrix octoDugdale larvae on the apple cultivar ‘Prima’ and high survival on the cultivars ‘Liberty’ and ‘Red Delicious’. The similarity of the responses of the two leafroller species to these cultivars, and other published evidence concerning Planotortrix excessana (Walker) and Ctenopseustis herana(Felder and Rogerhofer), suggest that the resistance discovered to C. obliquana may be effective against all four endemic tortricid species. The implications of these findings for apple breeding and leafroller control in New Zealand are discussed.     

The Vh8 locus of a new gene-for-gene interaction between Venturia inaequalis and the wild apple Malus sieversii is closely linked to the Vh2 locus in Malus pumila R12740-7A

The wild apple (Malus sieversii) is a large-fruited species from Central Asia, which is used as a source of scab resistance in cultivar breeding. Phytopathological tests with races of Venturia inaequalis were performed to differentiate scab-resistance genes in Malus as well as an avirulence gene in the pathogen. A novel gene-for-gene interaction between V. inaequalis and Malus was identified. The locus of the scab-resistance gene Vh8 is linked with, or possibly allelic to, that of the Vh2 gene in Malus pumila Russian apple R12740-7A, at the lower end of linkage group 2 of Malus. Race 8 isolate NZ188B.2 is compatible with Vh8, suggesting the loss or modification of the complementary AvrVh8 gene, while isolate 1639 overcomes both Vh2 and Vh8, but is incompatible with at least one other gene not detected by any of the other race isolates tested. Our research is the first to differentiate scab-resistance genes in a putative gene cluster in apple with the aid of races of V. inaequalis.     

Predictive thresholds for forecasting the compatibility of <Emphasis Type="Italic">Forficula auricularia</Emphasis> and <Emphasis Type="Italic">Aphelinus mali</Emphasis> as biological control agents against woolly apple aphid in apple orchards

The woolly apple aphid (WAA), Eriosoma lanigerum (Hausmann) (Hemiptera: Aphididae) is a well-known pest of apple orchards world-wide. Several studies have demonstrated variable control of WAA populations by the European earwig, Forficula auricularia (L.) (Dermaptera: Forficulidae) and the WAA parasitoid Aphelinus mali (Halderman) (Hymenoptera: Aphelinidae). We examine whether a beneficial interaction between F. auricularia and A. mali exists and calculate optimal numbers for each species to maintain WAA infestations below acceptable levels. We demonstrate that trees possessing >14 earwigs per trunk trap per week within the first seven weeks post-blossom contained WAA infestations well below acceptable levels. Where these earwig thresholds were not met, a first generation of A.mali greater than 0.5 wasps per tree was required. If these beneficial insect targets were not met, severe WAA infestations occurred. Our findings suggest that if F. auricularia and A. mali numbers exceed these thresholds chemical intervention may not be required.     

Assessment of the potential for and development of organophosphorus resistance in field populations of Myzus persicae

A survey of esterases in field populations of the peach-potato aphid, Myzus persicae was made during the spring of 1975. Assay was by electrophoresis of single aphid homogenates, and the known association between the activity of an esterase and resistance to organophosphorus insecticide (OP) was used to infer resistance in field populations. The resistant variant replaced the susceptible in populations which had been treated with OP and another variant with threefold (approximately) more esterase activity appeared to be replacing the resistant variant in populations which have been treated twice with OP. The significance of this for control of M. persicae is discussed. Differences in resistance between aphids in different parts of the same field, and the widespread association of these esterase variants in favoured combinations with two electrophoretic variants at another locus have also been investigated.     

苹果果实中几种生化物质的含量与抗采后炭疽病的关系

接种炭疽菌前与苹果果实品种的病情指数呈正相关的生化物质是果实中的可溶性总糖含量(r=0.9978),负相关的生化物质是果实中的木质素(r=-0.9811)和绿原酸含量(r=-0.9939),接种前果实的总酸含量与品种的病情指数无关;接种后48和96 h的寄主体内可溶性总糖和有机酸含量有增有减,病情指数不同的品种变幅不同,接种96 h后果实中总酸含量与品种的病情指数呈现负相关(r=-0.9412),木质素和绿原酸含量都呈上升趋势,抗病品种的增幅高于感病品种。     

Resistance of Glycine species and various cultivated legumes to the soybean aphid (Homoptera: Aphididae)

The soybean aphid, Aphis glycines Matsumura, is a new pest of soybean, Glycine max (L.) Merr., in North America. It has become widespread on soybean in North America since it was first identified in the Midwest in 2000. Species of Rhamnus L. (buckthorn) are the primary hosts of A. glycines, and soybean is known as a secondary host. There is limited information about the secondary host range of A. glycines. Aphid colonization on various legume hosts was compared in choice experiments. Aphid colonization occurred on species in the genus Glycine Wild. No colonization occurred on Lablab purpureus (L.) Sweet, Lens culinaris Medik, Phaseolus vulgaris L., Pisum sativum L., or species of Vicia L. and Vigna Savi. Colonization was limited or aphids were transient on species of Medicago L., Phaseolus L., and Trifolium L. There were significant differences in aphid colonization among Medicago truncatula accessions with numbers ranging from 7 to 97 aphids per plant. Six Glycine soja Sieb. & Zucc. accessions were as resistant as G. max accessions to A. glycines; these may represent novel sources of A. glycines resistance not found in G. max. Antibiosis was found to play a large role in the expression of resistance in three of the G. soja accessions. Results of this study indicated that G. max and G. soja were the best secondary hosts of A. glycines; however, its secondary host range may include other leguminous species. Therefore, A. glycines did not seem to have a highly restricted monophagous secondary host range.