Aphid Infestation Research Articles

Nutrition Rather Than Phytohormone-Dependent Defense of Host Plant Mediates the Different Response of Red- and Green-Morph Pea Aphids to Nitrogen Fertilization

Nitrogen fertilization is widely known to affect plant metabolism, which subsequently influences phytophagous insects through a bottom-up effect. The interplay between plants and insects is often overlooked in studies examining the effects of nitrogen fertilization on insect performance. Here, we assessed the performance of green and red morphs of pea aphid Acyrthosiphon pisum feeding on alfalfa Medicago truncatula with and without nitrogen fertilization and examined how nitrogen fertilization and aphid infestation affect plant amino acid composition and phytohormone-dependent defenses. The results showed that nitrogen fertilization significantly enhanced the growth rate and fecundity of the green-morph aphid but only slightly increased the growth rate of the red morph. The feeding behaviors of the two morphs of aphid were similarly inhibited by nitrogen fertilization, manifested as prolonged stylet pathway duration and shortened phloem ingestion duration. With nitrogen fertilization, the green-morph-aphid-infested plant accumulated more free amino acids, particularly essential amino acids, when compared with the red-morph aphid. Furthermore, the infestation of both morphs of aphid repressed the expression of genes involved in salicylic acid-dependent defense while enhancing those involved in jasmonic acid/ethylene signaling under nitrogen fertilization. These results suggest that nitrogen fertilization and aphid infestation interact in manipulating plant metabolism, with nutritional changes playing a vital role in the aphid morph-specific growth and fecundity response to nitrogen fertilization.

The Effects of Lead and Cross-Talk Between Lead and Pea Aphids on Defence Responses of Pea Seedlings

The main goal of this study was to investigate the effect of lead (Pb) at various concentrations, as an abiotic factor, and the cross-talk between Pb and pea aphid (Acyrthosiphon pisum (Harris)) (Hemiptera: Aphididae), as a biotic factor, on the defence responses of pea seedlings (Pisum sativum L. cv. Cysterski). The analysis of growth parameters for pea seedlings demonstrated that Pb at a low concentration, i.e., 0.025–0.0625 mM Pb(NO3)2, caused a hormesis effect, i.e., stimulation of seedling growth, whereas Pb at higher concentrations, i.e., 0.01–0.325 mM Pb(NO3)2, inhibited growth, which manifested as the inhibition of length and fresh biomass. The differences in the level of the main defence-related phytohormones, such as abscisic acid (ABA), jasmonic acid (JA) and salicylic acid (SA), and indole-3-acetic acid (IAA)—an auxin stimulating plant cell growth—depended on the dose of Pb, aphid infestation and direct contact of the stress factor with the organ. A high accumulation of soluble sugars in the organs of pea seedlings both at sublethal doses and hormetic doses at early experimental time points was observed. At 0 h and 24 h of the experiment, the hormetic doses of Pb significantly stimulated invertase activities, especially in the roots. Moreover, an increase was observed in the pisatin concentration in pea seedlings growing in the presence of different concentrations of Pb and in the case of cross-talk between Pb and A. pisum in relation to the control. Additionally, a significant induction of the expressions of isoflavone synthase (IFS) and 6α-hydroxymaackiain 3-O-methyltransferase (HMM) genes, which participate in the regulation of the pisatin biosynthesis pathway, in pea seedlings growing under the influence of sublethal 0.5 mM Pb(NO3)2 and hormetic 0.075 mM Pb(NO3)2 doses of Pb was noted. The obtained results showed that the response of P. sativum seedlings depends on the Pb dose applied, direct contact of the stress factor with the organ and the duration of contact.

The Interplay of Nitric Oxide and Nitrosative Modifications in Maize: Implications for Aphid Herbivory and Drought Stress.

Nitric oxide (NO) and other reactive nitrogen species (RNS) are considered to be signaling molecules in higher plants involved in the regulation of growth and development processes. However, the molecular mechanisms of their formation, removal, and participation in plant responses to adverse environmental stimuli remain largely unclear. Therefore, the aim of this study was to assess the influence of selected single stresses and combined stresses (i.e., Rhopalosiphum padi L. aphid infestation, drought, aphid infestation, and drought) and post-stress recovery on the contents of NO and peroxynitrite anion (ONOO-), as well as the levels of mRNA and protein nitration (i.e., the 8-nitroguanine and protein 3-nitrotyrosine amounts, respectively), in maize seedlings (Zea mays L.). Moreover, the expression patterns of the two tested genes (nos-ip, encoding nitric oxide synthase-interacting protein, and nr1, encoding nitrate reductase 1) involved in NO metabolism in maize plants were quantified. We identified significant intervarietal, time-course, and stress-dependent differences in the levels of the quantified parameters. Under the investigated stress conditions, the aphid-resistant Waza cv. seedlings were characterized by a higher and earlier NO accumulation and mRNA nitration level and an increased expression of the two target genes (nos-ip and nr1), compared to the aphid-susceptible Złota Karłowa cv. seedlings. Conversely, the Złota Karłowa plants responded with a greater elevation in the content of ONOO- and protein 3-nitrotyrosine than the Waza cv. plants The multifaceted role of NO and its derivatives in maize plants challenged by single and combined stresses, as well as during post-stress recovery, is discussed.

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.

Strip‐cropping legacy enhances potato plant defence responses to aphids via soil‐mediated mechanisms

Abstract Intensive agriculture often comes at the expense of soil health. A shift towards practices that foster soil health will support yield and defences against pests and diseases. Growing crops in monoculture is the standard in modern agriculture, though strip‐cropping, in which different crops are planted in strips, is a promising strategy in the transition towards sustainable agriculture. Increasing crop diversity is hypothesized to positively influence arbuscular mycorrhizal fungi (AMF), thereby enhancing soil health, but the mechanisms by which AMF‐plant symbioses contribute to higher yields and reduced pest populations in strip‐cropping systems remain unclear. We used a green‐house experiment with potato plants to explore the soil legacy effects of mono‐cropping versus strip‐cropping systems, AMF inoculation and aphid infestation on AMF root colonization, the induction of plant defences (untargeted LCMS‐based metabolomics), aphid population size and potato yield. We found that potato plants grown in strip‐cropping soil had higher AMF colonization than plants grown in mono‐cropping soil. Potato plants grown in strip‐cropping soil also had higher shoot nitrogen content, increased solamargine levels, and reduced aphid populations. AMF root colonization was only enhanced by the addition of commercial AMF in mono‐cropping soils. Potato plant metabolites were affected by strip‐cropping soil, including jasmonic acid (JA) derivatives. Structural equation models revealed that strip‐cropping soil directly reduced aphid populations and also had a negative direct effect on the JA precursor OPC‐8, and hydroxyJA‐glucosides, indicating complex effects of strip‐cropping soils on JA‐inducible plant defences. Indirect benefits of strip‐cropping soil and AMF inoculation on tuber yield were mediated by their direct positive effects on plant nitrogen content. Our results emphasize the potential of strip‐cropping to enhance AMF root colonization in the field. We show that soil legacy effects of strip‐cropping alter the plant metabolome in ways that suppress of aphid populations. Strip‐cropping legacy effects are the result of crop diversity, crop neighbour and edge effects resulting from crop management practices. While the mechanisms by which soil from strip‐cropping supresses pest populations still need to be identified, our study underscores the potential for strip‐cropping to enhance pest control and yield via soil mediated processes. Read the free Plain Language Summary for this article on the Journal blog.

Natural variation at the cotton HIC locus increases trichome density and enhances resistance to aphids.

Plant trichomes are an excellent model for studying cell differentiation and development, providing crucial defenses against biotic and abiotic stresses. There is a well-established inverse relationship between trichome density and aphid prevalence, indicating that higher trichome density leads to reduced aphid infestations. Here we present the cloning and characterization of a dominant quantitative trait locus, HIC (hirsute cotton), which significantly enhances cotton trichome density. This enhancement leads to markedly improved resistance against cotton aphids. The HIC encodes an HD-ZIP IV transcriptional activator, crucial for trichome initiation. Overexpression of HIC leads to a substantial increase in trichome density, while knockdown of HIC results in a marked decrease in density, confirming its role in trichome regulation. We identified a variant in the HIC promoter (-810 bp A to C) that increases transcription of HIC and trichome density in hirsute cotton compared with Gossypium hirsutum cultivars with fewer or no trichomes. Interestingly, although the -810 variant in the HIC promoter is the same in G. barbadense and hirsute cotton, the presence of a copia-like retrotransposon insertion in the coding region of HIC in G. barbadense causes premature transcription termination. Further analysis revealed that HIC positively regulates trichome density by directly targeting the EXPANSIN A2 gene, which is involved in cell wall development. Taken together, our results underscore the pivotal function of HIC as a primary regulator during the initial phases of trichome formation, and its prospective utility in enhancing aphid resistance in superior cotton cultivars via selective breeding.

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.

Infestation Rates, Seasonal Abundance of Aphids and Relationships with Some Environmental Factors in Different Forest Habitats in Southwestern Türkiye

Aim of study: It was to determine the infestation rate and seasonal abundance of aphids and their relationships with some environmental factors in forests. Area of study: The study was conducted in Pinus nigra, P. brutia, Cedrus libani, Abies cilicica, Juniperus spp., Quercus spp. and Robinia pseudoacacia forests (34 sampling areas) in Isparta. Materials and methods: Systematic sampling was carried out monthly throughout April-October in 2019-2020. As aphid density and infestation rates were determined, 30 cm shoots were taken from 10 trees. The slope, aspect, elevation, forest characteristics, daily minimum, average, and maximum temperature and total precipitation were recorded. Main results: Abundance were highest in P. nigra, Quercus and Robinia pseudoacacia forests in both years. There was a significant correlation between abundance and development stages (p

Effect of Different Concentrations of Tomato Leaf Extract on Aphid Control in Rape Production in Zimbabwe

Rape (Brassica napus) is an important vegetable crop grown by smallholder farmers in Zimbabwe to achieve food and nutritional security. However, productivity and quality of rape are greatly dampened by aphids which reduce its palatability and quality. Chemical pesticides, while effective, pose environmental risks and can lead to pest resistance and resurgence, besides residual effects and bioaccumulation along the food chain. Tomato leaves are rich in phenolic and flavonoid compounds, that have shown promise as a botanical pesticide against aphids in other crops. This research aimed to establish the aphicidal components in tomato leaf extract using TLC and UV-Vis Spectroscopy; establish toxicity of the extract using laboratory bioassay, investigate the potential of different concentrations of tomato leaf extracts as a natural, environmentally friendly and sustainable approach to pest management against aphids in rape production at Kushinga Phikelela Agricultural College in Zimbabwe. A CRD with four treatments (0%, 20%, 40% and 60% of tomato leaf extract) and distilled water (negative control) replicated five times each was used. Aphid infestation (scored on a scale of 0-9), yield, leaf size, and plant height were measured fortnightly. Data was analysed for statistical significance using ANOVA while separation of significant means was done by Fisher’s Protected Least Significant Difference Test (LSD (5%). The results from combined analysis using TLC and UV- Vis Spectroscopy indicated that tomato leaf extract used in this research contained compounds (Solanine, Tomatine, Chaconine) which are known to be toxic to pests. There was a highly significant (p<0.001) difference among treatments on aphid mortality. The highest aphid mortality (95.57%) while the lowest (4%) was observed in 60% and 0% leaf extract respectively. Aphid infestation, leaf size and plant height were highly significant (P<0.001) during weeks 4, 6, 8 and 10 after transplanting. Aphid infestation in week 10 mean score was 8.8, 6.2, 3.8 and 0.8 for 0%, 20%, 40% and 60% tomato leaf extract respectively. Other parameters such as yield and leaf size were highest in the plots that received 60% tomato leaf extract sprays. Highly significant difference (P<0.001) in yield was observed in weeks 8 and 10, while significant difference (P<0.05) in yield was noted in weeks 4 and 6. However, in week two there were no significant differences among the treatments in yield and aphid infestation. Tomato leaf extracts contain secondary metabolites toxic to aphids and this can be used by resource constrained farmers. We recommend the use 60% tomato leaf extracts to control aphids in rape to sustainably achieve high yields.

Conventional Versus Biorational Insecticides for Controlling Mustard Aphid and Their Effects on Beneficial Insects

Mustard is one of the most important oilseed crops in Bangladesh. However, its production is severely constrained by aphid infestation. Farmers usually spray conventional insecticides to control aphids that negatively affect beneficial insects and environment. Thus, alternatives to conventional insecticides are required. We tested three biorational insecticides (Nimbicidine @ 1ml/L, Spinosad: Libsen 45SC @ 0.5 ml/L and Lufenuron: Hayron 5EC @ 0.5ml/L of water) against aphid infestation and assessed their effect on ladybird beetle and honey bee and compared these effects with two conventional insecticides (Diazinon: Sabion 60EC @ 2ml/L and Cypermethrin: Cypraplus 10EC @ 1ml/L of water) and with an untreated control. The study was conducted in a randomized complete block design with each treatment replicated thrice in the field of Department of Entomology, Bangladesh Agricultural University. Number of infested plants per plot, aphid per plant and per pod, number of ladybird beetle and honey bee per plot was counted and yield per plot was calculated. All tested insecticides reduced aphid infestation compared to untreated control indicating all of them were effective against aphid. However, Lufenuron and Nimbicidine was most effective to reduce plant infestation and number of aphids per plant and pod. Spinosad and Sabion were found fairly effective whereas Cypraplus was found to be least effective. Lufenuron and Nimbicidine did not reduce the number of ladybird beetle and honey bee visit per plot, however, Spinosad and conventional insecticides reduced their number. Lufenuron treated plots provided highest yield (1.35 t/ha) followed by Nimbicidine (1.15 t/ha), Spinosad (1.10 t/ha) and Sabion (1.00 t/ha) whereas Cypraplus treated plots provided lowest yield (0.9 t/ha). In terms of reducing aphid population thus plant infestation and increasing yield, all biorational insecticides performed better than conventional insecticides, however, concerning effect on ladybirds and honey bees, only Lufenuron and Nimbicidine can be recommended to farmers. J Bangladesh Agril Univ 22(3): 335-341, 2024

Assessment of faba bean-cereal intercropping: Impact on black aphids, weed management, and faba bean yield in the Meknes region, Morocco

Abstract This study aimed to evaluate the influence of the association between faba bean and cereal crops on the incidence and severity of black aphids, weed control, and faba bean yield in Meknes region, Morocco. Regression and correlation analyses were performed to examine the relationship between different parameters. The results showed that the combination of faba bean with cereals significantly reduced black aphid infestation, weed density, and biomass compared to faba bean alone. The present study also revealed a positive correlation between reduced aphid incidence and improved faba bean yield. Analyses also revealed significant correlations between weed density and aphid incidence/severity as well as notable associations between faba bean crop biomass, weed biomass, and faba bean yield. These findings underscore the importance of crop associations in enhancing the resilience and productivity of faba beans through integrated aphid and weed management. They highlight the complexity of the interactions between aphids, weeds, and faba bean crops, requiring a holistic approach to understand their impact on crop yield.

Can a Mixture of Farnesene Isomers Avert the Infestation of Aphids in Sugar Beet Crops?

The negative impact of pesticides on the environment and the potential of pest species to develop pesticide resistance make it necessary to explore new methods of pest control. Pheromones and other behavior-modifying semiochemicals are already important in integrated pest management (IPM). (E)-ß-farnesene (EBF) is a semiochemical that acts as an alarm pheromone in aphids. Upon perception of EBF, aphids stop feeding, move away, and sometimes even abandon the host plant. The aphids Myzus persicae and Aphis fabae are significant crop pests and vectors of many harmful phytopathogens affecting sugar beet (Beta vulgaris). Field trials were conducted at different locations in Germany to test whether dispensers containing a mixture of farnesene isomers (FIMs) including EBF were able to reduce the infestation of these species on sugar beet. Our results showed a reduction in aphid abundance in the FIM-treated patches in two out of three sites. Therefore, we hypothesize that FIM dispensers could prevent aphid infestation and could be used in combination with other IPM measures. However, more research is required to increase the effect and ensure the reliability of this method.

Efficacy of arginine kinase as a promising RNAi target in Aphis gossypii genome as revealed through aphid bioassay on field-grown transgenic cotton plants

The cotton aphid Aphis gossypii is a major agricultural pest of cotton that causes substantial damage to the crop not only by sucking sap but also through virus transmission. Globally adopted traditional and contemporary approaches to control aphid infestation have certain limitations and are hazardous to human health. RNA interference (RNAi) technology has unfolded its potential as an effective crop protection strategy against various pests. In this study, we adopted plant-mediated RNAi strategy to enhance aphid resistance in cotton by targeting arginine kinase (AK), which is a crucial enzyme responsible for energy homeostasis in insects. We selected a 312bp dsRNA fragment containing eight siRNAs and showing optimum GC content, Hb index, and stable secondary structure based on computational prediction studies. The binary construct expressing dsRNA was used to transform local cotton variety MNH886 and four transgenic lines were obtained in the T1 generation. Out of the four T1 transgenic cotton lines, dsA-7 exhibited the highest aphid mortality (73.3%), whereas, dsA-1, dsA-3 and dsA-6 revealed 60%, 61%, and 66.6% aphid mortality, respectively, in comparison to 13.3% mortality in the mock control cotton line. Moreover, significant knockdown in mRNA expression of AK was observed in aphids fed dsA-7 which was 79%. In comparison, 54%, 47%, and 45% downregulation was recorded in aphids which fed on dsA-6, dsA-3, and dsA-1 transgenic cotton lines, respectively. These results revealed that plant-mediated downregulation of aphid RNA induced significant RNA interference in A. gossypii which resulted in considerable aphid mortality and led to plant protection against aphids.

Insecticide-free reduction of Myzus persicae aphids on sweet pepper (Capsicum annuum L.) through MgSO4-faciliated amino acid and sugar reallocation

Fruits of sweet pepper (Capsicum annuum L.) are among the most consumed fresh fruits, however, their production can be affected by aphids, which feed on the amino acids in the leaves. Mg2+ in leaves plays a crucial role in the reallocation of amino acids from source organs (leaves) to sink organs (fruits). We hypothesize that foliar application of Mg2+ can reduce free amino acid concentration in leaves by promoting their transfer to sink fruits, thereby compromising aphid colonization by reducing their nutritional basis. To test this, a two-factorial experiment was conducted with sweet pepper subjected to aphid infestation with and without leaf MgSO4 application. The concentration of amino acids, sugars, organic acids and mineral nutrients was analysed in the leaves, leaf phloem sap and fruits. Mg2+application decreased the concentrations of amino acids and sugars that are key for aphid nutrition in both the leaf and phloem sap and increased the size and number fruits, indicating an increased sink strength in response to Mg2+. This response was accompanied by a reduced number of aphids on the entire plant. In results, the sugar and amino acid concentration in the phloem got less attractive for the aphids. We conclude that Mg2+ worsens the nutritional situation for aphids by facilitating the reallocation of metabolites to form fruits.

Niche construction and niche choice by aphids infesting wheat ears

The niche of aphids is largely defined by their consumption of plant phloem sap and its composition, including nutrients and specialized metabolites. Niche construction is the change of the environment by organisms, which may influence the fitness of these organisms and their offspring. To better understand interactions between plants and aphids, it is necessary to investigate whether aphids modify the chemical composition of the phloem sap of their host plants and whether conspecifics are affected by previous infestation. In the current study, ears of wheat (Triticum aestivum) plants were infested with clonal lineages of the English grain aphid (Sitobion avenae) or were left uninfested. The metabolic composition of ear phloem sap exudates was analyzed through amino acid profiling and metabolic fingerprinting. Aphids of the clonal lineages were either put on previously aphid-infested or on uninfested ears and their colony sizes followed over time. Furthermore, it was investigated whether aphids choose one treatment group over another. Sitobion avenae infestation affected the relative concentrations of some metabolites in the phloem exudates of the ears. Compared to uninfested plants, the relative concentration of asparagine was higher after aphid infestation. Colonies grew significantly larger on previously aphid-infested ears, which the aphids also clearly chose in the choice experiment. The pronounced positive effect of previous infestation on aphid colonies indicates niche construction, while the choice of these constructed niches reveals niche choice by S. avenae on wheat. The interplay between these different niche realization processes highlights the complexity of interactions between aphids and their hosts.

Lightweight and accurate aphid detection model based on an improved deep-learning network

Rapid and accurate detection of bamboo aphids can help prevent large-scale aphid infestations from occurring, which is of great significance for increasing bamboo shoot production and economic benefits. Herein, a lightweight and accurate model, SCA-YOLOv5s, was established by integrating ShuffleNetv2 and Coordinate Attention with the YOLOv5s model to detect Takecallis taiwanus on the yellow sticky traps. Specifically, we first replaced the backbone network of YOLOv5s with ShuffleNetv2 to reduce the number of parameters and computational complexity of the model. Second, an anchor optimization method was proposed by combining linear scaling and k-means algorithm to generate appropriate anchor boxes for detecting small-sized alate aphids. Third, the coordinate attention mechanism was added to the neck network to improve the feature extraction ability. To verify the performance of the proposed SCA-YOLOv5s model, eight detection models were constructed with existing deep learning methods, including SSD300, YOLOv3, Faster R-CNN, YOLOv4, YOLOv4-Tiny, YOLOX-Tiny, YOLOv7-Tiny, and YOLOv5s. Results reveal that the SCA-YOLOv5s model achieved higher detection accuracy than the other eight models. Its mean average precision reached 92.2 %. The proposed model has a size of only 6.7 MB, its floating-point operations (FLOPs) is 7.4 × 109, its inference time is 6.6 ms, and compared with YOLOv5s, it is 53.47 % smaller in model size, 55.15 % lower in FLOPs, and 0.8 ms faster in inference time. The results indicate that the proposed model can maintain high detection accuracy while minimizing computation and inference time, which is crucial for deployment in remote areas with low information technology. This study provides valuable technical support for the control of aphids in bamboo forests.

Combined transcriptome and metabolome analysis identifies triterpenoid-induced defense responses in Myzus persicae Sülzer-infested peach.

The defense response of peach (Prunus persica) to insect attack involves changes in gene expression and metabolites. Piercing/sucking insects such as green peach aphid cause direct damage by obtaining phloem nutrients and indirect damage by spreading plant viruses. To investigate the response of peach trees to aphids, the leaf transcriptome and metabolome of two genotypes with different sensitivities to green peach aphid (GPA, Myzus persicae) were studied. The transcriptome analysis of infected peach leaves showed two different response patterns. The gene expression of aphid-susceptible peach plants infected by aphids was more similar to that of the control plants, while the gene expression of aphid-resistant peach plants infected by aphids showed strongly induced changes in gene expression compared with the response in the control plants. Furthermore, gene transcripts in defense-related pathways, including plant-pathogen interaction, MAPK signaling, and several metabolic pathways, were more strongly enriched upon aphid infestation. Untargeted secondary metabolite profiling confirmed that aphid treatment induced larger changes in aphid-resistant peaches than in aphid-susceptible peaches. Consistent with transcriptomic alterations, nine triterpenoids showed extremely significant GPA-induced accumulation in aphid-resistant peaches, whereas triterpenoid abundance remained predominantly unchanged or undetected in aphid- susceptible peaches. Furthermore, some types of transcription factors (including WRKYs, ERFs, NACs, etc.) were more strongly induced upon GPA infestation in aphid-resistant peaches but not in aphid-susceptible peaches. Aphid feeding-dependent transcriptome and metabolite profiles provide the foundation for understanding the molecular mechanisms underlying the response of peach to aphid infestation. These results suggested that accumulation of specialized triterpenoids and the corresponding pathway transcripts may play a key role in peach GPA resistance.

Physiological and metabolomic analyses reveal the resistance response mechanism to tea aphid infestation in new shoots of tea plants (Camellia sinensis)

The tea plant (Camellia sinensis (L.) O. Kuntze) is an important woody economic crop and often attacked by various insect pests such as tea aphids (Toxoptera aurantii Boyer de Fonscolombe). To reveal tea plant responses to tea aphid infestation, tea aphid-resistant cultivar ‘Taicha13’ and -susceptible one ‘Jingfeng’ were first screened, and then widely targeted metabolomics profiling, biochemical parameter and RT-qPCR analyses were performed in three samples, TCN (tea aphid non-infested ‘Taicha13’), JFN (tea aphid non-infested ‘Jingfeng’) and JFA (tea aphid-infested ‘Jingfeng’). The results showed amnio acid (plus proline) and protein content, and amnio acid: sucrose ratio were significantly less abundant in TCN relative to JFN, suggesting TCN is low nutritional quality for tea aphids. Metabolite profiling revealed that flavonoids and JA-isoleucine (JA-Ile) were more enriched in TCN and JFA compared to JFN, proposing effective roles of flavonoids and JA-Ile in tea plant defense against tea aphid infestation. RT-qPCR results demonstrated that five JA biosynthesis genes (CsLOX2, CsLOX3, CsOPR, CsAOC and CsJAR) in exception of CsAOS, and six flavonoid biosynthesis genes (CsPAL, CsC4H, CsCHS1, CsCHS2, CsFL and CsDFR) shared similarly higher abundance in TCN than in JFN, and exhibited elevated expression levels in JFA relative to JFN, further suggesting flavonoids and JA confer tea plant resistance against tea aphid feeding. Overall, our findings uncovered that tea aphid-infestation activated defensive responses and highlighted involvement of nutritional quality, flavonoids and JA-Ile in tea plant resistance against tea aphid infestation.

Selecting appropriate forage cover crops to improve growth, yield, and fruit quality of wolfberry by regulation of photosynthesis and biotic stress resistance

Forage cover crops have the potential to improve soil quality and orchard productivity, but their effects on wolfberry (Lycium barbarum L.) plants are still unclear. In this study, we conducted field and greenhouse experiments between 2019 and 2021, with 10 forage species as cover crops. We observed the growth, yield, fruit quality, and photosynthetic characteristics of wolfberry plants, as well as the occurrence of plant diseases and pests. Based on averaged data for all forage species, cover cropping facilitated plant growth, maintained fruit yield, and promoted leaf photosynthesis in wolfberry compared to monocropping. This was exemplified by a notable increase in the branch number of wolfberry plants under ryegrass treatment, with marginal increase in branch length under evergreen grass (lvyuan 5) and mangold treatments. Cover cropping additionally improved wolfberry quality through increasing carotenoid, flavonoid, and ascorbic acid contents by 21%, 53%, and 127%, respectively (P< 0.05). The presence of mangold, alfalfa, sweet sorghum, ryegrass, and feather grass reduced powdery mildew-induced leaf damage in wolfberry plants by 69% (P< 0.05). When alfalfa, feather grass, and ryegrass were used, the risk of aphid infestation was lowered by 67% (P< 0.05). Collectively, the results indicated that mangold, ryegrass, and alfalfa were the optimal cover crops for sustainable wolfberry production in the study area. The use of appropriate forage cover crops enhanced plant growth and fruit quality of wolfberry by stimulating photosynthetic capacity and biotic stress resistance.

Exploring selected bioinsecticides for management of cotton aphids (Aphis gossypii Glover) of brinjal in Bangladesh

Brinjal (Solanum melongena L.) is a popular vegetable in Bangladesh being nutritious, tasty, and cultivable throughout the year. Insect pests are the major constraint to its successful cultivation and production. The present study was conducted during the winter season when the sucking insect pests especially cotton aphids (Aphis gossypii Glover) are most abundant. Aphid infestation was observed in the brinjal plants since the early vegetative stage and sometimes the infestation rate reached up to 100 percent. Moreover, the infestation rate fluctuated with plants or duration. Aphids suck the cell saps resulting in stunting the growth of plants and yield reduction. As brinjal is consumed without peeling, contamination with toxic insecticides is a health concern. To address this, some bioinsecticides including abamectin preparation ‘Biomax M’, sodium lauryl ether sulphate preparation ‘Fizimite’, azadirachtin preparation ‘Fytomax’, Saccharopolyspora spinosa and Bacillus thuringiensis var. Kurstaki broth mixture preparation ‘Spinomax’, and potassium salt of fatty acid preparation ‘Fytoclean’ were selected to combat aphids. Besides, Voliam Flexi was applied as chemical control. A field study showed that abamectin preparation Biomax M was very potent against aphids showing zero percent aphid infestation. In addition, the chemical control Voliam Flexi 300 SC also provided zero percent aphid infestation. Therefore, Biomax M might be the non-toxic alternative to Voliam Flexi 300 SC for controlling aphids.