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The aphid Aphis pomi represents an important pest of apples. The use of botanical extracts may be a safe and effective way to control this pest. In this context, we studied the aphicidal and repellent effects of aqueous extracts of Salvia microphylla against A. pomi. Five concentrations were tested on two main aphid parameters: mortality rate and percentage of repellency. The results showed that concentrations of 10% recorded the highest mortality rate (73.33%) and percentage of repellency (62.59%). After further field investigations, the use of S. microphylla may constitute a component of the integrated management of aphids.

Research on the detection of apple leaf disease has been developed. Various methods have been carried out to detect apple leaf disease, one of which is by processing digital images. In this study, the author proposes the Convolutional Neural Network (CNN) algorithm as a feature extractor and classifier of apple leaf images. CNN was chosen because it can apply learning and classification effective and automated image features than traditional feature extraction methods. The dataset used is Plant Pathology 2020 - FGV C7. In this dataset, it was found that the image size varies greatly from the entire dataset or often referred to as data imbalance. In this study, the oversampling technique was successfully applied to handle the uneven distribution of data (imbalanced) and achieved a good evaluation result. The oversampling approach method used is Synthetic Minority Oversampling Technique (SMOTE). The number of imbalanced images is carried out by SMOTE pre-processing to produce balanced data. The CNN algorithm is trained on training data and performance testing on test data with a ratio of 70:30 of the total data. The learning model on the network structure can achieve an accuracy of 92% with data that has been oversampled. [ABSTRACT FROM AUTHOR]

In the present study three species of syrphid predators were found feeding on green apple aphid on the apple nursery plants. These species are Betasyrphus serarius (Wiedemann), Episyrphus balteatus De Geer, and Metasyrphus confrater (Wiedemann). These syrphid species belonging to Family Syrphidae of order Diptera. Observations were made on Episyrphus balteatus De Geer a syrphid predator of green apple aphid, Aphis pomi De Geer in Shimla Hills of Himachal Pradesh, India. The larval stages of Episyrphus balteatus De Geer, was found to predate upon the green apple aphid, Aphis pomi De Geer which is a serious pest of apple nursery plants in Himachal Pradesh which is the main apple growing state of India. Feeding potential of larval stages of Episyrphus balteatus De Geer was recorded during summer and autumn season. Present studies show that the larvae of this species can effectively control the populations of green apple aphid, Aphis pomi De Geer in the apple orchards and nurseries. [ABSTRACT FROM AUTHOR]

Highlights • A segmentation method of merging after regions extraction for bagged apple image. • Normal-light fruit area oriented extraction based on CLAHE method. • Highlighted fruit area oriented extraction based on image reconstruction. Abstract Based on the own characteristics of bagged green apple image, the work designed an image segmentation method of bagged green apples which was combined after extraction of the normal light regions and highlighted regions of fruits. The contrast limited adaptive histogram equalization (CLAHE) algorithm was deepened fruit green region and improve edge definition in image, and then the R-B color difference image based on CLAHE image was obtained. The linear contrast of the original RGB image was enhanced to improve color difference in the normal light regions of fruits and leaves. The image after contrast enhancement was extracted in the region of R-B color difference image. Then the image was performed with OTSU segmentation algorithm and denoising to extract the normal light region of fruit. For the extraction of highlighted region of fruit in RGB images of bagged green apples, the main colors of image were first extracted. Then, the image was reconstructed with the main colors. The reconstructed and original images were subtracted and denoised to realize the extraction of the highlighted region of fruits. Finally, the complete fruit target region was obtained by combining the two extracted regions. The test results showed that we could obtain more complete fruit region of bagged green fruits based on the method in the work. [ABSTRACT FROM AUTHOR]

Aphid species Aphis pomi (de Geer, 1773) is oligophagous on pomoideous host plants, whilst Aphis spiraecola Patch, 1914 is a polyphagous species alternating between Spiraea spp., its primary host, and a wide variety of secondary hosts, also including pomoideous species. Despite the biological distinction, these species are difficult to separate using their morphological characters. Partial sequences of mitochondrial COI and nuclear EF-1α genes were analyzed for samples from Central and Eastern Europe, Germany, Bulgaria, Italy, Turkey, China together with available data from GenBank. Interspecific pairwise sample divergences of the COI fragment ranged from 3.1 to 4.3%. One COI haplotype of A. pomi was predominant (n = 24), with a pan European distribution. The most abundant COI haplotype of A. spiraecola (n = 16) occurred in Lithuania, Latvia, Poland, Italy, Turkey and China. Interspecific pairwise sample divergences of the EF-1α fragment ranged from 0.6 to 1.2%. Analyzed partial sequences of EF-1α were identical in A. pomi. The most abundant EF-1α haplotype of A. spiraecola (n = 14) occurred in Lithuania, Poland, Italy, Turkey and China. The length of ultimate rostral segment appeared to be the most reliable morphological character for discrimination between apple and spirea aphid species. It allowed a 100% correct identification of A. pomi (n = 143) and 91.5% of A. spiraecola (n = 94) specimens in the European samples used for the molecular analysis. The existence of A. spiraecola in the Eastern Baltic region of Europe is documented for the first time.

Acibenzolar- S -methyl (ASM) is a chemical compound, which is able to induce resistance in several model and non-model plants, but the end-players of this induced defense remain ill-defined. Here, we test the hypothesis that treatment with ASM can protect apple (Malus × domestica) against the rosy apple aphid (Dysaphis plantaginea) and investigate the defense molecules potentially involved in resistance. We measured aphid life traits and performed behavioral assays to study the effect of ASM on plant resistance against the aphid, and then combined transcriptomic, bioinformatics, metabolic and biochemical analyses to identify the plant compounds involved in resistance. Plants treated with ASM negatively affected several life traits of the aphid and modified its feeding and host seeking behaviors. ASM treatment elicited up-regulation of terpene synthase genes in apple and led to the emission of (E,E)-α-farnesene, a sesquiterpene that was repellent to the aphid. Several genes encoding amaranthin-like lectins were also strongly up-regulated upon treatment and the corresponding proteins accumulated in leaves, petioles and stems. Our results link the production of specific apple proteins and metabolites to the antibiosis and antixenosis effects observed against Dysaphis plantaginea , providing insight into the mechanisms underlying ASM-induced herbivore resistance. [ABSTRACT FROM AUTHOR]

Apple leaf blotch has been observed in Nelson and Hawke’s Bay regions of New Zealand over recent years. Fungi from the genus Alternaria were consistently obtained from symptomatic leaf material, and morphological and molecular analysis determined that these isolates belong to the Alternaria arborescens complex. Pathogenicity tests were carried out to determine if these fungi were the causal agents of the observed symptoms. Testing was conducted using both orchard and glasshouse grown apple leaves, but symptoms only occurred on young glasshouse grown leaves and only on some of the inoculated leaves. These results confirm that the A. arborescens complex is causing leaf blotch on apple leaves in New Zealand, but also suggest that the fungus is not an aggressive pathogen and disease development is likely dependent on additional factors like leaf age and physiology, climate or growing conditions. [ABSTRACT FROM AUTHOR]

The phenolic profiles of apple cultivars from the SERIDA Asturian cider apple breeding program, including parents and progenies, were determined by ultrahigh-performance liquid chromatography-diode array detector-electrospray ionization-quadrupole time of flight/mass spectrometer in order to study the relationship between phenols and the resistance of apple tree cultivars to rosy apple aphid (RAA). A pattern recognition technique named partial least square discriminant analysis (PLS-DA) was used to classify apple cultivars based on resistance to RAA, resistant and susceptible, reaching scores with accuracy higher than 97% and 91% respectively. Hydroxycinnamic acids, particularly 4-caffeoylquinic acid (4-CQA) and 4- p -coumaroylquinic acid (4-pCoQA), were identified as the major player in RAA resistance by the PLS-DA model. Indeed, the isomerisation 5-CQA → 4-CQA is favoured in resistant cultivars, whereas the isomerisation 5-pCoQA → 4-pCoQA is favoured in susceptible cultivars. As a result, resistant cultivars accumulate higher amounts of 4-CQA than susceptible ones, and the opposite occurs for 4-pCoQA. Also, minor isomerisations of 5-CQA to 1-CQA or 3-CQA show opposite behaviour for resistant and susceptible cultivars. Cultivar resistance to RAA is concluded to be related with the phenylpropanoid pathway, the isomerisation reactions being the key metabolic reaction for a cultivar to be resistant or susceptible to RAA. [ABSTRACT FROM AUTHOR]

Regulated deficit irrigation, which is a common practice to cope with water scarcity, can impact plant-aphid interactions, and possibly lead to a reduction in the use of pesticides. To test the possible effect of water restriction on the apple tree-rosy apple aphid ( Malus domestica-Dysaphis plantaginea ) system, we performed a factorial experiment with two levels of water supply and two genotypes on artificially infested trees. Plant growth and aphid abundance were characterised during the entire infestation period at two scales of analysis: the apical shoot scale and the tree scale, and additional measures were performed to evaluate plant water status. Aphid abundance increased with plant vegetative growth at both scales of analysis, which is consistent with the Plant Vigor Hypothesis (i.e. with the fact that most of the phloem feeders prefer fast growing plants). At the tree scale, aphid abundance was lower on trees that underwent water restriction, but at the shoot scale, aphid abundance responded differently to water restriction depending on the tree genotype. Water restriction modified the relationship between aphid abundance and growth, thus indicating that host suitability for aphids was affected by different plant variables susceptible to water stress, among which growth. The different response patterns at the two scales of analysis highlight the importance of scale choice in the study of plant-insect interactions. [ABSTRACT FROM AUTHOR]

Biological control agents (BCA) are often mass reared at conditions very different from those at which they have to provide their service, especially if they are to be used under field conditions. It has been suggested that biocontrol efficiency might be enhanced by acclimating the BCA under near-field conditions for some time before release (beneficial acclimation hypothesis), and some studies (e.g. with ladybirds) have supported this idea. We reared Orius majusculus , a commercially available BCA, at three temperatures (12, 16 and 20 °C) throughout the whole development. The predation capacity for rosy apple aphids ( Dysaphis plantaginea ) of females from each of these treatments was tested at the same temperatures (12, 16 and 20 °C). Additionally, we tested the effects of low temperature treatment only during the last nymphal instar, to examine if shorter treatments would have the same effects. Our results rejected the positive acclimation hypothesis. At all test temperatures predation capacity was highest for females that had developed at 20 °C and lowest for those that had developed at 12 °C. Thus, development at low temperatures had a detrimental effect on predatory performance (negative acclimation effect) at both high and low temperatures, and the effect was larger the longer the treatment. Mortality of the nymphs was also increased at lower temperatures. Thus, no enhanced biocontrol efficiency or production benefits were gained from low temperature treatment of O. majusculus , neither as full developmental treatment nor as a short term treatment. [ABSTRACT FROM AUTHOR]

EpisyrphusbalteatusDe Geer (Diptera: Syrphidae) is one of the most efficient biocontrol agents againstDysaphisplantagineaPasserini (Hemiptera: Aphididae) in apple orchards due to its early arrival. However, releasing flying predators in open orchards may be risky. We thus evaluated the combined effects of biological (early release of syrphids) and physical (Alt'Carpo nets) methods for controlling aphids under orchard conditions assuming that syrphids released under the nets will be able to survive and reproduce. Five experimental treatments containing two rows of trees each were set up in a pesticide-free orchard containing two different apple cultivars. For each cultivar,E. Balteatusadults were released (25, 40 and 90 adults per row) into three treatments, which were covered with nets, and two treatments were maintained free as controls (with and without nets). The releases, mainly in treatment 90, had a small effect on the development of the aphid population compared to netted control trees, especially towards the end of the study period when some of the differences were significant. This study demonstrated thatE. balteatusadults can be successfully released under nets since we did observe an accumulation in the offspring of released individuals, mainly in treatments 40 and 90. [ABSTRACT FROM PUBLISHER]

Apple leaf disease is one of the main factors to constrain the apple production and quality. It takes a long time to detect the diseases by using the traditional diagnostic approach, thus farmers often miss the best time to prevent and treat the diseases. Apple leaf disease recognition based on leaf image is an essential research topic in the field of computer vision, where the key task is to find an effective way to represent the diseased leaf images. In this research, based on image processing techniques and pattern recognition methods, an apple leaf disease recognition method was proposed. A color transformation structure for the input RGB (Red, Green and Blue) image was designed firstly and then RGB model was converted to HSI (Hue, Saturation and Intensity), YUV and gray models. The background was removed based on a specific threshold value, and then the disease spot image was segmented with region growing algorithm (RGA). Thirty-eight classifying features of color, texture and shape were extracted from each spot image. To reduce the dimensionality of the feature space and improve the accuracy of the apple leaf disease identification, the most valuable features were selected by combining genetic algorithm (GA) and correlation based feature selection (CFS). Finally, the diseases were recognized by SVM classifier. In the proposed method, the selected feature subset was globally optimum. The experimental results of more than 90% correct identification rate on the apple diseased leaf image database which contains 90 disease images for there kinds of apple leaf diseases, powdery mildew, mosaic and rust, demonstrate that the proposed method is feasible and effective. [ABSTRACT FROM AUTHOR]

Global warming impacts natural communities through effects on performance of individual species and through changes in the strength of interactions between them. While there is a body of evidence of the former, we lack experimental evidence on potential changes in interaction strengths. Knowledge about multispecies interactions is fundamental to understand the regulation of biodiversity and the impact of climate change on communities. This study investigated the effect of warming on a simplified community consisting of three species: rosy apple aphid Dysaphis plantaginea feeding on plantain, Plantago lanceolata, and a heterospecific neighbouring plant species, perennial ryegrass, Lolium perenne. The aphid does not feed on L. perenne. The experimental design consisted of monocultures and mixtures of L. perenne and P. lanceolata at three temperature levels. We did not find indication for indirect temperature effects on D. plantaginea through changes in leaf nitrogen or relative water content. However, experimental warming affected the life history traits of the aphid directly, in a non-linear manner. Aphids performed best at moderate warming, where they grew faster and had a shorter generation time. In spite of the increased population growth of the aphids under warming, the herbivory rates were not changed and consequently the plant-herbivore interaction was not altered under warming. This suggests reduced consumption rates at higher temperature. Also plant competition affected the aphids but through an interaction with temperature. We provide proof-of-concept that net interactions between plants and herbivores should not change under warming despite direct effects of warming on herbivores when plant-plant interaction are considered. Our study stresses the importance of indirect non-trophic interactions as an additional layer of complexity to improve our understanding of how trophic interactions will alter under climate change. [ABSTRACT FROM AUTHOR]

Spiders dwelling in the canopy of apple trees may contribute to the control of the rosy apple aphid ( Dysaphis plantaginea) in spring. They are expected to be very efficient early in the season during aphid colony establishment. However, their predation on aphids may be impaired by insecticide treatments. In the present study, we aimed to assess the effectiveness of spider predation on D. plantaginea in apple orchards. For this purpose, we sampled a total of 1281 canopy spiders in 8 orchards under IPM (Integrated Pest Management), organic or insecticide-free management in the early and mid-season. DNA analyses of the spider guts with specific D. plantaginea PCR primers were performed to estimate which taxa had eaten this aphid pest in the early and mid-season . Lastly, we assessed the effectiveness of aphid suppression by spiders in insecticide-free orchards during these two periods. The most abundant spiders collected belonged to the Philodromidae, Salticidae and Anyphaenidae families. Spiders were more abundant in the insecticide-free orchards than in the other orchards in the mid-season but not in the early season. The positive detection of D. plantaginea DNA was observed in 8 out of the 12 most abundant families and occurred in all orchards. The probability for a spider to be found positive increased with the abundance of aphids and was higher in the insecticide-free than in the other orchards. It did not depend on the spider prosoma size. Lastly, the increase in the number of aphid colonies early in the season was negatively related to the abundance of Philodromus spp. All these results showed that numerous spider taxa participate in the control of D. plantaginea in organic, conventional and IPM orchards and that Philodromus spp. may be particularly efficient in the early season where arthropod communities are not disturbed by insecticides. [ABSTRACT FROM AUTHOR]

Nine species of coccinellids (Coleoptera: Coccinellidae) and three species of syrphid (Diptera: Syrphidae) predators of the green apple aphid, Aphis pomi De Geer, occurring in apple nurseries in Himachal Pradesh are reported. The coccinellids included Cheilomenes sexmaculata (F.), Coccinella septempunctata (L.), Coccinella transversalis F., Coelophora bissellata (Mulsant), Coelophora saucia (Mulsant), Harmonia dimidiata (F.), Hippodamia variegata (Goeze), Oenopia sauzeti (Mulsant) and Priscibrumus uropygialis (Mulsant), while the syrphids included Betasyrphus serarius (Wiedemann), Episyrphus balteatus De Geer and Metasyrphus confrater (Wiedemann). Of the coccinellids, C. sexmaculata, C. bissellata, C. saucia and H. dimidiata were found to be more effective for the natural suppression of A. pomi in apple nurseries in the state. [ABSTRACT FROM AUTHOR]

Aphis pomi De Geer, the green apple aphid, is an economic pest of apple and other rosaceae throughout the world. In the present study, functional responses of the syrphids Episyrphus balteatus De Geer, Eristalis tenax (L.), Eristalis interruptus (Poda), and Sphaerophoria scripta (L.), to A. pomi were studied under laboratory conditions to determine their relative predatory potential. The second- and third-instar larvae of the predators were exposed to increasing densities of similar-sized A. pomi nymphs in Petri dishes. Ep. balteatus was found to possess the highest consumption rate followed by Er. tenax, Er. interruptus, and S. scripta. All predator species and stages exhibited a Type II functional response. The coefficients of attack rate and handling time showed an insignificant variation between species and preying stages, suggesting equal potential of the four syrphid species to regulate A. pomi colonies. [ABSTRACT FROM AUTHOR]

Apple orchardists are encouraged to adopt pest control strategies with less pesticide use and thus less harmful environmental impacts. In this study, we compared the possible effects of organic, integrated pest management (IPM), and conventional protection strategies on the rosy apple aphid-ant-natural enemy communities in 12 apple orchards in south-eastern France in 2008 and 2009. The organic orchards had the smallest aphid populations and the most diverse and abundant natural enemy populations compared with the other orchards. More diverse and abundant natural enemy populations were observed in IPM compared with conventional orchards. In 2009, the aphid abundance in IPM orchards was, however, significantly higher than in conventional orchards. No significant differences in ant densities were observed among protection strategies in 2008, but in 2009, these densities were significantly higher in conventional compared with organic orchards. Three predator groups were the most common: Coccinellidae, Forficulidae, and Syrphidae. These were significantly more abundant in organic orchards than in the other orchards, except in 2008 when there was no significant difference in syrphid and earwig abundance between organic and IPM orchards. Parasitoids were significantly more abundant in organic orchards in 2009 but not in 2008. The smaller number of aphids in organic orchards appears to results from the absence of toxic insecticides and thus to increased natural enemies compared with other orchards. Our findings emphasize the importance of no or less intensive synthetic pesticide usage for the conservation of natural enemies biodiversity and biological control of rosy apple aphid in apple orchards. [ABSTRACT FROM AUTHOR]

This paper presents data referring to the external morphological characteristics, the biometrical measurements and the life cycle of Aphis pomi. The researches have been carried out on the orchards from the experimental fields of the Didactic Station Timiş oara (Timiş County) and Várfurile, (Arad County), 2003 2008. At the Aphis pomi species the smallest length of the body established for aphids captured in the western zone of Romania was 1.80 mm, while the biggest was 2.00 mm. Regarding the length of the head and thorax, it may be noticed that the maximum length of these parts was 1 mm, and the minimum length was 0.65 mm. The minimum width of the head was 0.20 mm and the maximum width of the head was 0.35 mm. The thorax width had a minimum of 0.60 mm and a maximum of 0.80 mm. The minimum length of the abdomen was 0.90 mm and the minimum width was 0.70 mm, the maximum length of the abdomen was 1.20 mm and the maximum width was 0.90 mm. In the climatic conditions of Romania, Aphis pomi winters in the stage of egg in October usually on the stems of apple tree. In the second decade of March, the eggs hatch out and there appears the fundatrix giving birth to one or more generations of fundatrices, which are apterous parthenogenetic viviparous females. The winged aphid migrates to other nearby host plants like pear, peach trees and other herbaceous plants growing in the vicinity of apple trees. The reproductive process continues rapidly, the populations of aphids are developing quickly in a very short time. Green apple aphids usually remain on apple plants throughout the summer and gave birth parthenogenetically to 9 12 generations. In October, Gynetypes (gynopara) give birth to wingless sexual, oviparous females, that mate with males and lay winter eggs. [ABSTRACT FROM AUTHOR]

Aphid species Aphis pomi (de Geer, 1773) is oligophagous on pomoideous host plants, whilst Aphis spiraecola Patch, 1914 is a polyphagous species alternating between Spiraea spp., its primary host, and a wide variety of secondary hosts, also including pomoideous species. Despite the biological distinction, these species are difficult to separate using their morphological characters. Partial sequences of mitochondrial COI and nuclear EF-1α genes were analyzed for samples from Central and Eastern Europe, Germany, Bulgaria, Italy, Turkey, China together with available data from GenBank. Interspecific pairwise sample divergences of the COI fragment ranged from 3.1 to 4.3%. One COI haplotype of A. pomi was predominant (n = 24), with a pan European distribution. The most abundant COI haplotype of A. spiraecola (n = 16) occurred in Lithuania, Latvia, Poland, Italy, Turkey and China. Interspecific pairwise sample divergences of the EF-1α fragment ranged from 0.6 to 1.2%. Analyzed partial sequences of EF-1α were identical in A. pomi. The most abundant EF-1α haplotype of A. spiraecola (n = 14) occurred in Lithuania, Poland, Italy, Turkey and China. The length of ultimate rostral segment appeared to be the most reliable morphological character for discrimination between apple and spirea aphid species. It allowed a 100% correct identification of A. pomi (n = 143) and 91.5% of A. spiraecola (n = 94) specimens in the European samples used for the molecular analysis. The existence of A. spiraecola in the Eastern Baltic region of Europe is documented for the first time. [ABSTRACT FROM AUTHOR]

Insect chitinase plays essential roles in chitin catabolism involved in digestion and molting during insect development. In the current work, we cloned a chitinase cDNA, LrCht5, from the apple leaf miner moth Lithocolletis ringoniella and characterized its amino acid sequence and protein properties. The L. ringoniella chitinase cDNA was 2136 bp in length with an open reading frame of 1737 bp that encodes a polypeptide of 579 amino acid residues with a predicted molecular mass of 64.4 kDa and p I of 5.49. The catalytic domain has several phosphorylation and glycosylation sites. The recombinant LrCht5 was expressed in Escherichia coli and the Spodoptera frugiperda cell line Sf9, and the LrCht5 expressed in insect cells exhibited chitinolytic activity. LrCht5 was most stable at pH 6.0 and 45°C. This work has potential application in the development of novel and more specific synthetic chitinase inhibitors for use as bioinsecticides. [ABSTRACT FROM AUTHOR]

A multilateral approach that includes both biotic and climatic data was developed to detect the main variables that affect the ecology and population dynamics of woolly apple aphid Eriosoma lanigerum (Hausmann). Crawlers migrated up and down the trunk mainly from spring to autumn and horizontal migration through the canopy was observed from May to August. Winter temperatures did not kill the canopy colonies, and both canopy and root colonies are the source of reinfestations in Mediterranean areas. Thus, control measures should simultaneously address roots and canopy. European earwigs Forficula auricularia (Linnaeus) were found to reduce the survival of overwintering canopy colonies up to June, and this can allow their later control by the parasitoid Aphelinus mali (Haldeman) from summer to fall. Preliminary models to predict canopy infestations were developed. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Fruit load affected seasonal and daily water use efficiency (WUE) of apple trees. [•] Apple WUE was negatively correlated with leaf ash and leaf 13C discrimination. [•] Leaf 13C discrimination was useful in assessing WUE in apple. [•] Apple leaf ash is useful in identifying WUE extremes at a lower cost. [ABSTRACT FROM AUTHOR]

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Aphids are major pests in apple orchards, debilitating the crop and spreading disease. We investigated whether early-season predation by canopy spiders may be effectively controlling aphid numbers in three organic orchards. For this purpose, we monitored the aphid population dynamics from the winter eggs to colony stages and compared this to spider abundances and rates of predation on aphids detected by diagnostic polymerase chain reaction. For the latter, we applied existing general aphid primers. We found that spiders ate colony fundatrices and that aphid numbers were negatively related to spider abundance. Spiders were the main active predators within the orchards when the first colony fundatrices were present, indicating their importance in the early control of aphid populations. [ABSTRACT FROM PUBLISHER]

Chemical characteristics of normal, woolly apple aphid-damaged, and mechanically damaged twigs of six apple cultivars: Red Fuji, Golden Delicious, Qinguan, Zhaojinl08, Starkrimson, and Red General, were examined in autumn wood to provide a better understanding of factors related to cultivar resistance to the woolly apple aphid, Eriosoma lanigerum (Hausmann). Chemical measures examined included soluble sugars, soluble proteins and amino acids, total phenolics, and polyphenol oxidase (that enhances the resistance of plants to insects) and superoxide dismutase, peroxidase, and catalase (that degrade waste products in plants). Soluble sugar, protein, and amino acid contents in normal (undamaged) twigs of Red Fuji, aphid-susceptible cultivar, were higher than in mechanically damaged and aphid-damaged twigs. Total phenolic compounds, an important group of defensive compounds against aphids, increased by 30.5 and 6.0% in mechanically damaged twigs of Qinguan and Zhaojinl08, respectively, and decreased by 21.7 and 16.1% in aphid-damaged twigs of Red Fuji and Red General, respectively. Compared with normal twigs, in aphid-damaged twigs, superoxide dis-mutase, peroxidase, and polyphenol activity all decreased in Red Fuji. The resistance of some apple cultivars to woolly apple aphid during the growth of autumn shoots was related to several of the physiological indices we monitored. The thin epidermis of callus tissue over healed wounds showed increased susceptibility to the attack by woolly apple aphid. Apple cultivar Qinguan with the highest level of resistance to woolly apple aphid in autumn had increased in amino acid, total phenolic compound levels, and enzyme activity after aphid feeding. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Population densities of highly aggregated insect species in complex and variable habitats can be difficult to estimate efficiently, accurately, and with minimal variance. Aphis pomi DeGeer exemplifies this situation, in that its infestations typically are found near the tips of vigorously growing shoots of apple, Mains domestica Borkh, which vary in number and distribution throughout the growing season. Because A. pomi populations are permanently confined to vigorous shoots, randomly selecting shoots to sample is inefficient and unnecessarily increases the variance in population estimates. Previous workers resolved many difficulties in sampling A. pomi by recommending the use of the number of aphids on the most infested leaf as a reliable predictor for the number of aphids on the shoot. While this sampling protocol has been widely adopted, it is most applicable early in the growing season or in other unusual situations when tree vigor is high and randomly selected shoots are likely to be infested. In this paper, we confirm that the most infested leaf is still a reliable predictor for the number of aphids on a shoot throughout the growing season, even when A. pomi densities are very low. However, we also suggest that the efficiency and performance of the most infested leaf as a predictor can be improved by using preliminary sampling to determine the proportion of vigorous shoots in the orchard or block of interest and sampling for A. pomi only from those vigorous shoots. [ABSTRACT FROM AUTHOR]