Myzus Persicae Research Articles

Tri‐Trophic Interactions of Cabbage Cultivars, a Generalist Aphid, Myzus persicae (Sulzer) and the Braconid Diaeretiella rapae McIntosh

ABSTRACTThe tri‐trophic interactions among five cabbage (Brassica oleracea var. capitata) cultivars—Copenhagen Market (CM), Red Acre (RA), Vertus Savoy (VS), Sugarloaf (SL) and Danish Ballhead (DBH)—a generalist aphid, Myzus persicae (Sulzer) and its parasitoid, Diaeretiella rapae McIntosh, were assessed. Copenhagen Market, known for its reported aphid resistance, recorded the fewest aphids (9.11 per plant; F = 6.50; df = 4, p < 0.01), followed closely by Red Acre (11.83 per plant), which was statistically similar. Upon aphid attack, all cultivars produced plant volatiles that influenced the attraction of the parasitoid, D. rapae. Copenhagen Market consistently showed a higher response across cultivar combinations, attracting 62.59%–67.50% of parasitoids. It also recorded a higher parasitisation rate (39.9%; F = 5.94; df = 4/20, p < 0.01) in a multiple‐choice test. The results indicate that cabbage cultivars employ both constitutive and induced resistance, as aphid‐resistant cultivars were also found to be more attractive to parasitoids. In addition to plant odour cues, factors such as plant colour, texture and host aphid kairomones can influence the orientation and parasitisation by D. rapae.

The Altered Lipid Composition and Key Lipid Metabolic Enzymes in Thiacloprid-Resistant Myzus persicae, with Special Attention Paid to the Function of MpTHEM6a

Neonicotinoid resistance is increasingly prevalent in the agricultural pest Myzus persicae. Lipids play a critical role in insect defense systems, but their contribution to insect neonicotinoid resistance is disregarded. We conducted metabolomics and transcriptomics studies on M. persicae thiacloprid-resistant (THG-R) and -susceptible (FFJ-S) populations. A total of 149 lipid metabolites were identified, with 90 upregulated and 59 downregulated in THG-R compared to in FFJ-S. Metabolites in the arachidonic acid (AA) pathway substantially varied between THG-R and FFJ-S. For example, arachidonic acid, (±)11-HETE, and prostaglandin B1 were significantly upregulated, while prostaglandin A1, tetranor-PGDM, 8,15-diHETE, and (±)11(12)-EET were significantly decreased in THG-R. Transcriptomics profiles and qPCR indicated that lipid metabolic enzymes, including fatty acid synthase (FAS), the elongase of very-long-chain fatty acids (ELO), fatty acid desaturase (FAD), and phospholipase (PL) genes, were not overexpressed in THG-R. Among the twelve thioesterase genes, only MpTHEM6a was significantly upregulated in THG-R. Knocking down the expression of MpTHEM6a in THG-R significantly increased the toxicity of the three neonicotinoids, reduced the lifespan of adults, and decreased the number of nonviable nymphs produced by female adults. The metabolites AA, (±)11-HETE, and prostaglandin B1 are potential biomarkers in neonicotinoid-resistant M. persicae. MpTHEM6a may become a potential target for combating neonicotinoid-resistant M. persicae.

Life table and feeding behavior of Myzus persicae (Hemiptera: Aphididae) at sublethal concentrations of Afidopyropen, Spirotetramat and sulfoxaflor

AbstractThe green peach aphid Myzus persicae Sülzer is a major insect pest of cruciferous plants, including vegetables such as Chinese cabbage. The objective of the present study was to determine the effects of sublethal afidopyropen and spirotetramat concentrations on the survival and reproduction of M. persicae. In addition, we used an electrical penetration graph (EPG) to study the feeding behavior of M. persicae on Chinese cabbage leaves treated with various concentrations of afidopyropen, spirotetramat and sulfoxaflor. The results showed that sublethal concentrations (LC10 and LC30) of afidopyropen and spirotetramat significantly decreased adult longevity and fecundity. However, sulfoxaflor had no significant effects. Several population parameters, including the net reproductive rate (R0), intrinsic rate of increase (rm), mean generation time (T), finite rate of increase (λ), and doubling time (DT), were significantly decreased only at the LC30 of spirotetramat. According to the EPG feeding behavior analyses, when all three insecticides were applied at LC30, the nonpenetration (NP) waveform significantly increased. The above results can be used as basic data for the well‐planned use of insecticides.

Discovery of Acaricidal, Insecticidal, and Fungicidal Candidates Inspired by Natural Ethyl Cinnamate Compounds Isolated from Polygonum orientale L.

As a continuation of our research on the pesticide development of Polygonum orientale L., the chemical constituents of the seeds of P. orientale were systematically investigated. Eleven natural compounds (PO-1 to PO-11) were isolated from the EtOAc extract of P. orientale. Notably, compound PO-9 and its dimeric compound PO-10 were first isolated from P. orientale and possessed excellent acaricidal activity against Tetranychus cinnabarinus. With PO-9 and PO-10 as the lead compounds, two series of cinnamate derivatives were further synthesized, and their acaricidal, insecticidal, and fungicidal activities were evaluated systematically. The insecticidal activity results showed that dimeric derivative NKY-70 displayed the highest acaricidal activity against T. cinnabarinus and insecticidal activities against Brevicoryne brassicae and Myzus persicae. Furthermore, most of these compounds showed excellent in vitro antifungal activity against plant fungi. Compound NKY-66 displayed the highest and broad spectrum of antifungal activity against 23 fungi, and the respective EC50 values were 0.09, 0.08, 0.12, 0.18, 0.12, and 0.09 mg/mL against Valsa mali, Fusarium oxysporum f. sp. cucumerinum, Fusarium graminearum, Magnaporthe oryzae, Colletotrichum capsici, and Phytophthora infestans, which were more potent than those of chlorothalonil and procymidone. Moreover, the in vivo fungicidal evaluation also demonstrated that compound NKY-66 could effectively control plant fungal diseases in the greenhouse and in the field, such as damping off, powdery mildew, and cucumber downy mildew. Therefore, these findings implied that the cinnamate derivative NKY-66 displayed superior in vitro and in vivo fungicidal activities and could be a potential candidate against plant fungal diseases.

Bell pepper endornavirus alters green peach aphid (Hemiptera: Aphididae) host choice and population dynamics.

Bell pepper endornavirus (BPEV) Alphaendornavirus capsici (Endornaviridae) is an RNA virus that infects many pepper (Capsicum annuum) horticultural types and is seed transmitted. BPEV does not cause apparent symptoms and is found at every plant developmental stage. During the domestication of bell pepper, plant breeders, unaware of the existence of endornaviruses in the germplasm, selected endornavirus-infected genotypes. This could be an indication that the presence of endornaviruses in this crop is beneficial. Among the possible beneficial effects that endornaviruses may provide to their host could include tolerance or resistance to biotic and abiotic agents and, therefore, may have evolved a symbiotic relationship with their hosts. With this in mind, we set out to determine host preference, host suitability, and population dynamics of green peach aphid Myzus persicae (Sulzer) on BPEV-infected and virus-free bell pepper near-isogenic lines. During choice bioassay experiments, we observed that a higher proportion of M. persicae adults settled on BPEV noninfected leaves as compared to BPEV-infected leaves. Life table analysis revealed that M. persicae performed less well on BPEV-infected leaf tissues, with reductions in longevity, progeny, and intrinsic rate of increase. These results indicate BPEV is beneficial to its host, protecting against an important generalist pest.

Transcriptional and physiological plasticity of the green peach aphid (Hemiptera: Aphididae) to cabbage and pepper plants.

Defensive metabolites and nutrient restriction of host plants are 2 major obstacles to the colonization of insect herbivores. The green peach aphid (GPA) Myzus persicae (Sulzer) broadly colonizes plants with diverse nutritional and defensive traits. However, how GPA adapts to nutritional and defensive traits within different plants remains largely unknown. To elucidate this, we first investigated the performances and transcriptomes of GPA feeding on cabbage Brassica oleracea and pepper Capsicum annuum. The green peach aphid had lower weight and fecundity when feeding on cabbage than on pepper. The transcriptomic analysis found 824 differentially expressed genes (DEGs), and 13 of the top 20 Kyoto Encyclopedia of Genes and Genomes pathways are related to nutrient metabolism, energy metabolism, and detoxification. Specifically, we found 160 DEGs associated with the metabolism of protein and amino acids, sugar and lipids, and xenobiotic substances, 86 upregulated in cabbage-fed GPA. Fourteen cathepsin B genes were strongly upregulated in cabbage-fed GPA, and were enriched in lysosome pathway and 2 dominated gene ontology terms peptidase activity and proteolysis. In addition, cabbage-fed GPA upregulated sugar and lipid digestion, while downregulated lipid biosynthesis processes. Furthermore, 55 metabolic detoxification enzyme genes were differentially expressed between GPA on 2hosts, and detoxification enzyme activities of GPA indeed changed accordingly to the host. Then, we found that cabbage has lower amino acids nutrition quality for GPA compared to pepper. Our results suggested that adjustment of nitrogen nutrient metabolism, sugar and lipid metabolism, and metabolic detoxification in a host-specific manner play crucial roles in the adaptations of GPA to different host plants.

Bio-Pesticidal Potential of Nanostructured Lipid Carriers Loaded with Thyme and Rosemary Essential Oils against Common Ornamental Flower Pests

The encapsulation of essential oils (EOs) in nanostructured lipid carriers (NLCs) represents a modern and sustainable approach within the agrochemical industry. This research evaluated the colloidal properties and insecticidal activity of NLCs loaded with thyme essential oil (TEO-NLC) and rosemary essential oil (REO-NLC) against three common arthropod pests of ornamental flowers: Frankliniella occidentalis, Myzus persicae, and Tetranychus urticae. Gas chromatography–mass spectrometry (GC-MS) analysis identified the major chemical constituents of the EOs, with TEO exhibiting a thymol chemotype and REO exhibiting an α-pinene chemotype. NLCs were prepared using various homogenization techniques, with high shear homogenization (HSH) providing the optimal particle size, size distribution, and surface electrical charge. A factorial design was employed to evaluate the effects of EO concentration, surfactant concentration, and liquid lipid/solid lipid ratio on the physicochemical properties of the nanosuspensions. The final TEO-NLC formulation had a particle size of 347.8 nm, a polydispersity index of 0.182, a zeta potential of −33.8 mV, an encapsulation efficiency of 71.9%, and a loading capacity of 1.18%. The REO-NLC formulation had a particle size of 288.1 nm, a polydispersity index of 0.188, a zeta potential of −34 mV, an encapsulation efficiency of 80.6%, and a loading capacity of 1.40%. Evaluation of contact toxicity on leaf disks showed that TEO-NLC exhibited moderate insecticidal activity against the western flower thrips and mild acaricidal activity against the two-spotted spider mite, while REO-NLC demonstrated limited effects. These findings indicate that TEO-NLCs show potential as biopesticides for controlling specific pests of ornamental flowers, and further optimization of the administration dosage could significantly enhance their effectiveness.

Genome‑wide identification of circular RNAs and MAPKs reveals the regulatory networks in response to green peach aphid infestation in peach (Prunus persica)

The green peach aphid (GPA), Myzus persicae (Sulzer), is a serious agricultural pest with a worldwide distribution and a vector of over 100 plant viruses. Various pathways, such as the mitogen-activated protein kinase (MAPK) cascades, play pivotal roles in signaling plant defense against pest attack, and circular RNAs (circRNAs) regulate the expression of mRNAs in response to pest attack. However, the mechanism underlying peach (Prunus persica) response to GPA attack remains unclear. The present study initially identified and characterized 316 circRNAs and 18 PpMAPKs from healthy and GPA-infested peach leaves by whole-transcriptome sequencing and predicted the differentially expressed circRNAs (DECs) after GPA infestation. PCR and Sanger sequencing confirmed the presence of six DECs in peach samples. Besides, RNA sequencing analysis detected 13 DECs, including 5 upregulated and 8 downregulated ones, in peach in response to the GPA attack. Gene ontology (GO) enrichment analysis indicated that specific DECs play crucial roles in the MAPK signaling pathway, and qRT-PCR revealed that GPA infestation altered the expression patterns of PpMAPKs. Finally, five circRNAs, three microRNA (miRNAs), and two MAPK target genes were identified to interact as a network and perform critical roles in modulating the MAPK pathway in the peach during GPA infestation.

Interplay between a polerovirus and a closterovirus decreases aphid transmission of the polerovirus.

Multi-infection of plants by viruses is very common and can change drastically infection parameters such as virus accumulation, distribution, and vector transmission. Sugar beet is an important crop that is frequently co-infected by the polerovirus beet chlorosis virus (BChV) and the closterovirus beet yellows virus (BYV), both vectored by the green peach aphid (Myzus persicae). These phloem-limited viruses are acquired while aphids ingest phloem sap from infected plants. Here we found that co-infection decreased transmission of BChV by ~50% but had no impact on BYV transmission. The drastic reduction of BChV transmission was due to neither lower accumulation of BChV in co-infected plants nor reduced phloem sap ingestion by aphids from these plants. Using the signal amplification by exchange reaction fluorescent in situ hybridization technique on plants, we observed that 40% of the infected phloem cells were co-infected and that co-infection caused redistribution of BYV in these cells. The BYV accumulation pattern changed from distinct intracellular spherical inclusions in mono-infected cells to a diffuse form in co-infected cells. There, BYV co-localized with BChV throughout the cytoplasm, indicative of virus-virus interactions. We propose that BYV-BChV interactions could restrict BChV access to the sieve tubes and reduce its accessibility for aphids and present a model of how co-infection could alter BChV intracellular movement and/or phloem loading and reduce BChV transmission.IMPORTANCEMixed viral infections in plants are understudied yet can have significant influences on disease dynamics and virus transmission. We investigated how co-infection with two unrelated viruses, BChV and BYV, affects aphid transmission of the viruses in sugar beet plants. We show that co-infection reduced BChV transmission by about 50% without affecting BYV transmission, despite similar virus accumulation rates in co-infected and mono-infected plants. Follow-up experiments examined the localization and intracellular distribution of the viruses, leading to the discovery that co-infection caused a redistribution of BYV in the phloem vessels and altered its repartition pattern within plant cells, suggesting virus-virus interactions. In conclusion, the interplay between BChV and BYV affects the transmission of BChV but not BYV, possibly through direct or indirect virus-virus interactions at the cellular level. Understanding these interactions could be crucial for managing virus propagation in crops and preventing yield losses.

JAK/STAT signaling pathway is involved in antibacterial immunity in the green peach aphid Myzus persicae (Sulzer)

The Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway within the innate immune system plays a crucial role in defending insects against bacterial, fungal, and viral pathogens. In this study, we identified and cloned five key genes of this signaling pathway in Myzus persicae: MpDome-1, MpDome-2, MpJak, MpStat92E-1, and MpStat92E-2. Our results illustrated that these genes were highly expressed in first, second and third-instar nymphs. Tissue-specific expression analysis revealed that the five genes were predominantly expressed in the gut. Upon bacterial challenge, particularly with Staphylococcus aureus, the expression levels of all five genes were significantly upregulated. Additionally, Escherichia coli infection significantly upregulated the expression levels of MpDome-1 and MpDome-2, while MpJak, MpStat92E-1 and MpStat92E-2 were weakly upregulated. Functional analysis through RNA interference-mediated knockdown of these target genes revealed a significant increase in mortality following infection with E. coli and S. aureus compared with the control group. These findings suggest that the JAK/STAT signaling pathway is crucial for immune defense against bacterial infections in M. persicae.

Genetic diversity of soybean dwarf virus in two regions of mainland Australia

Soybean dwarf virus (SbDV; family Tombusviridae, genus Luteovirus, species Luteovirus glycinis) is an RNA plant virus that is transmitted solely by aphids in a persistent, circulative and non-propagative manner. SbDV causes significant losses in cultivated Fabaceae, especially in subterranean clover (Trifolium subterraneum) pastures of mainland Australia. SbDV isolates are classified into four phenotypically distinguishable strains: YP, YS, DP, and DS. Y and D strains differ primarily in their host range, and P and S strains in their primary vector species. Genetically, Y and D strains separate into two clades in every genomic region except for the N-terminal region of the readthrough domain (N-RTD), in which P and S strains separate. SbDV diversity in Australia has yet to be investigated, so in this study, 41 isolates were collected from six different host species across two production regions of Australia: the south coast of Western Australia (‘south-west’) and northern New South Wales/southern Queensland (‘north-east’). A near-complete genome sequence of each isolate was obtained, and together with all 50 whole-genome sequences available in the GenBank database, underwent phylogenetic analysis of the whole genome nt and the N-RTD aa sequences. At the whole-genome level, the isolates separated into D and Y clades. At the N-RTD level, most of the isolates separated into P and S clades. All south-west isolates and 11 of the 31 north-east isolates were in the Y clade, and the remaining 20 north-east isolates were in the D clade. Except for one isolate that fell outside the P and S clades, all south-west and north-east isolates were in the P clade, suggesting that they are transmitted by Acyrthosiphon pisum and Myzus persicae. Available biological data largely supported the phenotypic inferences made from the phylogenetic analysis, suggesting that genetic data can provide critical epidemiological insights, provided that sufficient biological data have been collected.

Garlic as a companion plant for suppressing Myzus persicae infestation in Brassica rapa

Companion planting, the practice of growing different plant species together, can be a sustainable pest management strategy. However, the specific role of garlic as a companion plant for Brassica in aphid suppression, particularly against Myzus persicae (Sulzer) (Hemiptera: Aphididae), is not well understood. This study investigated the potential of planting garlic (Allium sativum L., Asparagales: Amaryllidaceae) with Brassica rapa L. (Brassicales: Brassicaceae) to reduce M. persicae infestations and explores its impact on the biocontrol agent Harmonia axyridis Pallas (Coleoptera: Coccinellidae). We hypothesized that the combination of A. sativum and B. rapa would synergistically reduce aphid infestations compared to Brassica monocultures. To test this, M. persicae performance was evaluated on Brassica plants under three conditions: a single Brassica plant (B), two Brassica plants (BB), and a Brassica plant with garlic (BG). Parameters such as aphid survival, fecundity, developmental time, and population increase were measured. Additionally, Y-olfactometer bioassays assessed the behavioral responses of M. persicae and H. axyridis. The results showed that the BG combination significantly reduced aphid survival, fecundity, and population growth while delaying developmental time compared to B and BB. M. persicae preferred volatiles from B and BB plants, while H. axyridis was more attracted to BG volatiles, indicating garlic's potential to enhance biocontrol agent recruitment. This study highlights the potential of garlic as a companion plant to improve Brassica crop protection against M. persicae and enhance the effectiveness of biocontrol agents.

Hyperspectral imaging for pest symptom detection in bell pepper

BackgroundThe automation of pest monitoring is highly important for enhancing integrated pest management in practice. In this context, advanced technologies are becoming increasingly explored. Hyperspectral imaging (HSI) is a technique that has been used frequently in recent years in the context of natural science, and the successful detection of several fungal diseases and some pests has been reported. Various automated measures and image analysis methods offer great potential for enhancing monitoring in practice.ResultsIn this study, the use of hyperspectral imaging over a wide spectrum from 400 to 2500 nm is investigated for noninvasive identification and the distinction of healthy plants and plants infested with Myzus persicae (Sulzer) and Frankliniella occidentalis (Pergande) on bell peppers. Pest infestations were carried out in netted areas, and images of single plants and dissected leaves were used to train the decision algorithm. Additionally, a specially modified spraying robot was converted into an autonomous platform used to carry the hyperspectral imaging system to take images under greenhouse conditions. The algorithm was developed via the XGBoost framework with gradient-boosted trees. Signals from specific wavelengths were found to be associated with the damage patterns of different insects. Under confined conditions, M. persicae and F. occidentalis infestations were distinguished from each other and from the uninfested control for single leaves. Differentiation was still possible when small whole plants were used. However, application under greenhouse conditions did not result in a good fit compared to the results of manual monitoring.ConclusionHyperspectral images can be used to distinguish sucking pests on bell peppers on the basis of single leaves and intact potted bell pepper plants under controlled conditions. Wavelength reduction methods offer options for multispectral camera usage in high-grown vegetable greenhouses. The application of automated platforms similar to the one tested in this study could be possible, but for successful pest detection under greenhouse conditions, algorithms should be further developed fully considering real-world conditions.

Transcriptional reprogramming in the entomopathogenic fungus Metarhizium brunneum and its aphid host Myzus persicae during the switch between saprophytic and parasitic lifestyles

BackgroundThe fungus Metarhizium brunneum has evolved a remarkable ability to switch between different lifestyles. It develops as a saprophyte, an endophyte establishing mutualistic relationships with plants, or a parasite, enabling its use for the control of insect pests such as the aphid Myzus persicae. We tested our hypothesis that switches between lifestyles must be accompanied by fundamental transcriptional reprogramming, reflecting adaptations to different environmental settings.ResultsWe combined high throughput RNA sequencing of M. brunneum in vitro and at different stages of pathogenesis to validate the modulation of genes in the fungus and its host during the course of infection. In agreement with our hypothesis, we observed transcriptional reprogramming in M. brunneum following conidial attachment, germination on the cuticle, and early-stage growth within the host. This involved the upregulation of genes encoding degrading enzymes and gene clusters involved in synthesis of secondary metabolites that act as virulence factors. The transcriptional response of the aphid host included the upregulation of genes potentially involved in antifungal activity, but antifungal peptides were not induced. We also observed the induction of a host flightin gene, which may be involved in wing formation and flight muscle development.ConclusionsThe switch from saprophytic to parasitic development in M. brunneum is accompanied by fundamental transcriptional reprogramming during the course of the infection. The aphid host responds to fungal infection with its own transcriptional reprogramming, reflecting its inability to express antifungal peptides but featuring the induction of genes involved in winged morphs that may enable offspring to avoid the contaminated environment.

Efficacy of Certain Bio-Pesticides against the Major Insect Pests of Broccoli (Brassica oleracea var. italica L.)

The field experiment was undertaken at the Experimental Farm, Department of Entomology, School of Agricultural Sciences (SAS), Medziphema Campus, Nagaland University, during the period of November 2021 to February 2022 to study the efficacy of certain bio-pesticides against major insect pests of broccoli. The experiment was conducted using Randomized Block Design (RBD) with six treatments including control and replicated four times. The study revealed that Indian cabbage white, Pieris spp. and green peach aphid, Myzus persicae have been found to be the major insect pest in broccoli. It is recorded that the highest (73.49%) population reduction of M. persicae was obtained from the plot treated with emamectin benzoate 5% SG and the highest (90.16%) population reduction of Pieris spp. was recorded on the plot treated with spinosad 45% SG. Therefore, the study concluded that use of bio-pesticides offers a great efficacy in controlling the pest and diminish the pesticides related issue.

Influence of genetic and environmental factors on the success of endosymbiont transfers in pest aphids.

There is increasing interest in exploring how endosymbionts could be useful in pest control, including in aphids, which can carry a diversity of endosymbionts. Endosymbionts often have a large impact on host traits, and their presence can be self-sustaining. Identifying useful host-endosymbiont combinations for pest control is facilitated by the transfer of specific endosymbionts into target species, particularly if the species lacks the endosymbiont. Here, we complete a comprehensive literature review, which included 56 relevant papers on endosymbiont transfer experiments in aphids, to uncover factors that might influence transfer success. We then report on our own microinjection attempts of diverse facultative endosymbionts from a range of donor species into three agriculturally important aphid species as recipients: the green peach aphid (Myzus persicae), bird cherry-oat aphid (Rhopalosiphum padi), and Russian wheat aphid (Diuraphis noxia). Combining this information, we consider reasons that impact the successful establishment of lines carrying transferred endosymbionts. These include a lack of stability in donors, deleterious effects on host fitness, the absence of plant-based (versus vertical) transmission, high genetic variation in the endosymbiont, and susceptibility of an infection to environmental factors. Taking these factors into account should help in increasing success rates in future introductions.

One-step TaqMan® RT-qPCR detection of sugar beet-infecting poleroviruses in Myzus persicae from yellow water pan traps opens up new possibilities for early risk assessment of virus yellows disease

Virus yellows disease (VY) is a major threat to sugar beet production in Europe. Beet chlorosis virus (BChV) and beet mild yellowing virus (BMYV) are of particular economic importance and are both persistently transmitted by the aphid vector Myzus persicae. As part of integrated pest management strategies, M. persicae influx into sugar beet fields is recorded weekly using yellow water pan traps. To date, only ELISA and RT-PCR assays have been described for BChV and BMYV detection in individual aphids.In this study, we describe for the first time two one-step TaqMan® RT-qPCR assays designed for the specific detection of BChV and BMYV in M. persicae after 7d incubation in water pan trap medium. Both viruses were reproducibly detected in individual aphids. After 7d incubation in trap medium, both viruses were reproducibly detected in individual aphids, as well as in one viruliferous aphid in a pool of 99 non-viruliferous aphids. Significant correlations can be shown between different mixing ratios of viruliferous to non-viruliferous aphids and Ct values of total RNA templates, allowing the percentage of viruliferous aphids in yellow water pan traps to be estimated using a standard curve.The described methodology provides a high sensitivity combined with a high sample throughput and can be used, after evaluation in the field, for practical monitoring, risk modelling and development of decision support systems for VY.

Isolation and identification of the main components of garlic, Allium sativum, volatiles and their determination of repellent or toxic activities on green peach aphid, Myzus persicae

AbstractTo determine the control mechanism of garlic on Myzus persicae, volatiles from garlic plants were collected, and the components were determined by GC–MS. Then, the volatile extracts and standard components were screened by electroantennogram (EAG) apparatus and Y‐tube olfactometer, and the toxic effects were determined by the immersion method. The results showed the main components from garlic plant volatile were 2‐methoxyphenol, 2,4‐di‐tert‐butylphenol, diallyl disulfide, butyl phthalate esters, (1‐hydroxycyclohexyl) phenyl ketone, and 2,6‐di‐tert‐butylp‐cresol. The volatile extracts and the standard components had significant repellent effects (P ≤ 0.05) on M. persicae when the volume ratio was 1:100. The relative values of EAG from volatile extracts and diallyl disulfide were significantly higher than those of the other substances (P ≤ 0.05) when the volume ratio was 1:100. The toxicity of garlic volatile extracts to M. persicae significantly (P ≤ 0.05) increased with increasing concentration. After 72 h (treated), the adjusted mortality of the extract to M. persicae was 36.99% at 90 ml/L. The standard components had the significant toxic effect on M. persicae at 30 mg/mL, and the rates of mortality were over 78.95%. Thus, the results suggested that the volatile extracts and the four standard components from garlic plants had significant repellent effects and electroantennogram responses for M. persicae, and the toxic effects were stronger than the repellent effects for M. persicae.

An effective dosage of neem (Azadirachta indica Juss) and aloe vera (Aloe barbadensis Miller) extracts against adult aphid (Myzus persicae Sulzer) and melon flies (Bactrocera cucurbitae Coquillet)

The objective of the study was to evaluate the efficaciousness dosage of aqueous extracts of neem (Azadirachta indica Juss) and aloe vera (Aloe barbadensis Miller) at different concentrations (40%, 60%, and 80%) against adult melon flies (Bactrocera cucurbitae Coquillet) and aphids (Myzus persicae Sulzer) in laboratory conditions. The experiments were designed and conducted from April to June 2023 at Sokoine University of Agriculture, Tanzania. The study found that as extract concentrations increased, there was a noticeable drop in insect survival. The dosage of 80% at 48 hours and 60% at 72 hours were observed to perform better as few were observed to survive. At the highest dosage of 80% and 60%, extracts from neem and aloe vera both resulted to 100% insect mortality. The results highlight the potential of aloe vera and neem extracts to have a positive effect on insect pest management rather than untreated crops.

Optimization of vine killing date for maximum seed-tuber yield and minimum exposure to late-season aphid vectors in potato

Short-duration and early-bulking potato varieties are well-suited for commercial cultivation in the subtropical Indo-Gangetic plains of India. To maximize seed tuber yield, prevent late-season exposure to aphid vectors, and facilitate the timely planting of wheat crops during the rabi season, it is essential to cut the haulms (vines) of seed potatoes at the earliest possible time. A study was conducted to standardize the optimal vine-killing date for two popular potato varieties in the north-western plains of India, Kufri Pukhraj and Kufri Jyoti, by examining variations in seed yield across different vine-killing dates and assessing the incidence of aphid vectors transmitting potato viruses. Tubers were planted on 15 October for two consecutive seasons, and haulms were cut at 70, 80, and 90 days after planting (DAP), with continuous monitoring of aphid populations. Results showed that total tuber yield and tuber numbers increased with delayed vine-killing. Similarly, the yield and number of oversized tubers significantly rose as the vine-killing date was extended. However, seed-size and undersized tuber yields were largely unaffected, while the number of undersized tubers decreased between 70 and 90 DAP. Further, the gain in total tuber yield and yield of over-sized tubers occurred mainly during 70–80 DAP for Kufri Pukhraj in contrast to Kufri Jyoti where maximum increase occurred between 80 and 90 DAP. Therefore, it is concluded that the optimum time of vine killing for maximum seed tuber yield is directly linked to the tuber growth cycle of individual variety. The period of maximum incidence of aphid vectors varied between the two years. Based on the incidence of Myzus persicae, the seed crops in north-western plains of India should not be extended beyond last week of December although real time monitoring of the aphid incidence is recommended.