Aphid Infestation Research Articles

Biochemical probing of phloem sap defensive traits in Brassica juncea-B. fruticulosa introgression lines following Lipaphis erysimi infestation.

The lack of resistance to Lipaphis erysimi in cultivated Brassicas makes caused this pest highly devastating resulting in significant loss of rapeseed-mustard productivity in India. B. fruticulosa, a wild crucifer is known as an excellent source of resistance to L. erysimi. Therefore, we planned to assess defense associated biochemical alterations and molecular components of B. juncea-B. fruticulosa ILs to mustard aphid. Phenotypic assessment of ILs on the basis of aphid population per plant (APP) categorized genotypes into resistant (7.15-18.50 APP), moderately susceptible (42.29-53.33 APP) and susceptible (70.00-77.07 APP) genotypes. Mustard aphid infested minimally B. fruticulosa (0.80 APP) among tested genotypes. The maximum increase in catalase (CAT) activity was determined in B. fruticulosa and resistant ILs after 48h (2.03 and 1.76-fold, respectively) and one week (2.98 and 1.79-fold, respectively) of mustard aphid infestation. The strong induction of CAT2 transcripts (19.25-fold) and CAT activity (5.88-fold) along with low aphid count in resistant IL, Ad4-64 (13.85 APP) suggested the pivotal role of CAT in resistance to mustard aphid. Guaiacol peroxidase (GPX) was significantly decreased following pest infestation at both infestation stages. The ascorbate content was highest in resistant IL, ADV-6RD (2.14-fold) after one week of aphid infestation. H2O2 content rapidly increased in B. juncea-B. fruticulosa derived lines after 48h of aphid infestation. The negative and significant association between APP and CAT (- 0.56** and - 0.48*, respectively), glutathione (- 0.43* and - 0.40*, respectively), H2O2 (- 0.57** and - 0.43*, respectively) at both 48h and one week infestation stages signified their role in deterring mustard aphid infestation. The positive and significant association between total sugars (0.33* at 7 DPI), reducing sugars (0.33* at 7 DPI), sucrose (0.36** at 48h) and APP indicated that higher the sugars content, higher will be mustard aphid infestation in B. juncea derived ILs. The information being generated and key candidates (CAT2, ascorbate and H2O2) being identified may help in effective deployment of B. fruticulosa resistance in mustard breeding.

Genetic Studies for some Bean Traits in Relation to Stability and Insect Infestations

This research was carried out at a private farm located at Qaha, Qalyubia Governorate, Egypt during the two successive summer seasons of 2018 and 2019 to estimate the stability parameters of ten dry bean (Phaseolus vulgaris L.) genotypes for yield, insect infestation and some economic traits under different planting densities as well as to assess the annual variation of some insect pests through different growing densities and seasons in relation to certain climatic factors, synchronization of plant age with insect infestation percentage on plant due to insect activity. There were significant genotype × densities interactions for the studied bean’s traits, i.e., number of days to flowering, pod length, 100-seeds weight, number of pods/plant, yield/feddan and insect infestation. Combined analysis of variance revealed significant differences among genotypes for all studied traits. Pooled deviation mean squares for number of days to flowering, yield/fed. and insect infestation were not significant suggesting the consistency of the genotypes yielding ability under environmental conditions tested. The high yielding genotypes G6, G1 and G10 produced high yielding performance based on wide adaptation and stability of performance over all environments. Genotypes G3, G5, G7 and G10 were insensitive to environmental changes and could be recommended for cultivation under all conditions. Genotype G8 also had minimum aphid infestation over range of environments showed below regression coefficients for yield/fed. and insect infestation and low deviation from regression, indicated specific adaptability of this genotype to unfavorable environments. Genetic variation (σ2g) was large in magnitude compared to error one (σ2e) in all studied traits of all cases except pod length in all densities of 2nd season (Env. 5-8) and number of pods under 10 cm/2 rows of Env.8, reflecting the genetic differences among genotypes for all studied traits except of those two cases. The population of both leaf miners (Melanogromyza phaseoli) and aphid (Aphis craccivora Koch) was observed from the third week of March (5th week after planting date) and continued till to 3rd week of May (14th week after planting) and reached to a peak level 55.2 and 85.9% for aphid and leaf miners during 9th and 11th weeks after planting date, respectively, i.e. 2nd and 4th week of April. Genotype G8 interacted with planting space of (5 cm ×2 rows) were explained the lowest Melanagromyza phaseoli (Tryon) and Aphis craccivora Koch, infestations (18.8% and 12.6%, respectively) followed by G1 and G5 with the same planting space for leaf miners (29.6%) and aphid (15.3%) infestations, respectively.

Patchiness caused by aphid herbivory and ozone events affects aphid's spread

AbstractAphids exploit different patches that offer a favourable habitat during their life cycle. Continuous colonization of new patches is critical for the survival of these insect pests. We developed a mesocosm experimental system to study the effects of stress regimes on the colonization of plants by aphids. In the first experiment, we treated Eruca sativa Mill (arugula) plants with either low ozone (O3) (ambient air with no O3 added), elevated O3 (ambient air with O3 addition) or low O3 + Myzus persicae aphid feeding, with subsequent observation of natural aphid infestation over time. The second experiment consisted of aphid sources and differently treated aphid sinks. The aphid sources were also exposed to either low or high O3 levels. The colonization of the sinks was then monitored over time and distance from source. The infestation rate was increased if the patches had been recently exposed to aphid herbivory. On the contrary, aphids did not colonize patches that experienced a recent O3 episode. The patches of E. sativa plants without prior biotic or abiotic stress were colonized by aphids at the beginning of the experiment, but infestation was poor and most of the plants remained aphid‐free throughout the experiment. Aphids from control patches had a better chance of successfully disseminate on hosts with previous herbivory, and aphid spread from O3‐stressed plants was generally poor. Hence, the colonization risk for a generalist aphid plague will depend on the space–time arrangement between crop patches with different stress levels. Ozone contamination could have a negative effect on the spread infestation of aphids in annual crops, because of habitat fragmentation. Here, we present important information to understand how physiological traits of individuals can be scaled up to predict changes within populations in a scenario of climate change.

The Efficacy of Selected Insecticides Against Wheat Aphids on Irrigated Wheat in North Western Amhara, Ethiopia

Aphid infestations cause significant losses in wheat production. The experiment was conducted at the Koga irrigation site during 2021 to evaluate the efficacy of commercial insecticides for the management of wheat aphids. Seven types of insecticides with unsprayed control were laid in a completely randomized block design with three replications. The result showed a reduced aphid infestation with maximum grain yield were from dimethoate, imidacloprid, lambda-cyhalotrin, profenfos + lambda-cyhalothrin, imidacloprid + lambda-cyhalothrin, and profenofos-sprayed plots. However, the greater net benefit and marginal rate of return were provided by the applications of imidacloprid and dimethoate insecticides. The economically feasible insecticide application can be considered as an effective aphid management practice in wheat production.

The Influence of Lead and Acyrthosiphon pisum (Harris) on Generation of Pisum sativum Defense Signaling Molecules and Expression of Genes Involved in Their Biosynthesis.

The main aim of this study was to understand the regulation of the biosynthesis of phytohormones as signaling molecules in the defense mechanisms of pea seedlings during the application of abiotic and biotic stress factors. It was important to identify this regulation at the molecular level in Pisum sativum L. seedlings under the influence of various concentrations of lead-i.e., a low concentration increasing plant metabolism, causing a hormetic effect, and a high dose causing a sublethal effect-and during feeding of a phytophagous insect with a piercing-sucking mouthpart-i.e., pea aphid (Acyrthosiphon pisum (Harris)). The aim of the study was to determine the expression level of genes encoding enzymes of the biosynthesis of signaling molecules such as phytohormones-i.e., jasmonates (JA/MeJA), ethylene (ET) and abscisic acid (ABA). Real-time qPCR was applied to analyze the expression of genes encoding enzymes involved in the regulation of the biosynthesis of JA/MeJA (lipoxygenase 1 (LOX1), lipoxygenase 2 (LOX2), 12-oxophytodienoate reductase 1 (OPR1) and jasmonic acid-amido synthetase (JAR1)), ET (1-aminocyclopropane-1-carboxylate synthase 3 (ACS3)) and ABA (9-cis-epoxycarotenoid dioxygenase (NCED) and aldehyde oxidase 1 (AO1)). In response to the abovementioned stress factors-i.e., abiotic and biotic stressors acting independently or simultaneously-the expression of the LOX1, LOX2, OPR1, JAR1, ACS3, NCED and AO1 genes at both sublethal and hormetic doses increased. Particularly high levels of the relative expression of the tested genes in pea seedlings growing at sublethal doses of lead and colonized by A. pisum compared to the control were noticeable. A hormetic dose of lead induced high expression levels of the JAR1, OPR1 and ACS3 genes, especially in leaves. Moreover, an increase in the concentration of phytohormones such as jasmonates (JA and MeJA) and aminococyclopropane-1-carboxylic acid (ACC)-ethylene (ET) precursor was observed. The results of this study indicate that the response of pea seedlings to lead and A. pisum aphid infestation differed greatly at both the gene expression and metabolic levels. The intensity of these defense responses depended on the organ, the metal dose and direct contact of the stress factor with the organ.

POTENTIAL IMPACT OF NITROGEN ON POPULATION FLUCTUATION OF APHID AND YIELD PARAMETERS IN BARLEY

The present study was carried out on the farmer field under the supervision of the Department of Plant Protection and Quality Control of Pesticides during 2020 and 2021. Barley cultivar ‘Haider-93’ was sown in a randomized complete block design (RCBD) with three replications to examine the effect of two levels ofnitrogen fertilizer, 50 and 100 kg/ha along with control (no fertilizer), on population fluctuation of aphid and on barley yield components like grain protein (%), 1000-grain weight and the barley grain yield. Aphid incidence was recorded throughout the cropping season. The results revealed that peak infestation of aphids per tiller were recorded in the 3rd week of February in successive year. The study indicated a significant relationship between nitrogen fertilizer and aphid population density per tiller. The mean aphid population per tiller was recorded a significantly higher (34.12 ± 0.81 and 28.65 ± 0.17 for the years 2020 and 2021, respectively) at 100 kg/ha of nitrogen level while lowest infestation (14.51 ± 0.20 and 12.30 ± 0.10 aphids per tiller for the year 2020 and 2021, respectively) was recorded at 0 kg/ha of nitrogen fertilizer. Nitrogen fertilizer level at 100 kg/ha gave significantly higher grain protein (12.80 ± 0.17 and 13.70 ± 0.26% for the years 2020 and 2021, respectively) and grain yield (2758.75 ± 60.82 and 2673.79 ± 61.88 kg/ha produce for the year 2020 and 2021, respectively) of the barley crop. However, treatment differences for 1000-grain weight (g) were recorded as non-significant. These findings suggest that the nitrogen fertilizer at 100 kg/ha level produced significantly higher grain protein (%) and grain yield at the same time, also supported the higher infestation of aphids per tiller. Still, this aphid density did not affect the accumulation of grain protein (%) and grain yield of the barley crop. The results of this study might be used for decision-making to apply nitrogen fertilizer for better grain yield of barley crop but at the same time considering the colonizing aphid population.

A review on molecular aspects of virus-vector relationship to the aphids

Plant viruses are transmitted through insects, mites, nematodes, and protists. Arthropods as vectors are used by 88% of plant viruses to move from one host to another. Insects are the most prevalent vectors, with aphids accounting for half of all insect-vectored viruses. Aphids have been meticulously developed to serve as vectors. Transforming virions into plant cells is facilitated bypiercing–sucking mouthparts that do not cause irreversible damage. With the ability to reproduce asexually, aphid populations can grow incredibly, amplifying disease epidemics and accelerating the spread of viruses over short and vast distances. Aphids significantly reduce crop productivity by spreading numerous plant viruses. Being obligate intracellular pathogens, viruses rely heavily on vectors to spread and survive. Aphids are responsible for the majority of economically significant plant virus transmission and cause heavy crop loss worldwide. Aphids feed on the plant as insect pathogens and carry plant pathogens such as Viruses. Either persistent circulation, non-circulation or not persistently, they spread viruses. The process of plant virus transmission by insects has changed over time and is significantly impacted by the biology and morphology of insects. Much research during the last century has offered an in-depth understanding of the molecular mechanisms underpinning virus-vector interactions. The present review discusses the molecular interaction of the virus–vector relationship by Aphids. This will provide a clue to the scientific community to successfully combat aphid infestation in agriculture.

Computer vision model for sorghum aphid detection using deep learning

Aphids are a challenging crop pest to manage. The sorghum aphid, for example, causes considerable yield loss in unmanaged sorghum. One of the key strategies to mitigate yield losses caused by this pest includes monitoring productions fields and using economic thresholds to spray insecticides. However, monitoring aphids is a time-consuming task and requires regular, visual assessments across large hectarage once aphids are detected on sorghum plants. To address this challenge, we propose to use object detection models based on deep learning to automatically detect aphid infestations on sorghum leaves using digital images. We used 1190 images collected during field monitoring events and evaluated the performance of 3 deep learning detection models within the YOLOv5 family that vary in complexity: YOLOv5n, YOLOv5s, and YOLOv5m. We then tested three different image sizes, including input resolutions of 416 × 416, 640 × 640, and 1280 × 1280 pixels. We trained models to detect individual aphids, which ranged between 1 and 125 sorghum aphids/leaf and is comparable to threshold levels used to manage aphids in field conditions (i.e., 50–125 aphids per leaf). Detection models had a precision of 92% precision with a 84.5% recall and 90.6% mAP@0.5 for YOLOv5m Pytorch, making it a potential candidate for quantifying aphid densities using deep learning. The models tested and methodology developed here can be implemented in management decisions of sorghum aphids or as sampling tools for use in screening insect-resistant varieties. Development of mobile applications and integration into unmanned vehicles with sophisticated sensor systems will aid in use and adoption of computer vision models for pest management.

Occurrence of Aphid, <i>Aphis gossypii</i> Glover and Coccinellids on Isabgol

Aphid Aphis gossypii Glover was found to be the major pest of isabgol in the semi-arid regions of the Rajasthan. The infestation of aphid initiated from 2nd standard meteorological week (SMW) with 6 aphids/ plant and fluctuated till 13th SMW. The peak activity of aphids observed on 8th SMW which gradually reached to the level of 56.13 aphids/ plant and thereafter gradually decreased up to 7.87 aphids/plant in the fourth week of March when the crop matured. The activities of three coccinellid beetles viz. Brumoides suturalis Fabricius, Cheilomenes sexmaculata Fabricius and Coccinella septempunctata Fabricius were also studied, and their peak population was noticed from 8th to 10th SMW (19th February to 5th March, 2022). The significant positive correlation of aphid population was found with bright sunshine and all three species of coccinellids. C. sexmaculata and C. septempunctata have the significant positive correlation with bright sunshine, maximum temperature and average temperature while negative non-significant correlation with relative humidity.

Importin β1 Mediates Nuclear Entry of EIN2C to Confer the Phloem-Based Defense against Aphids.

Ethylene Insensitive 2 (EIN2) is an integral membrane protein that regulates ethylene signaling towards plant development and immunity by release of its carboxy-terminal functional portion (EIN2C) into the nucleus. The present study elucidates that the nuclear trafficking of EIN2C is induced by importin β1, which triggers the phloem-based defense (PBD) against aphid infestations in Arabidopsis. In plants, IMPβ1 interacts with EIN2C to facilitate EIN2C trafficking into the nucleus, either by ethylene treatment or by green peach aphid infestation, to confer EIN2-dependent PBD responses, which, in turn, impede the phloem-feeding activity and massive infestation by the aphid. In Arabidopsis, moreover, constitutively expressed EIN2C can complement the impβ1 mutant regarding EIN2C localization to the plant nucleus and the subsequent PBD development in the concomitant presence of IMPβ1 and ethylene. As a result, the phloem-feeding activity and massive infestation by green peach aphid were highly inhibited, indicating the potential value of EIN2C in protecting plants from insect attacks.

Aphid adaptation to cucurbits: sugars, cucurbitacin and phloem structure in resistant and susceptible melons

BackgroundAphis gossypii, a strictly phloemophagaous aphid, colonize hundreds of plant families, and a group of clones formed a cucurbit-specialised host-race. Cucurbits are unique in having evolved a specific extra-fascicular phloem (EFP), which carries defence-related metabolites such as cucurbitacin, whereas the fascicular phloem (FP) is common to all higher plants and carries primary metabolites, such as raffinose-family oligosaccharides (RFOs). Both cucurbitacins (in the EFP) and galactinol (in the FP) have been suggested to be toxic to aphids. We investigated these hypotheses in cucurbit-specialized A. gossypii fed on melon plants with or without aphid-resistance conferred by the NLR gene Vat. We selected a plant-aphid system with (i) Vat-mediated resistance not triggered, (ii) Vat-mediated resistance triggered by an aphid clone adapted to the presence of Vat resistant alleles and (iii) Vat-mediated resistance triggered by a non-adapted aphid clone.ResultsWe quantified cucurbitacin B, its glycosylated derivative, and sugars, in melon plants and aphids that fed on. The level of cucurbitacin in plants was unrelated to both aphid infestation and aphid resistance. Galactinol was present at higher quantities in plants when Vat-mediated resistance was triggered, but its presence did not correlate with aphid performance. Finally, we showed that cucurbit-specialized A. gossypii fed from the FP but could also occasionally access the EFP without sustainably feeding from it. However, the clone not adapted to Vat-mediated resistance were less able to access the FP when the Vat resistance was triggered.ConclusionWe concluded that galactinol accumulation in resistant plants does not affect aphids, but may play a role in aphid adaptation to fasting and that Cucurbitacin in planta is not a real threat to Aphis gossypii. Moreover, the specific phloem of Cucurbits is involved neither in A. gossypii cucurbit specialisation nor in adaptation to Vat-dependent resistance.

Chalcone synthase (CHS) family genes regulate the growth and response of cucumber (Cucumis sativus L.) to Botrytis cinerea and abiotic stresses

The chalcone synthase (CHS) gene family is instrumental not only regulating plant growth and development but fine-tuning plant response to environmental hazards. Despite the growing body of literature, the role of CHS genes in cucumber (Cucumis sativus L.) remains elusive. Herein, we identified 4 CsCHS genes from the cucumber genome database. The evolutionary relationship, gene structure, conserved motifs, proteins interaction and chemical properties highlight the key aspects of CsCHS genes in cucumbers. Evolutionary tree analysis reveals that the CsCHS family is divided into four clades. Moreover, the Gene Ontology (GO) analysis showed that CsCHS genes regulate plant growth and response to various environmental stimuli. Microarray expression data showed that CsCHS genes were expressed in almost all the tested tissues. Additionally, the differential expression patterns of the CsCHS genes were found under salinity stress and hormonal treatments. The qRT-PCR analysis of CsCHS genes under aphid infestation revealed they are key components of plant defense against insect pests. Under waterlogging stress, only the CsCHS3 displayed high expression under naphthalene acetic acid (NAA) and ethylene (ETH). The dual luciferase assay indicated that CsCHS2 effectively binds to the promoters of key stress markers CsERF1 and CsERF3. Our results have provided detailed knowledge regarding the CsCHS gene's influential role in growth and development and also providing the resistive defense in cucumber plants. We believe our study will facilitate the breeding of stress-resilient cultivars, particularly against insect pests and waterlogging stress.

Arbuscular mycorrhizal fungus changes alfalfa (Medicago sativa) metabolites in response to leaf spot (Phoma medicaginis) infection, with subsequent effects on pea aphid (Acyrthosiphon pisum) behavior.

Plant disease occurs simultaneously with insect attack. Arbuscular mycorrhizal fungi (AMF) modify plant biotic stress response. Arbuscular mycorrhizal fungi and pathogens may modify plant volatile organic compound (VOC) production and insect behavior. Nevertheless, such effects are rarely studied, particularly for mesocosms where component organisms interact with each other. Plant-mediated effects of leaf pathogen (Phoma medicaginis) infection on aphid (Acyrthosiphon pisum) infestation, and role of AMF (Rhizophagus intraradices) in modifying these interactions were elucidated in a glasshouse experiment. We evaluated alfalfa disease occurrence, photosynthesis, phytohormones, trypsin inhibitor (TI) and total phenol response to pathogen and aphid attack, with or without AMF, and aphid behavior towards VOCs from AMF inoculated and non-mycorrhizal alfalfa, with or without pathogen infection. AM fungus enhanced alfalfa resistance to pathogen and aphid infestation. Plant biomass, root : shoot ratio, net photosynthetic rate, transpiration rate, stomatal conductance, salicylic acid, and TI were significantly increased in AM-inoculated alfalfa. Arbuscular mycorrhizal fungi and pathogen significantly changed alfalfa VOCs. Aphids preferred VOCs of AM-inoculated and nonpathogen-infected to nonmycorrhizal and pathogen-infected alfalfa. We propose that AMF alter plant response to multiple biotic stresses in ways both beneficial and harmful to the plant host, providing a basis for strategies to manage pathogens and herbivore pests.

Detection of Aphids on Hyperspectral Images Using One-Class SVM and Laplacian of Gaussians

Aphids cause severe damage to agricultural crops, resulting in significant economic losses, and an increased use of pesticides with decreased efficiency. Monitoring aphid infestations through regular field surveys is time-consuming and does not always provide an accurate spatiotemporal representation of the distribution of pests. Therefore, an automated, non-destructive method to detect and evaluate aphid infestation would be beneficial for targeted treatments. In this study, we present a machine learning model to identify and quantify aphids, localizing their spatial distribution over leaves, using a One-Class Support Vector Machine and Laplacian of Gaussians blob detection. To train this model, we built the first large database of aphids’ hyperspectral images, which were captured in a controlled laboratory environment. This database contains more than 160 images of three aphid lines, distinctive in color, shape, and developmental stages, and are displayed laying on leaves or neutral backgrounds. This system exhibits high-quality validation scores, with a Precision of 0.97, a Recall of 0.91, an F1 score of 0.94, and an AUPR score of 0.98. Moreover, when assessing this method on new and challenging images, we did not observe any false negatives (and only a few false positives). Our results suggest that a machine learning model of this caliber could be a promising tool to detect aphids for targeted treatments in the field.

Combining quantitative trait locus mapping with multiomics profiling reveals genetic control of corn leaf aphid (Rhopalosiphum maidis) resistance in maize.

The corn leaf aphid (Rhopalosiphum maidis) is a major maize pest that frequently causes substantial yield losses. Exploring the genetic basis of resistance to aphids is important for improving maize yield and quality. Here, we used a maize recombinant inbred line population derived from two parents with different susceptibility to aphids, B73 (susceptible) and Abe2 (resistant), and performed quantitative trait locus (QTL) mapping using aphid resistance scores as an indicator. We mapped a stable QTL, qRTA6, to chromosome 6 using data from 2 years of field trials, which explained 40.12-55.17% of the phenotypic variation. To further investigate the mechanism of aphid resistance in Abe2, we constructed transcriptome and metabolome libraries from Abe2 and B73 leaves with or without aphid infestation at different time points. Integrating QTL mapping and transcriptome data revealed three aphid resistance candidate genes (Zm00001d035736, Zm00001d035751, and Zm00001d035767) associated with the hypersensitive response, the jasmonic acid pathway, and protein ubiquitination. Integrated transcriptomic and metabolomic analysis revealed that the differentially expressed genes and metabolites were enriched in flavonoid biosynthesis. These findings extend our understanding of the molecular mechanisms controlling aphid resistance in maize, and the QTL and candidate genes are valuable resources for increasing this resistance.

Genome-wide identification and characterization of lipoxygenase genes related to the English grain aphid infestation response in wheat.

44 wheat LOX genes were identified by silico genome-wide search method. TaLOX5, 7, 10, 24, 29, 33 were specifically expressed post aphid infestation, indicating their participation in wheat-aphid interaction. In plants, LOX genes play important roles in various biological progresses including seed germination, tuber development, plant vegetative growth and most crucially in plant signal transduction, stress response and plant defense against plant diseases and insects. Although LOX genes have been characterized in many species, the importance of the LOX family in wheat has still not been well understood, hampering further improvement of wheat under stress conditions. Here, we identified 44 LOX genes (TaLOXs) in the whole wheat genome and classified intothree subfamilies (9-LOXs, Type I 13-LOXs and Type II 13-LOXs) according to phylogenetic relationships. The TaLOXs belonging to the same subgroup shared similar gene structures and motif organizations. Synteny analysis demonstrated that segmental duplication events mainly contributed to the expansion of the LOX gene family in wheat. The results of protein-protein interaction network (PPI) and miRNA-TaLOXs predictions revealed that three TaLOXs (TaLOX20, 22 and 37) interacted mostly with proteins related to methyl jasmonate (MeJA) signaling pathway. The expression patterns of TaLOXs in different tissues (root, stem, leaf, spike and grain) under diverse abiotic stresses (heat, cold, drought, drought and heat combined treatment, and salt) as well as under diverse biotic stresses (powdery mildew pathogen, Fusarium graminearum and stripe rust pathogen) were systematically analyzed using RNA-seq data. We obtained aphid-responsive candidate genes by RNA-seq data of wheat after the English grain aphid infestation. Aphid-responsive candidate genes, including TaLOX5, 7, 10, 24, 29 and 33, were up-regulated in the wheat aphid-resistant genotype (Lunxuan144), while they were little expressed in the susceptible genotype (Jimai22) during late response (48h and 72h) to the English grain aphid infestation. Meanwhile, qRT-PCR analysis was used to validate these aphid-responsive candidate genes. The genetic divergence and diversity of all the TaLOXs in bread wheat and its relative species were investigated by available resequencing data. Finally, the 3D structure of the TaLOX proteins was predicted based on the homology modeling method. This study not only systematically investigated the characteristics and evolutionary relationships of TaLOXs, but also provided potential candidate genes in response to the English grain aphid infestation and laid the foundation to further study the regulatory roles in the English grain aphid infestation of LOX family in wheat and beyond.

Effects of wheat undersowing and sweet alyssum intercropping on aphid and flea beetle infestation in white cabbage in Germany and Japan

An undersowing system with additional intercropping of flowering plants was assessed in field trials in Germany and Japan to estimate regulating effects on pests and possible negative effects on white cabbage (Brassica oleracea var. capitata). In particular, we tested cabbage undersown with wheat (Triticum aestivum L.) and cabbage undersown with wheat plus additional sweet alyssum (Lobularia maritima L. Desv.) intercropping. Counts of the aphid species Brevicoryne brassicae (L.) and Myzus persicae (Sulzer), as well as related predators on cabbage plants, were determined. Abundance of Phyllotreta spp. flea beetles and their feeding damage on cabbage plants were recorded and cabbage yield was compared. In both countries, trials showed that wheat undersowing reduced the abundance of M. persicae but not B. brassicae. The occurrence of natural enemies on cabbage plants was not significantly affected by any of the companion plants. Additional sweet alyssum intercropping increased the abundance of adult hoverflies at the German but not at the Japanese location. However, it also significantly increased flea beetle infestation on cabbage plants at both locations. Neither wheat undersowing nor additional sweet alyssum intercropping significantly reduced cabbage harvest weight.In conclusion, adding companion plants can be a promising method to improve pest control in vegetable crops. However, intercropping crucifer crops with sweet alyssum may not be recommended in regions where flea beetles are a relevant pest because of the observed enhancing effect on them. In contrast, to prove the positive effect of wheat undersowing on white cabbage, results from further years of investigation are needed.

Effects of seed treatments and storage duration on Myzus persicae (Hemiptera: Aphididae) and amaranth fresh leaf yield.

The green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), is a key insect pest of amaranth in East Africa. Pest management has been restricted to indiscriminate application of insecticides to foliage. Applying systemic insecticides to seeds has been shown to manage aphid infestations in other crop systems. We evaluated two commercially available seed treatments in East Africa, Apron Star (thiamethoxam 20 g/kg + metalaxyl-M 20 g/kg + difenoconazole 2 g/kg) and Menceron (imidacloprid 233 g/L + pencycuron 50 g/L + thiram 107 g/L) for their efficacy against M. persicae and impact on fresh leaf yield with two Amaranthus species, Amaranthus blitum (2 selections), Amaranthus hybridus (4 selections) and untreated control. Two storage periods (24 h and 3 months) with seed treatments were used. Each amaranth selection was treated individually with Apron and Monceren or untreated, and seeds were planted either 24 h or 3 months after treatment. Significant reduction in live aphids was observed with A. blitum and A. hybridus selections grown with seed treatment, at 6, 8 and 10 d after infestation (DAI) when compared with seeds grown without seed treatment. Untreated seeds of A. hybridus (selection 5) had significantly higher number of live aphids up to 243, greater percentage of damaged leaves and leaf damage score up to 84% and 64% respectively when compared with treated seeds of specific amaranth at 10 DAI. No significant difference was noted between seed treatment and storage time. Amaranth seeds treated with Monceren offered more protection against infestations of Myzus persicae than amaranth seeds treated with Apron under high tunnel experiments.

Screening of Brassica genotypes against mustard aphid under northern Indian Shivalik hill conditions

Oilseed Brassica plays the important role in Indian agriculture in relation to oil production. The major insects in Brassicas are Lipaphis erysimi, Bagrada hilaris, Athalia lugens proxima (Klug), Chromatomyia horticola Goureau, Pieris rapae, Bagrada cruciferarum Kirkaldy are of practical importance. Out of these, the Lipaphis erysimi (Kalt.) [mustard aphid], a part of family Aphididae with order Hemiptera leads to great yield losses in rapeseed-mustard. To overcome this problem, the easiest solution is to grow resistant and tolerant varieties. The screening is done on the basis of aphid infestation index scale for categorization of the genotypes into resistance and tolerance. Experiments were carried out at the experimental farm of Division of Plant Breeding and Genetics, Faculty of Agriculture, Sher-e-Kashmir University of Agricultural Sciences and Technology, Jammu during rabi of 2017–18 and 2018–19 to evaluate mustard germplasm against Lipaphis erysimi and selecting the resistant genotypes of Brassica for its cultivation and expansion purposes. A total of fifteen cultivars were evaluated based on population buildup of mustard aphid and infestation index. The genotypes RSPN-28, CNH-11-13, RL-1359, HNS-1101, GSC-101, CNH-11-2 and HNS-1102 were found moderately resistant during the rabi 2017–2018 and during rabi 2018–2019, due to weather conditions only two genotypes CNH-13-2 and RSPN-29 were found moderately resistant and susceptible against aphid infestation.

Effects of Weather on Sugarcane Aphid Infestation and Movement in Oklahoma

Sugarcane aphids have caused economic damage on sorghum and other grain production in Oklahoma. When applied in a timely manner, insecticides provide efficient control; however, it is difficult to protect against the unexpected heavy infestations that have appeared frequently since 2016. This article evaluates the effect of spatial and temporal patterns of weather variables on sugarcane infestation airborne movements. Econometric methods identified persistent northwesterly wind patterns that explain aphid movements. Results serve as a base for sugarcane aphid infestation predictions and to assist stakeholders in developing an early warning system for sorghum producers.