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Aphids (Hemiptera: Aphididae) are known for their remarkable adaptability and diversity, with most species richness found in temperate regions and worldwide distribution. Climate change is expected to affect aphid populations, especially their overwintering success. In this study, we aimed to investigate the diversity of wheat aphid populations and dynamics of overwintering success of aphids across early to late sown wheat. We employed both morphological and molecular techniques to distinguish and characterize six aphid species: Rhopalosiphum maidis, Rhopalosiphum rufiabdominalis, Rhopalosiphum padi, Sitobion avenae, Schizaphis graminum, and Metopolophium dirhodum. Among these, Rhopalosiphum maidis and Rhopalosiphum rufiabdominalis found to affect at the vegetative stage of the crop, while the other species were found to affect at the reproductive stage. Notably, we observed that aphid populations were more abundant on early-sown genotypes and decreased with normal and late sowing dates. The differences in peak aphid populations among different sowing dates revealed that delayed in sowing dates minimize aphid attack by producing asynchrony between host plant and the aphid population. Conversely, the environmental factors such as temperature, relative humidity, rainfall and bright sunshine hours varied across the sowing dates where early sown wheat genotypes are exposed to lower temperatures at vegetative stage and late sown genotypes are susceptible to higher temperatures at the terminal stage. These changes in environmental factors across different sowing dates affected the timing and duration of aphid life stages, including overwintering success. Nevertheless, understanding the diversity and distribution of aphid species in wheat crop and its response to different sowing dates could be crucial for developing effective pest management strategies, particularly in the context of climate change. Overall, this study highlights the need for ongoing aphid monitoring and adaptive management approaches that account for the dynamic interactions between pests, crops and the environment. [ABSTRACT FROM AUTHOR]

Rhopalosiphum padi L. is one of the most devastating cereal aphids in the world. Its feeding does not induce a clear phytotoxic response in plants. Little information is available on defence response triggered by R. padi feeding on wild wheats, frequently used to improve hexaploid wheat. An attempt has been made to understand the differential biochemical and molecular responses of R. padi feeding on moderately resistant and susceptible Aegilops tauschii genotypes. RNA‐Seq based transcriptomic analysis was conducted on 14 day‐old leaf tissues of moderately aphid resistant (R) genotype (Ae. tauschii pau14232) and susceptible (S) genotype (Ae. tauschii pau14138) infested with R. padi for 12, 24 and 48 h. Plant response to aphid infestation was comparatively faster in R genotype. A total of 10,589 genes were altered in R genotype in comparison to only 8068 differentially expressed genes (DEGs) in S genotypes. There was a gradual increase in significant DEGs from 12 to 48 h after R. padi infestation in R (4931–6582) and S genotype (4860–5736). Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed that 18 pathway genes were differentially expressed in R and S genotypes at different feeding time intervals. Gene ontology enrichment analysis of DEGs after R. padi feeding indicated up‐regulation of genes for secondary metabolite synthesis, reactive oxygen species (ROS)‐scavenging, transcription factors (ethylene responsive transcript factor [ERF], NAC, WRKY, MADS‐box and Myb) and salicylic acid and ethylene signalling pathways in R genotype while down‐regulation in S genotype. However, photosynthesis and light‐harvesting DEGs were down‐regulated in both the genotypes resulting in decreased chlorophyll content. Biochemical analysis showed that R. padi feeding induced substantial hydrogen peroxide accumulation in R genotype unlike in S genotype. Also, activities of peroxidase and catalase were comparatively higher in R than S genotype, confirming efficient ROS‐scavenging in R genotype. Quantitative polymerase chain reaction expression validation studies of 11 DEGs followed same trend as in RNA‐Seq data. Our study concluded up‐regulation of stress response genes, salicylate and ethylene signalling pathways and efficient ROS‐scavenging imparted a fitness advantage to R genotype during R. padi attack, resulting in reduced nymphiposition and nymphal survival. These findings will help in understanding the mechanism of host plant resistance and the development of aphid resistant wheat varieties. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Simple Summary: Endophytic fungi in pasture grasses help the plant resist unfavourable biotic and abiotic conditions. Despite some well-documented aspects of how these fungi confer resistance to insects, some mechanisms are not well known. In this work, we measured the effects of such endophytes on aphids, an important pest group. We measured aphid feeding activity and life-history effects to further understand the mode of action of endophyte–perennial ryegrass systems. We were able to demonstrate that, in some cases, fungal endophytes significantly deterred feeding, but in other cases, feeding was not affected, and yet high mortality was observed. This suggests a complex scenario of interactions between compounds in the endophyte–perennial-ryegrass–aphid system. Our study shows that fungal endophytes have the potential to improve sustainable aphid control by decreasing the use of insecticide sprays. The bird cherry-oat aphid, Rhopalosiphum padi (L.), is an economically significant pest of pasture grasses, the latter being capable of hosting several fungal endophyte–perennial ryegrass symbiota rich in alkaloids and toxic to vertebrates and invertebrates. Measuring aphid feeding behaviour can provide insights into the effectiveness and mode of action of different fungal endophytes. This study investigated the effects of different Epichloë–perennial ryegrass symbiota on the feeding behaviour of R. padi using the electrical penetration graph technique while also assessing the aphid life history. In most cases, endophytes had significant feeding deterrence and paired fecundity and mortality effects. But, in some instances, endophytes with the highest aphid mortality did not significantly deter feeding, suggesting a more complicated scenario of interactions between the relative concentration of metabolites, e.g., host plant defence response metabolites and alkaloids, and/or physical changes to leaf morphology. Overall, this study sheds light on the mode of action of Epichloë endophytes against aphids and highlights the importance of Epichloë–perennial ryegrass symbiota in the management of insect pests such as aphids in pasture-based grazing systems. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The search for natural product-based biopesticides from endophytic fungi is an effective tool to find new solutions. In this study, we studied a pre-selected fungal endophyte, isolate YCC4, from the paleoendemism Persea indica, along with compounds present in the extract and the identification of the insect antifeedant and nematicidal ones. The endophyte YCC4 was identified as Phyllosticta sp. by molecular analysis. The insect antifeedant activity was tested by choice bioassays against Spodoptera littoralis, Myzus persicae, and Rhopalosiphum padi, and the in vitro and in vivo mortality was tested against the root-knot nematode Meloidogyne javanica. Since the extract was an effective insect antifeedant, a strong nematicidal, and lacked phytotoxicity on tomato plants, a comprehensive chemical study was carried out. Two new metabolites, metguignardic acid (4) and (-)-epi-guignardone I (14), were identified along the known dioxolanones guignardic acid (1), ethyl guignardate (3), guignardianones A (5), C (2), D (7), and E (6), phenguignardic acid methyl ester (8), the meroterpenes guignardone A (9) and B (10), guignarenone B (11) and C (12), (-)-guignardone I (13), and phyllomeroterpenoid B (15). Among these compounds, 1 and 4 were effective antifeedants against S. littoralis and M. persicae, while 2 was only active on the aphid M. persicae. The nematicidal compounds were 4, 7, and 8. This is the first report on the insect antifeedant or nematicidal effects of these dioxolanone-type compounds. Since the insect antifeedant and nematicidal activity of the Phyllosticta sp. extract depend on the presence of dioxolanone components, future fermentation optimizations are needed to promote the biosynthesis of these compounds instead of meroterpenes. [ABSTRACT FROM AUTHOR]

Abstract As an important pest on winter wheat, Rhopalosiphum padi (L.) causes damage to the wheat yield by sucking plant nutrients, transmitting plant viruses and producing mildew. R. padi has been reported to develop resistance to pyrethroids and neonicotinoids. To explore potential alternative approaches for R. padi control, the activity of 10 botanical insecticides was evaluated. Results suggested that the toxicity of rotenone and pyrethrins to R. padi were the highest and near to the commonly used chemical insecticides. When exposed to the low-lethal concentrations (LC10, LC30) of rotenone or pyrethrins for 24 h, the lifespan and fecundity of adults in F0 generation decreased significantly compared to control. The negative effect could also be observed in the F1 generation, including the decreased average offspring, longevity of adult, and prolonged nymph period. The population parameters in F1 generation of R. padi were also inhibited by exposing to the low-lethal concentrations of rotenone or pyrethrins, including the decreased net reproductive rate, intrinsic rate of natural increase, finite rate of population increase, and gross reproduction rate. Co-toxocity factor results showed that mixtures of rotenone and thiamethoxam, pyrethrins and thiamethoxam showed synergistic effect. Our work suggested that rotenone and pyrethrins showed negative effect on the population growth under low-lethal concentrations. They are suitable for R. padi control as foliar spraying without causing population resurgence.

Symbiosis plays a critical role in plant biology. Temperate grasses often associate with several symbiotic fungi simultaneously, including Epichloë endophytes and arbuscular mycorrhizal (AM) fungi, in shoots and roots, respectively. These symbionts often modulate plant–herbivore interactions by influencing nutritional traits (i.e. AM fungi‐mediated nutrient uptake) and/or the secondary chemistry (i.e. endophytic alkaloids) of their host plant. Moreover, such grasses also accumulate large amounts of silicon (Si) from the soil, which can be deposited in tissues to act as a physical anti‐herbivore defence. Recent evidence suggests that both endophytes and AM fungi independently facilitate Si uptake. However, the consequences of their interactions with piercing‐sucking insects (i.e. aphids), or whether Si supply, endophytes, and AM fungi interact in this regard, are currently unknown. While Si deposition may be less effective against aphids than other herbivores (i.e. chewing caterpillars), Si supply can also alter plant secondary metabolite defences, which could affect sucking insects. In a factorial greenhouse experiment, we evaluated whether these components, acting alone or in combination, altered (1) foliar primary chemistry, (2) Si and symbiont‐chemical (endophytic alkaloids) defences, as well as (3) performance of the bird cherry‐oat aphid (Rhopalosiphum padi) feeding on tall fescue (Festuca arundinacea). Endophytes decreased all aphid performance parameters, including population growth and reproduction by 40%, but their impact was reversed by the presence of AM fungi, leading to a 52% increase in aphid performance compared with plants solely hosting endophytes. This improvement in performance was associated with reduced loline alkaloid levels and higher shoot nitrogen in AM‐endophytic plants. Endophytes and AM fungi exhibited antagonism, with endophytes reducing AM colonization by 34% and AM presence decreasing endophyte loline alkaloids by 44%. While both fungi jointly increased Si accumulation by 39% under Si‐supplied conditions, Si had no noticeable effects on aphids. Moreover, although Si supply had no identifiable effects on AM colonization, it reduced endophyte peramine alkaloids by 24%. Synthesis. Our findings indicate that symbiotic fungal partnerships and silicon provision may benefit plants but could weaken anti‐herbivore defences when combined. Revealing the complex interactions among diverse fungal symbionts and showcasing their effects on different anti‐herbivore defences (chemical and physical) and herbivore performance for the first time. [ABSTRACT FROM AUTHOR]

The bird cherry‐oat aphid (Rhopalosiphum padi) and the grain aphid (Sitobion miscanthi) are two destructive wheat pests that have caused severe economic losses in China's main wheat‐producing regions. Although previous studies have focused mainly on the population dynamics of wheat pests in wheat fields, little is known about the trans‐sea migration of both wheat aphid species in eastern China. Here, we conducted 10 years of monitoring from 2012 to 2021 to determine aerial migration patterns utilizing a suction trap on Beihuang Island (BH), a small island in the centre of the Bohai Strait that serves as a seasonal insect migratory pathway in eastern Asia. We also simulated the migration trajectories of these pests using the HYSPLIT model. Overall, a total of 6362 alatae S. miscanthi and 335 alatae R. padi were captured, and both wheat aphid species exhibited regular patterns of comigration across the sea from late April to late October each year. There were significant interannual and seasonal differences in the migratory numbers of both wheat aphids. Notably, the average daily humidity was the most important meteorological factor affecting migration biomass. The seasonal migration trajectories simulated using the HYSPLIT model revealed different source areas for both wheat aphid species, which mostly originated in Northeast, North and East China. Accordingly, our study provides valuable insights into the occurrence and migration route of wheat aphids in eastern Asia, helps fine‐tune forecasting and early warning systems, and thereby guides integrated pest management of wheat aphids in eastern Asia. [ABSTRACT FROM AUTHOR]

Survey and population densities of aphidophagous syrphid predators and their insect hyperparasitoids on maize plants infesting with aphids namely, Rhopalosiphum maidis (Fitch) and Rhopalosiphum padi (Linnaeus) at El-Deeb village, Abou-Kbeer district, Sharkia Governorate, Egypt were studied during 2022 and 2023 seasons. The obtained results were summarized as follow: six species of aphidophagous syrphid belonging to family Syrphidae namely, Xanthogramma aegyptium Wied., Sphaerophoria flavicauda Zett., Paragus aegyptius Macq., Paragus spp., Metasyrphus (=Syrphus) corollae (Fabr.) and Scaeva albomaculata Macq were surveyed on maize plants infesting with aphids. The total relative densities of the syrphid species were 34.17, 23.92, 18.54, 10.36, 7.22 and 5.79 % of the total number of hoverfly, successively. The total numbers of aphidophagous syrphid predators were fluctuated, showing a distinct peaks of 343 and 371 predators/sample in the 2nd and 3rd weeks of August during the first and second seasons, consecutively. The highest total monthly counts of 1016 and 1299 predators recorded in August during two successive seasons 2022 and 2023, consecutively. The means of syrphids : prey ratio were 1 : 28.76 and 1 : 22.59 during two successive seasons. Five species of hyperparasitoids belong to four families were recorded parasitized on syrphid species namely, Telenomus acrobats Giard, Telenomus sp. (Scelionidae), Diplazon laetatorius (Fabricius) (Ichneumonidae), Syrphophagus aphidivorus (Mayr) (Encyrtidae) and Tetrastichus sp. (Eulophidae), represented 25.43, 16.38, 25.43, 19.62 and 13.14% of the total collected hyperparasitoids, successively. The fluctuations of the total parasitoidism percentages recorded one and two peaks of activity during the first and second seasons, respectively. The mean percentages of parasitoidism during the second season was relatively low, 17.65 % in comparison with that in the first one (21.67%). The correlations between the total numbers of aphidophagous syrphid species and percentages of parasitodism were positive significant during two successive seasons. The periodic mean temperature and relative humidity affected syrphid species population by 55.27 and 62.57% during the 1st and 2nd seasons, respectively. Temperature and relative humidity affected percentages of parasitodism by 51.19 and 47.34 during the 1st and 2nd seasons, consecutively. Generally, the pesticides are not the only ones that affect on aphidophagous syrphid predators but the hyperparasitoids decrease the total numbers of the predators and negatively or harmfully affect their role in the biological control of aphid species in open felids and greenhouses. [ABSTRACT FROM AUTHOR]

Aphids are among the most economically significant pests in cereal crops worldwide. Despite high interest in the natural control of aphids by applying natural enemies, intercropping and companion planting, the concurrent effects of the combinations of these methods due to their synergistic or antagonistic interactions remain largely unknown for both aphids and their host crops. Here we identify the relative effectiveness of simultaneous bottom–up and top–down factors in controlling one of the most economically important species of cereal aphids, the bird cherry‐oat aphid Rhopalosiphum padi L. For this, we conducted microcosm experiments using a full‐factorial design of three aphid‐control treatments including predator presence (i.e., lacewing larvae of Chrysoperla carnea), host‐plant intercropping (i.e., barley alone vs barley in combination with wheat and rye) and companion planting with an aphid‐repellent plant (garlic), and estimated their direct, indirect and interactive effects on aphid density. Our results show strong simultaneous top–down control of the aphid population by predation and bottom–up control by both host‐plant biomass and companion planting with garlic. The use of garlic as a companion plant for cereal crops in our study neither altered crop biomass nor suppressed the efficiency of aphid predator. Our findings suggest that the simultaneous application of aphid predator and companion planting with garlic holds promise as a potential strategy for the natural control of cereal aphid populations on grain crops, without generating related agroecosystem disservices, such as loss in crop production and deterioration of the natural enemies of pests. However, given the controlled lab conditions and limited timeframe of our study, further research is needed to confirm its effectiveness in field conditions to ensure its broader applicability in sustainable agricultural practices. [ABSTRACT FROM AUTHOR]

Aphidius platensis Brèthes (Hymenoptera: Braconidae) is a parasitoid of cereal aphids. Its foraging, recognition, and host acceptance processes may be related to chemical cues inherited from the host during development. This study aimed to evaluate the influence of the maternal host, that is, Rhopalosiphum padi (L.) (Rp), Schizaphis graminum (Rondani) (Sg) (from the Aphidini tribe), Metopolophium dirhodum Walker (Md), and Sitobion avenae (Fabricius) (Hemiptera: Aphididae) (from the Macrosiphini tribe) (all Hemiptera: Aphididae) on parasitism and chemotactic responses of A. platensis. Parasitism by A. platensis was investigated in non‐choice bioassays along four generations, as well as in choice bioassays. Females originating from a S. graminum laboratory colony (SgLab) were reared for four generations on all four aphid species. Chemotaxis experiments were conducted in a four‐armed olfactometer with two A. platensis strains: one originated from SgLab and another after three generations on Rp (RpF4), both exposed to the four aphid species simultaneously. The highest SgLab A. platensis parasitism rates, in both choice and non‐choice tests, were observed on S. graminum, followed by R. padi and S. avenae. No parasitized hosts were found in M. dirhodum. Furthermore, SgLab A. platensis exhibited a stronger attraction to the odors emitted by S. graminum. However, after the third generation on R. padi (RpF4), A. platensis behavior altered, displaying a preference for R. padi over S. graminum, both in terms of parasitism and chemotactic responses. In conclusion, A. platensis showed a preference for hosts within the Aphidini tribe, indicating innate affinities. Nevertheless, its preference can be modified within this tribe based on the chemical cues inherited from the host during development. [ABSTRACT FROM AUTHOR]

Background: Wheat is considered one of the primary and strategic grain crops in the world in terms of production and importance. The increment in both quantity and quality of wheat production renders it susceptible to various pests and diseases, including both insects and non-insect pests. The study aims to study the extent of infection of the IPA 99, IPA 22 and Abu Ghraib wheat varieties with aphids. Methods: A general survey of aphids on Abu Ghraib, IPA 99 and IPA 22 wheat varieties was carried out in the fields of the College of Agriculture/ University of Baghdad in Abu Ghraib during the growing season 2021-2022. Result: The results of the field survey indicated the presence of three species of aphids on the wheat crops belonging to the order Hemiptera and the family Aphididae: the wheat aphid [Schizaphis graminum (Rondani)], the oat aphid [Rhopalosiphum padi (L.)] and the corn aphid (Rhopalosiphum maidis). Wheat and oat aphids were the most commonly found on the crops. The presence of aphids on the plants was affected by the predominant environmental conditions like temperature, humidity, the chemical components of the host plants and the interactions between these factors. Additionally, we identified one type of predator belonging to the order of Coleoptera, the seven-spotted ladybug (Coccinella septempunctata), which was observed to be affected by the pest density. Aphids are a major pest of wheat in Iraq and they can cause significant losses of crops if their population is not controlled. [ABSTRACT FROM AUTHOR]

Many aphid species exhibit both cyclical parthenogenesis (CP) and the obligate parthenogenesis (OP) life history, which are genetically determined. In CP aphid lineages, the parthenogenetic individuals can switch from asexual to sexual reproduction quickly in response to environmental factors such as changes in photoperiod and temperature. However, the OP aphid lineages do not undergo sexual reproduction under any conditions. So far, mechanisms underlying the reproduction switch in CP aphids have not been fully elucidated. Rhopalosiphum padi, a serious worldwide insect pest of wheat, has both CP and OP lineages. Uridine diphosphate‐glycosyltransferases (UGTs) are enzymes that participate in the metabolic detoxification of xenobiotics. Here, we identified 43 RpUGT genes from R. padi genome and transcriptome sequences, and found that: (1) the UGT content of the CP lineage was significantly higher than that in the OP lineage at the key time points when CP lineage mainly produce virginoparae, gynoparae, and males under inducing condition, while there were no significant difference under normal conditions; (2) RpUGT344J7 gene was highly expressed during the time points when CP lineages produce gynopara and males; (3) the critical time points for CP lineages to produce virginoparaee, gynoparae, and males were affected when the CP lineages were injected with dsRpUGT344J7; (4) the knockdown of RpUGT344J7 caused a significant reduction in the total number of virginoparae, gynoparae, and males in the offspring under inducing condition. The findings contribute to our understanding of the molecular mechanisms underlying the quick shift from asexual to sexual reproduction in aphid species. [ABSTRACT FROM AUTHOR]

A trade‐off between growth and defence against biotic stresses is common in plants. Fungal endophytes of the genus Epichloë may relieve this trade‐off in their host grasses since they can simultaneously induce plant growth and produce antiherbivore alkaloids that circumvent the need for host defence. The Epichloë ability to decouple the growth‐defence trade‐off was evaluated by subjecting ryegrass with and without Epichloë endophytes to an exogenous treatment with gibberellin (GA) followed by a challenge with Rhopalosiphum padi aphids. In agreement with the endophyte‐mediated trade‐off decoupling hypothesis, the GA‐derived promotion of plant growth increased the susceptibility to aphids in endophyte‐free plants but did not affect the insect resistance in endophyte‐symbiotic plants. In line with the unaltered insect resistance, the GA treatment did not reduce the concentration of Epichloë‐derived alkaloids. The Epichloë mycelial biomass was transiently increased by the GA treatment but at the expense of hyphal integrity. The response of the phyllosphere bacterial microbiota to both GA treatment and Epichloë was also evaluated. Only Epichloë, and not the GA treatment, altered the composition of the phyllosphere microbiota and the abundance of certain bacterial taxa. Our findings clearly demonstrate that Epichloë does indeed relieve the plant growth‐defence trade‐off. Summary statement: A debate has been raised if fungal endophytes can relieve the plant growth‐defence trade‐off. Epichloë endophytes decoupled the trade‐off: the growth‐mediated penalisation of plant defences was observed in E− but not in E+ plants. The Epichloë production of alkaloids was likely the decoupling mechanism. [ABSTRACT FROM AUTHOR]

Abstract—Using the next-generation sequencing (NGS) technology, the nucleotide polymorphism in a fragment of the ND4 gene encoding NADH dehydrogenase subunit 4 was studied in 14 samples from three populations of the bird cherry-oat aphid (Rhopalosiphum padi L.) and the range of nucleotide polymorphism was determined. The insects were collected in 2021 and 2022 in the Northwest of Russia (in the vicinity of St. Petersburg) and in the northern Caucasus (Krasnodar Territory and Dagestan). Mitochondrial DNA haplotypes were identified, which have 97.95–99.80% sequence identity with the reference GenBank accession number KT447631.1. The level of intraspecific polymorphism of a 438 bp ND4 gene fragment in Rh. padi varied from 0.2 to 4.3%. In 2-year experiments, 33 polymorphic sites (17 transitions and 16 transversions) were found in the ND4 sequences, which made it possible to identify 30 mitochondrial DNA haplotypes. The Rh. padi populations collected simultaneously on different host plants or at different times on bird cherry (spring) and cereals (summer) differed in the proportion of the main haplotype, as well as in the composition of unique minor haplotypes. Analysis of the ratio of mitochondrial DNA haplotypes suggests the important role of the host plant genotype in the formation of the structure of Rh. padi populations. [ABSTRACT FROM AUTHOR]

Aphids (Hemiptera: Aphidoidea) are economically important crop pests worldwide. Because of growing issues with insecticide resistance and environmental contamination by insecticides, alternate methods are being explored to provide aphid control. Aphids contain endosymbiotic bacteria that affect host fitness and could be targeted as potential biocontrol agents, but such novel strategies should not impact the effectiveness of traditional chemical control. In this work, we used a novel endosymbiont transinfection to examine the impact of the endosymbiont Rickettsiella viridis on chemical tolerance in 3 important agricultural pest species of aphid: Myzus persicae (Sulzer) (Hemiptera: Aphididae) , Rhopalosiphum padi (Linnaeus) (Hemiptera: Aphididae), and Diuraphis noxia (Mordvilko ex Kurdjumov) (Hemiptera: Aphididae). We tested tolerance to the commonly used insecticides alpha-cypermethrin, bifenthrin, and pirimicarb using a leaf-dip bioassay. We found no observed effect of this novel endosymbiont transinfection on chemical tolerance, suggesting that the strain of Rickettsiella tested here could be used as a biocontrol agent without affecting sensitivity to insecticides. This may allow Rickettsiella transinfections to be used in combination with chemical applications for pest control. The impacts of other endosymbionts on insecticide tolerance should be considered, along with tests on multiple aphid clones with different inherent levels of chemical tolerance. [ABSTRACT FROM AUTHOR]

As an important pest on winter wheat, Rhopalosiphum padi (L.) causes damage to the wheat yield by sucking plant nutrients, transmitting plant viruses and producing mildew. R. padi has been reported to develop resistance to pyrethroids and neonicotinoids. To explore potential alternative approaches for R. padi control, the activity of 10 botanical insecticides was evaluated. Results suggested that the toxicity of rotenone and pyrethrins to R. padi were the highest and near to the commonly used chemical insecticides. When exposed to the low-lethal concentrations (LC10, LC30) of rotenone or pyrethrins for 24 h, the lifespan and fecundity of adults in F0 generation decreased significantly compared to control. The negative effect could also be observed in the F1 generation, including the decreased average offspring, longevity of adult, and prolonged nymph period. The population parameters in F1 generation of R. padi were also inhibited by exposing to the low-lethal concentrations of rotenone or pyrethrins, including the decreased net reproductive rate, intrinsic rate of natural increase, finite rate of population increase, and gross reproduction rate. Co-toxocity factor results showed that mixtures of rotenone and thiamethoxam, pyrethrins and thiamethoxam showed synergistic effect. Our work suggested that rotenone and pyrethrins showed negative effect on the population growth under low-lethal concentrations. They are suitable for R. padi control as foliar spraying without causing population resurgence. [ABSTRACT FROM AUTHOR]

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Global warming is affecting the severity of yield losses due to increased pest abundances. However, few studies have investigated how warming may affect interspecific competitions in multi-pest systems. Here, we investigated the effects of a 2 °C temperature increase on the population growth and distribution on plants of the aphids Rhopalosiphum padi and Sitobion avenae in single versus mixed species releases. We also investigated how the distribution of aphids across plant parts (lower leaves, upper leaves and stems) could be explained by plant tissue content in soluble sugars, free amino acids and flavonoids and by plant tissue microenvironment (leaf temperature and water potential). Populations of R. padi were higher under increased temperature, which caused increased competition on S. avenae. This in turn decreased S. avenae's niche breadth under increased temperature. Contents in soluble sugar, free amino acids and flavonoids were higher in lower and upper leaves compared to stems, but were not affected by temperature. The number of aphids in different plant parts was strongly and negatively correlated with plant tissue water potential, an indicator of reduced content in flavonoids and soluble sugars. Our study shows that even relatively small increases in temperature reflecting climate change may disturb species interactions notably through plant-mediated effects, but consequences for crop productivity are difficult to predict. [ABSTRACT FROM AUTHOR]

Plant volatiles play an important role in intra‐ and interspecific plant communication, inducing direct and indirect defenses against insect pests. However, it remains unknown whether volatile interactions between undamaged cultivars alter host plant volatile emissions and their perception by insect pests. Here, we tested the effects of exposure of a spring barley, Hordeum vulgare L., cultivar, Salome, to volatiles from other cultivars: Fairytale and Anakin. We found that exposing Salome to Fairytale induced a significantly higher emission of trans‐β‐ocimene and two unidentified compounds compared when exposed to Anakin. Aphids were repelled at a higher concentration of trans‐β‐ocimene. Salome exposure to Fairytale had significant repulsive effects on aphid olfactory preference, yet not when Salome was exposed to Anakin. We demonstrate that volatile interactions between specific undamaged plants can induce changes in volatile emission by receiver plants enhancing certain compounds, which can disrupt aphid olfactory preferences. Our results highlight the significant roles of volatiles in plant–plant interactions, affecting plant–insect interactions in suppressing insect pests. This has important implications for crop protection and sustainable agriculture. Summary statement: The airborne interactions between certain undamaged spring barley (Hordeum vulgare L.) cultivars induce changes in volatile emission in receiving plants by enhancing the production of certain ideal volatile organic compounds. These changes trigger strong repellent effects on aphids (Rhopalosiphum padi L.), suggesting the significant roles of volatile‐mediated plant–plant interactions in the development of integrated pest management for sustainable agriculture practices. [ABSTRACT FROM AUTHOR]

Hesperidin is a highly bioactive natural flavonoid whose role in ecological interactions is poorly known. In particular, the effects of hesperidin on herbivores are rarely reported. Flavonoids have been considered as prospective biopesticides; therefore, the aim of the present study was to examine the influence of hesperidin on the host plant selection behavior of three aphid (Hemiptera: Aphididae) species: Acyrthosiphon pisum Harrris, Rhopalosiphum padi (L.), and Myzus persicae (Sulz.). The aphid host plants were treated with 0.1% and 0.5% ethanolic solutions of hesperidin. Aphid probing behavior in the no-choice experiment was monitored using electropenetrography and aphid settling on plants in the choice experiment was recorded. The results demonstrated that hesperidin can be applied as a pre-ingestive, ingestive, and post-ingestive deterrent against A. pisum, as an ingestive deterrent against R. padi, and as a post-ingestive deterrent against M. persicae using the relatively low 0.1% concentration. While in A. pisum the deterrent effects of hesperidin were manifested as early as during aphid probing in peripheral plant tissues, in M. persicae, the avoidance of plants was probably the consequence of consuming the hesperidin-containing phloem sap. [ABSTRACT FROM AUTHOR]

Climate change may have diverse and complex impacts on species interactions, destabilizing food webs and ecosystem services. The effects of warming on the top‐down biological control of crop pests have been considerably less studied than bottom‐up effects through crop physiological changes.We studied the effect of a 2°C warming in the laboratory and in wheat fields on the predation and metabolism of Harmonia axyridis on wheat aphids using molecular gut content analysis. We also measured the effects of warming on the predation rate and functional response of H. axyridis on each aphid species in the laboratory, as well as on DNA degradation rate.Field densities of Sitobion avenae and Rhopalosiphum padi, the two most abundant wheat aphid species, were increased by 2 and 2.5 times, respectively, under experimental warming, but densities of H. axyridis were not. Field predation rate of H. axyridis on these two aphid was found to be about 25% lower under elevated temperature. This could have been due to faster prey digestion, since degradation of the preferred aphid species, Sitobion avenae, was 1.5 times faster under elevated temperature. However, the functional response of H. axyridis larvae on these two species was 1.5 times higher under warming over the range of prey densities tested (50–250 over 24 h). The total predation rate of H. axyridis larvae on a mixture of S. avenae, R. padi and Schizaphis graminum aphid prey was also increased by 1.4 times, but consumption of R. padi aphids was increased while that of S. graminum was decreased under warming.Overall, our results show that global warming could strongly increase pest outbreaks and destabilize biological pest control, which would likely result in accrued yield losses. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Unlike European species, the potential of Nearctic syrphids as biological control agents is still poorly studied. However, the American hoverfly, Eupeodes americanus (Wiedemann), has recently demonstrated promising traits as a biocontrol agent, notably against the foxglove aphid, Aulacorthum solani Kaltenbach, on pepper. The present study aims to extend our knowledge of the American hoverfly by evaluating its potential as a biocontrol agent in a banker plant system against the melon aphid, Aphis gossypii Glover, in a greenhouse cucumber crop. The preimaginal development and voracity of E. americanus were compared when preying upon the focal prey/pest (A. gossypii) or the banker prey (bird cherry‐oat aphid, Rhopalosiphum padi L.) by daily observations of larvae from egg to adult. Preimaginal development time, survival rate, and occurrence of deformation were similar on both prey species. The weight of third instar and pupae, however, was higher for larvae that fed on the banker prey. The ad libitum voracity of the syrphid larvae was generally very high and did not significantly differ between prey species, except for the third‐instar larvae which consumed more focal prey. Results suggest that a banker plant system involving the bird cherry‐oat aphid may be a promising tactic for utilizing E. americanus for melon aphid biocontrol. [ABSTRACT FROM AUTHOR]

Essential oils (EOs), including those from the Asteraceae plants, have been shown to have promising insecticidal activity against a wide range of insect pests. Understanding the mechanism of action of EOs is one of the studied aspects. The present study aimed to evaluate the effect of essential oils from Achillea millefolium, Santolina chamaecyparissus, Tagetes patula and Tanacetum vulgare on the settling and probing behavior of the bird cherry-oat aphid (Rhopalosiphum padi L.). In addition, the effect of the oils on the activity of such enzymes as trypsin, pepsin and α- and β-glucosidase involved in the metabolism of proteins and sugars of the insects was examined. The leaf-choice bioassays demonstrated that the studied EOs limited aphid settling for at least 24 h after the treatment. The application of EOs also inferred with aphid probing behavior by reducing the total probing time and total duration of phloem sap ingestion. Aphids spent more time in the search phase due to an increase in the number and total duration of pathway phases. Moreover, the activity of the studied proteases and glucosidases significantly decreased in R. padi females exposed to the EOs. The enzyme inhibition varied depending on the applied oil and exposure time. Generally, the EOs with stronger deterrent activity also showed higher inhibitory effects. The results suggest that the tested EOs disrupt key digestive processes in R. padi which may be an important factor determining their aphicidal activity. [ABSTRACT FROM AUTHOR]

Thiamethoxam, a second-generation neonicotinoid insecticide is widely used for controlling sap-sucking insect pests including Rhopalosiphum padi. The current study aimed to investigate the life-history parameters and feeding behavior of R. padi following treatments with sublethal concentrations of thiamethoxam. The lethal concentration 50 (LC50) value of thiamethoxam against adult R. padi was 11.458 mg L−1 after 48 h exposure. The sublethal concentrations of thiamethoxam (LC5 and LC10) significantly decreased the adult longevity, fecundity, and reproductive days in the directly exposed aphids (F0 generation). In the progeny R. padi (F1), the developmental durations and total prereproductive period (TPRP) were decreased while the adult longevity, fecundity, and reproductive days (RPd) were increased at both thiamethoxam concentrations. The demographic parameters including the net reproductive rate (R0), intrinsic rate of increase (r), and finite rate of increase (λ) were prolonged only at the LC5 of thiamethoxam. The EPG results indicated that the sublethal concentrations of thiamethoxam increases the total duration of non-probing (Np) while reducing the total duration of E2 in directly exposed aphids (F0). Interestingly, the E2 were significantly increased in the progeny generation (F1) descending from previously exposed parental aphids (F0). Overall, this study showed that thiamethoxam exhibited high toxicity against directly exposed individuals (F0), while inducing intergenerational hormetic effects on the progeny generation (F1) of R. padi. These findings provided crucial details about thiamethoxam-induced hormetic effects that might be useful in managing resurgences of this key pest. [ABSTRACT FROM AUTHOR]

Wheat aphids are major pests of wheat and a significant threat to global food security. Eupeodes corollae Fabricius is one of the dominant species of wheat field hoverflies, but its ability and role in wheat aphid control lack systematic research. This study on the predatory function responses of E. corollae to Rhopalosiphum padi Linnaeus, Schizaphis graminum Rondani, and Sitobion miscanthi, Takahashi showed that the maximum daily predation (1/Th) of 2nd instar E. corollae larvae was 166.67, 125.00, and 142.86, and that of 3rd instar larvae was 333.33, 250.00, and 250.00, respectively. The cage simulation test indicated that the wheat aphid population decline rate was 100% at the 60th hour of inoculation of 3rd instar E. corollae larvae at a 1:100 ratio. Eupeodes corollae exhibited a predatory relationship with all three wheat aphid species in the wheat fields of Hebei Province, China, and the corrected predation detection rates of E. corollae larvae against R. padi, S. graminum, and S. miscanthi were 12.36%, 1.08%, and 28.77% in 2022, and 6.74%, 0.82%, and 37.56% in 2023, respectively. The results of this study clarify the predatory ability of E. corollae on wheat aphids and the predatory relationship between them and provide technical support for the management of wheat aphids using the bio-control ecological service function of E. corollae. [ABSTRACT FROM AUTHOR]

Wheat (Triticum aestivum L.) is the major global staple food crop that meets the food security demands of various nations across the continents. The recent reduction in wheat production is attributed to several biotic and abiotic factors especially, temperature and rainfall patterns, and pest occurrence. Among insect pests, aphid species are emerging as new pests of economic importance in India and elsewhere. The present investigation identified a new association of Macrosiphum euphorbiae Thomas with the wheat crop. Life table parameters were studied for M. euphorbiae and Rhopalosiphum padi fed on wheat foliage. The total nymphal duration and life cycle duration, respectively, of R. padi (4.76 ± 0.54 and 9.71 ± 1.38 days) and M. euphorbiae (5.84 ± 0.69 and 9.96 ± 1.31 days) were significantly different for these species. The fecundity of the two aphid species was 23.95 ± 8.67 and 11.6 ± 4.10 progeny/female, respectively. Age-specific survival rate (lx), age-specific fecundity (fx), and population age-specific fecundity (mx) were higher in R. Padi compared to M. euphorbiae. Reproductive value (Vxj) was high in R. padi and the duration of reproduction was less, while these parameters showed an opposite trend in M. euphorbiae. The gross reproduction rate (GRR) was found higher in R. Padi (29.17 offspring/adult lifetime) compared to M. euphorbiae (19.58 offspring/adult lifetime). The M. euphorbiae being a pest of solanaceous crops seems to have shifted to a new host, i.e., wheat. This new adaptation strategy to survive for long periods on a wheat crop might pose a serious threat to wheat crop cultivation in near future. [ABSTRACT FROM AUTHOR]

Bats are widely distributed in Brazil, including the Amazon region, and their association with viral pathogens is well-known. This work aimed to evaluate the metavirome in samples of Molossus sp. bats captured in the Brazilian Amazon from 2019 to 2021. Lung samples from 58 bats were divided into 13 pools for RNA isolation and sequencing followed by bioinformatic analysis. The Retroviridae family showed the highest abundance of viral reads. Although no complete genome could be recovered, the Paramyxoviridae and Dicistroviridae families showed the formation of contigs with satisfactory identity and size characteristics for further analysis. One contig of the Paramyxoviridae family was characterized as belonging to the genus Morbillivirus, being grouped most closely phylogenetically to Porcine morbillivirus. The contig related to the Dicistroviridae family was identified within the Cripavirus genus, with 94%, 91%, and 42% amino acid identity with Culex dicistrovirus 2, Rhopalosiphum padi, and Aphid lethal paralysis, respectively. The presence of viruses in bats needs constant updating since the study was able to identify viral sequences related to families or genera still poorly described in the literature in association with bats. [ABSTRACT FROM AUTHOR]

Plant volatile organic compounds (VOCs) are the key distress signals involved in tritrophic interactions, by which plants recruit predators to protect themselves from herbivores. However, the effect of nitrogen fertilization on VOCs that mediate tritrophic interactions remains largely unidentified. In this study, a maize (Zea mays)-aphid (Rhopalosiphum padi)-ladybird (Harmonia axyridis) tritrophic interaction model was constructed under high-nitrogen (HN) and low-nitrogen (LN) regimens. H. axyridis had a stronger tendency to be attracted by aphid-infested maize under HN conditions. Then, volatiles were collected and identified from maize leaves on which aphids had fed. All of the HN-induced volatiles (HNIVs) elicited an electroantennogram (EAG) response from H. axyridis. Of these HNIVs, 1-nonene was attractive to H. axyridis under simulated natural volatilization. Furthermore, our regression showed that the release of 1-nonene was positively correlated with H. axyridis visitation rates. Supplying 1-nonene to maize on which aphids had fed under LN enhanced attractiveness to H. axyridis. These results supported the conclusion that 1-nonene was the active compound that mediated the response to nitrogen in the tritrophic interaction. In addition, the 1-nonene synthesis pathway was hypothesized, and we found that the release of 1-nonene might be related to the presence of salicylic acid (SA) and abscisic acid (ABA). This research contributes to the development of novel environmentally friendly strategies to optimize nitrogen fertilizer application and to improve pest control in maize crops. [ABSTRACT FROM AUTHOR]

The barley yellow dwarf virus (BYDV) of cereals is thought to substantially increase the high-temperature tolerance of its aphid vector, Rhopalosiphum padi, which may enhance its transmission efficiency. This is based on experiments with North American strains of BYDV and R. padi. Here, we independently test these by measuring the temperature tolerance, via Critical Thermal Maximum (CTmax) and knockdown time, of Australian R. padi infected with a local BYDV isolate. We further consider the interaction between BYDV transmission, the primary endosymbiont of R. padi (Buchnera aphidicola), and a transinfected secondary endosymbiont (Rickettsiella viridis) which reduces the thermotolerance of other aphid species. We failed to find an increase in tolerance to high temperatures in BYDV-infected aphids or an impact of Rickettsiella on thermotolerance. However, BYDV interacted with R. padi endosymbionts in unexpected ways, suppressing the density of Buchnera and Rickettsiella. BYDV density was also fourfold higher in Rickettsiella-infected aphids. Our findings indicate that BYDV does not necessarily increase the temperature tolerance of the aphid transmission vector to increase its transmission potential, at least for the genotype combinations tested here. The interactions between BYDV and Rickettsiella suggest new ways in which aphid endosymbionts may influence how BYDV spreads, which needs further testing in a field context. [ABSTRACT FROM AUTHOR]

The very early emergence of the vectors of potato virus poses a very serious risk to the phytosanitary quality of potatoes and for that their monitoring is very important in anticipating their maximum flight. To monitor the flight dynamics of aphid species with vector capacity in seed potato crops, in 2020-2022 at Brasov, 3 yellow water traps placed at different distances from the potato field edge and a 12.2 m high suction trap were used to capture flying aphids. 22 vector aphid species were selected from the catches of the two types of traps; their flight was analyzed in relation to the climatic data from the years of monitoring. Some of the dominant and eudominant virotic vectors (Aphis fabae, Brachycaudus helichrysi, Rhopalosiphum padi, Myzus persicae, Hyalopterus pruni, Aphis sambuci, Phorodon humuli, Aphis craccivora) started their activity, from the first decade of May and their maximum flight was different from one species to another and from one climatic year to another. The suction trap was an efficient tool in capturing vector aphids, in order to monitor their flight. [ABSTRACT FROM AUTHOR]

The chemical composition, insect antifeedant, in vtro/in vivo nematicidal activity, phytotoxicity, and in silico nematicidal activity of the essential oil (EO) of the African medicinal plant Drypetes gossweileri were studied. Chemical analysis using GC/MS indicated that benzyl isothiocyanate (96.23%) was the major compound, followed by benzyl cyanide (1.38%). The biocidal effects of this oil were tested against insect pests and root-knot nematodes. All the insect species tested were significantly affected by the oil according to their feeding adaptations (Spodoptera littoralis and Myzus persicae were less affected than Rhopalosiphum padi) with efficient doses (EC50) of 29.4 8.3 mg/cm2, 14.744 8.3 mg/cm², and 8.3 mg/cm2 , respectively. The oil was highly effective against juveniles J2 of the nematode Meloidogyne javanica, with LC50–LC90 values of 0.007 mg/mL–0.0113 mg/mL. D. gossweileri EO at minimum lethal concentrations (MLC) and below strongly inhibited egg hatching in vitro, whereas soil treatment caused a strong suppression of nematode population, infection frequency, and multiplication rate. The EO inhibited ryegrass (Lolium perenne) germination at 0.4 mg/mL, while at 0.1 mg/mL, its effects on germination, root and leaf growth were moderate (32.4%, 8.4%, and 18.3%, respectively). The tomato (Solanum lycopersicum) germination was not affected by the EO, but the root growth was reduced (56% at 0.1 mg/mL) at a dose 10 times higher than the LD50 calculated for M. javanica J2 mortality. Molecular docking of the nematicidal effects of the oil using PyRx revealed a strong interaction between potassium chloride transporting KCC3 (PDB ID: 7D90) and benzyl cyanide at a distance of 2.20 A° with GLN C:350, followed by benzyl isothiocyanate at a distance of 2.78 A° with ARG B:294. The in vivo nematicidal effects of D. gossweileri EO on M. javanica penetration and reproduction in tomato roots further support the potential of this EO as a nematicidal agent with insect antifeedant effects, which could be used by local farmers for crop protection. [ABSTRACT FROM AUTHOR]

Bacillus subtilis 26D is a plant growth-promoting endophytic bacteria capable of inducing systemic resistance through the priming mechanism, which includes plant genome reprogramming and the phenomenon of RNA interference (RNAi) and microRNA (miRNAs). The phloem-feeding insect bird cherry-oat aphid Rhopalosiphum padi L. is a serious pest that causes significant damage to crops throughout the world. However, the function of plant miRNAs in the response to aphid infestation remains unclear. The results of this work showed that B. subtilis 26D stimulated aphid resistance in wheat plants, inducing the expression of genes of hormonal signaling pathways ICS, WRKY13, PR1, ACS, EIN3, PR3, and ABI5. In addition, B. subtilis 26D activated the RNAi mechanism and regulated the expression of nine conserved miRNAs through activation of the ethylene, salicylic acid (SA), and abscisic acid (ABA) signaling pathways, which was demonstrated by using treatments with phytohormones. Treatment of plants with SA, ethylene, and ABA acted in a similar manner to B. subtilis 26D on induction of the expression of the AGO4, AGO5 and DCL2, DCL4 genes, as well as the expression of nine conserved miRNAs. Different patterns of miRNA expression were found in aphid-infested plants and in plants treated with B. subtilis 26D or SA, ethylene, and ABA and infested by aphids, suggesting that miRNAs play multiple roles in the plant response to phloem-feeding insects, associated with effects on hormonal signaling pathways, redox metabolism, and the synthesis of secondary metabolites. Our study provides new data to further elucidate the fine mechanisms of bacterial-induced priming. However, further extensive work is needed to fully unravel these mechanisms. [ABSTRACT FROM AUTHOR]

Imidacloprid is a neonicotinoid insecticide that efficiently controls piercing-sucking mouthparts pests. However, the impact of low lethal concentration of imidacloprid on key demographic parameters of wheat aphids, Schizaphis graminum (R.) and Rhopalosiphum padi (L.) has been scarcely studied. In this study, we used the age stage, two-sex life table approach to investigate the sublethal effects of imidacloprid on the biological traits of S. graminum and R. padi. Bioassays showed that imidacloprid possesses high toxicity to adult S. graminum and R. padi, with LC50 of 3.59 and 13.78 mg L−1 following 24 h exposure. A low lethal concentration of imidacloprid (LC25) significantly decreased adult longevity and total longevity of progeny generation aphids (F1) of S. graminum. Nevertheless, imidacloprid (LC25) had no significant effects on the fecundity and longevity of directly exposed parental parental S. graminum and R. padi (F0). Our results showed that the low lethal concentration of imidacloprid affected the demographic parameters that ultimately impact on the population of S. graminum. This study provides detailed information about the overall effects of imidacloprid on S. graminum and R. padi that might help to manage these two key pests. [ABSTRACT FROM AUTHOR]

A walnut–wheat intercropping pattern is practiced widely in southern Xinjiang to alleviate the contradiction between the lack of cultivated land resources and to increase economic value. Previous studies have confirmed that an alley cropping pattern could change the microclimate by supplying additional ecological functions such as windbreak, light interception, water conservation, etc. Cereal aphids (including Sitobion avenae, Rhopalosiphum padi, Metopolophium dirhodum, etc.) are commonly spread pests that harm wheat plants. But, the difference in population numbers between local patterns is still unknown. Pesticide reduction is the national strategy in China to alleviate the contraction between the demand of grain yield and environment protection. Plant protection-unmanned aerial vehicles (UAV) spraying pesticides are the most efficient method to control pests. However, compared to traditional artificial spraying method, how the UAV spraying method affect the control effect of reduced concentration pesticide is unclear. In order to address this problem, we conducted field investigations at Zepu county in southern Xinjiang to test the difference between walnut–wheat intercropping and wheat monocropping patterns for three consecutive years. And, we employed the field experiments to ensure the effectiveness of the reduced concentration common pesticides through the UAV spraying method. In conclusion, we conducted a comparison of the control effects of two spraying methods under conditions of reduced pesticide usage. Our findings revealed that the population of cereal aphids was larger in the intercropping pattern compared to the monocropping pattern. Although the control effect of the reduced treatment was lower than the regular dosage, some treatments still demonstrated sufficient capability to eliminate aphids, particularly when considering the effect within major varieties. Additionally, the use of the UAV spraying method exhibited a satisfactory effect when compared to the traditional artificial spraying method. [ABSTRACT FROM AUTHOR]

The bird cherry-oat aphid, Rhopalosiphum padi (L.) (Hemiptera: Aphididae) is one of the most economically important pests of wheat crops worldwide. Thiamethoxam, bifenthrin, and flonicamid are extensively used insecticides for controlling this key pest. However, the indiscriminate use of chemical insecticides has led to the development of resistance in insects. In this study, we assessed the development of selection-induced resistance to bifenthrin, flonicamid, and thiamethoxam under controlled laboratory conditions. Additionally, we employed the age-stage, two-sex life table method to examine the fitness of R. padi. After ten generations of selection, bifenthrin-, flonicamid-, and thiamethoxam-resistant strains of R. padi were developed with resistance levels of 34.46, 31.97, and 26.46-fold, respectively. The life table analysis revealed a significant decrease in adult longevity and fecundity in these resistant strains compared to susceptible strain. Furthermore, the key demographic parameters such as net reproductive rate (R0) and reproductive days exhibited a significant reduction in all resistant strains, while the intrinsic rate of increase (r) and finite rate of increase (λ) were decreased only in resistant strains to bifenthrin and thiamethoxam. Taken together, these findings provide a comprehensive understanding of laboratory-induced insecticide resistance evolution and the associated fitness costs in R. padi. This knowledge could help to design resistance management strategies against this particular pest of wheat. [ABSTRACT FROM AUTHOR]

Rhopalosiphum padi is an important global wheat pest. The pyrethroid insecticide bifenthrin is widely used in the control R. padi. We explored the resistance potential, cross-resistance, adaptive costs, and resistance mechanism of R. padi to bifenthrin using a bifenthrin-resistant strain (Rp-BIF) established in laboratory. The Rp-BIF strain developed extremely high resistance against bifenthrin (1033.036-fold). Cross-resistance analyses showed that the Rp-BIF strain had an extremely high level of cross-resistance to deltamethrin (974.483-fold), moderate levels of cross-resistance to chlorfenapyr (34.051-fold), isoprocarb (27.415-fold), imidacloprid (14.819-fold), and thiamethoxam (11.228-fold), whereas negative cross-resistance was observed to chlorpyrifos (0.379-fold). The enzymatic activity results suggested that P450 played an important role in bifenthrin resistance. A super-kdr mutation (M918L) of voltage-gated sodium channel (VGSC) was found in the bifenthrin-resistant individuals. When compared with the susceptible strain (Rp-SS), the Rp-BIF strain was significantly inferior in multiple life table parameters, exhibiting a relative fitness of 0.69. Our toxicological and biochemical studies indicated that multiple mechanisms of resistance might be involved in the resistance trait. Our results provide insight into the bifenthrin resistance of R. padi and can contribute to improve management of bifenthrin-resistant R. padi in the field. [ABSTRACT FROM AUTHOR]

Essential oils (EOs), including those from the Asteraceae plants, have been shown to have promising insecticidal activity against a wide range of insect pests. Understanding the mechanism of action of EOs is one of the studied aspects. The present study aimed to evaluate the effect of essential oils from Achillea millefolium, Santolina chamaecyparissus, Tagetes patula and Tanacetum vulgare on the settling and probing behavior of the bird cherry-oat aphid (Rhopalosiphum padi L.). In addition, the effect of the oils on the activity of such enzymes as trypsin, pepsin and α- and β-glucosidase involved in the metabolism of proteins and sugars of the insects was examined. The leaf-choice bioassays demonstrated that the studied EOs limited aphid settling for at least 24 h after the treatment. The application of EOs also inferred with aphid probing behavior by reducing the total probing time and total duration of phloem sap ingestion. Aphids spent more time in the search phase due to an increase in the number and total duration of pathway phases. Moreover, the activity of the studied proteases and glucosidases significantly decreased in R. padi females exposed to the EOs. The enzyme inhibition varied depending on the applied oil and exposure time. Generally, the EOs with stronger deterrent activity also showed higher inhibitory effects. The results suggest that the tested EOs disrupt key digestive processes in R. padi which may be an important factor determining their aphicidal activity.

The bird cherry‐oat aphid Rhopalosiphum padi (L.) (Hemiptera: Aphididae) is a key pest of wheat in China. Chitosan oligosaccharide (COS) has been widely used due to its biocompatibility, antibacterial activity, environmental friendliness and convenient extraction. This study was aimed at determining the acute toxicity of COS on R. padi and transgenerational effects of sublethal concentrations of COS on the biological characteristics of R. padi. The results indicated that COS possessed acute toxicity against R. padi after 48 h of exposure (LC50: 1227.35 mg/L). The sublethal concentration of COS (LC15: 260 mg/L) induced a decrease in adult longevity, adult prereproductive period and fecundity in the first filial generation (F1). Moreover, in F1 progeny, nymphal (1st–3rd), preadult and total prereproductive period significantly enhanced due to sublethal dose. Moreover, finite rate of increase (λ), the intrinsic rate of increase (r) and net reproductive rate (R0) of F1 progeny were significantly decreased, whereas a sublethal COS concentration exposure significantly increased the mean generation time (T) of F1 progeny. Overall, the study shows that sublethal concentration of COS can significantly suppress population growth of R. padi F1 generation, showing the potential of COS as a biorational option to manage aphids. [ABSTRACT FROM AUTHOR]

[Objectives] To investigate the effects of different levels of fertilizer reduction on the occurrence of three species of wheat aphids (Schizaphis graminum, Sitobion miscanthi and Rhopalosiphum padi) and two species of wheat mites (Penthaleus major and Petrobia latens), and on wheat yield, in wheat fields in Shandong. [Methods] The population dynamics of wheat aphids and mites, which are the main crop pests in wheat fields, were studied under standard (600 kg/hm2), 10% reduced (540 kg/hm2), 20% reduced (480 kg/hm2), 37.5% reduced (375 kg/hm2) and 50% reduced (300 kg/hm2), applications of fertilizer. Yield indices (including biomass per ear, ears per meter of wheat row, seed weight per 10 ears, weight of 1 000 seeds and yield per 667 m2) under the above fertilizer levels were also investigated. [Results] The occurrence of wheat aphids and mites were reduced to different degrees by the different levels of fertilizer application. The occurrence of S. graminum and S. miscanthi were strongly, and negatively, correlated with the level of fertilizer reduction. However, the level of fertilizer application had no significant effect on the seed weight per 10 ears or per 1 000 seeds. Reducing the amount of fertilizer by 50% significantly decreased the biomass per ear, ears per meter of wheat row and yield per 667 m2. However, a regression model indicates that wheat yield is not affected when the amount of fertilizer is reduced by < 23.16%. [Conclusion] Moderate reduction in the amount of fertilizer applied to wheat fields reduces the abundance of the main wheat pests without greatly affecting wheat yield. [ABSTRACT FROM AUTHOR]

The need for alternatives to synthetic pesticides is a priority today, especially when these pesticides are directed against aphids, one of the more challenging pests facing modern agriculture. Essential oils may be one of these alternatives. We assayed the insecticidal potential of essential oils from Thymus vulgaris, Rosmarinus officinalis var. 'prostratus' and Lavandula dentata. Essential oil extraction was carried out by hydrodistillation in a Clevenger-type apparatus for 3 h and their respective composition was elucidated by gas chromatography-mass spectrometry. The essential oil fraction from T. vulgaris contained 81.20% monoterpenoids and 12.85% sesquiterpenoids; R. officinalis var. 'prostratus' contained 91.98% monoterpenoids and 1.93% sesquiterpenoids, while L. dentata contained 69.60% monoterpenoids and 8.05% sesquiterpenoids. The major components found were 1,8-cineole (18.11%), camphor (11.18) and borneol (10.32%) in T. vulgaris; α-pinene (18.72%), verbenone (13.42%) and 1,8-cineole (10.32%) in R. officinalis; and 1,8-cineole (34.65%), camphor (7.58%) and β-pinene (6.39%) in L. dentata. The insecticidal activity of the essential oils was evaluated by contact toxicity bioassays against the bird cherry oat aphid, Rhopalosiphum padi L. We observed a mortality rate of 78.3% ± 23.9 at 15 μL/mL with T. vulgaris, 54.7% ± 25.8 with L. dentata (although at a lower concentration, 10 μL/mL), and 56.7% ± 25.6 at 15 μL/mL with R. officinalis. Our results suggest that thyme essential oil may be particularly promising for integrated aphid management provided that specific conditions of use and dosages are observed. [ABSTRACT FROM AUTHOR]

The deciphering of the epidemiology of a plant virus has long been focused on the study of interactions between partners of one pathosystem. However, plants are exposed to numerous viruses which lead to frequent co-infection scenarios. This can change characteristics of virus-vector-host interactions and could impact the epidemiology of viral diseases. Barley yellow dwarf virus-PAV (BYDV-PAV; species: Luteovirus pavhordei; genus Luteovirus), wheat dwarf virus (WDV; genus Mastrevirus) and their respective vectors (BYDV-PAV: e.g. Rhopalosiphum padi and WDV: Psammotettix alienus) are commonly found in cereal fields. Wheat plants co-infected with BYDV-PAV and WDV have been reported from field surveys, although epidemiological outcomes of BYDV-PAV - WDV interactions in planta have not yet been studied. Experiments were carried out to evaluate and compare, through different competition scenarios (i.e. single- and co-(simultaneous and sequential) inoculations), the efficiency of BYDV-PAV and WDV to infect, to accumulate in and to be spread between wheat plants. Moreover, the impact of competition scenarios on the biological parameters of these two viruses was evaluated at different stages of the infection and with plants at different ages at inoculation. Results showed i) that these viruses achieve their infection cycle and their plant-to-plant transmission with different efficiencies and ii) BYDV-PAV - WDV interactions lead to different phenotypes ranging from antagonism to synergism. Finally, when these two viruses share a host, the nature and strength of virus-virus interactions varied depending on the order of virus arrival, stages of the infection cycle and plant age at inoculation. Precisely, the introduction (i.e. co-and sequential inoculation) and infection process (i.e. virus accumulation) of BYDV-PAV in a wheat benefit from the presence of WDV. For the latter, the sympatry with BYDV-PAV exerts opposite pressure on parameters involved in virus introduction (i.e. benefit during sequential inoculation) and spread (i.e. lower transmission efficiency and virus accumulation in co-infected plants). In the context of increased potential exposure of crops to insect vectors, this study participates in a better understanding of the impact of BYDV-PAV and WDV co-infections on biological and ecological parameters of the diseases induced by these viruses. [ABSTRACT FROM AUTHOR]

The objective of this paper is to document the occurrence of pests recorded in a large-scale pilot field experiment, where a unique set of newly-introduced herbaceous energy crops was tested under conditions of eastern Slovakia. The set consisted of Elymus elongatus, Secale cereanum, Silphium perfoliatum, Galega orientalis, Sida hermaphrodita, Panicum virgatum, Amaranthus spp., Panicum miliaceum, Sorghum sudanense, and Sorghum bicolor. A total of 14 cultivars were tested on 4 sites during 4 crop years (2016 – 2020). At least 17 species of pests were recorded in total, as some of the species may represent the identity of the couple or several relative ones, which was rare only as usually a fower common species. The occurred pests list consists of Anisoplia lata Erichson, Agriotes lineatus L., Capreolus capreolus L., Deroceras agreste L., Oulema gallaeciana Heyden, Lepisma saccharinum L., Lepus europaeus Pallas, Meloe proscarabaeus L., Metcalfa pruinosa Say, Microtus arvalis Pallas, Philaenus spumarius L., Psylliodes chrysocephala L., Rhopalosiphum padi L., stemborers as any insect larva or arthropod boring into plant stem, Sus scrofa L., Aleyrodes proletella L., Tettigonia viridissima L., and Trialeurodes vaporariorum Westwood. Overall, the occurrence of pests was regular and scattered, and damages caused by them were negligible usually, but a total destruction of the crop stand even cultivar-specific was recorded too. Most of the meaningful pests are primarily field hunting animals and only secondarily commonly occurring insect species, which for further observations are desirable in order to capture the tendency of important pests' overpopulation, confirming respectively. Although even rare finding of the single caterpillar of Xylena exsoleta exsoleta L. was recorded in a buffer zone, within the experiment no newly introduced pest species was recorded. [ABSTRACT FROM AUTHOR]

The objective of this study was to observe the response of the bird cherry oat aphid, Rhopalosiphum padi (Linnaeus, 1758) to field rate equivalents of insecticides, by using bioassays of vials coated with the pyrethroid, λ-cyhalothrin. The results from the geographically separated Irish R. padi colonies indicated a susceptible response, which was a similar finding to the UK which showed sensitivity in this species of cereal aphids. Monitoring the susceptibility status of aphids using bioassays gives information regarding developments of any tolerance, which could be a precursor, or resistance against the target chemical insecticide, which is an important integrated pest management tool.

Novel nereistoxin derivatives containing phosphonate were synthesized and characterized via 31P, 1H and 13C NMR and HRMS. The anticholinesterase activity of the synthesized compounds was evaluated on human acetylcholinesterase (AChE) using the in vitro Ellman method. Most of the compounds exhibited good inhibition of acetylcholinesterase. All of these compounds were selected to assess their insecticidal activity (in vivo) against Mythimna separata Walker, Myzus persicae Sulzer and Rhopalosiphum padi. Most of the tested compounds displayed potent insecticidal activity against these three species. Compound 7f displayed good activity against all three insect species, showing LC50 values of 136.86 μg/mL for M. separata, 138.37 μg/mL for M. persicae and 131.64 μg/mL for R. padi. Compound 7b had the highest activity against M. persicae and R. padi, with LC50 values of 42.93 μg/mL and 58.19 μg/mL, respectively. Docking studies were performed to speculate the possible binding sites of the compounds and explain the reasons for the activity of the compounds. The results showed that the compounds had lower binding energies with AChE than with the acetylcholine receptor (AchR), suggesting that compounds are more easily bound with AChE. [ABSTRACT FROM AUTHOR]

Recent studies have demonstrated that cultivar mixtures can reduce aphid plant acceptance and population development. It is still unknown as to which underlying mechanisms may contribute to this phenomenon. We investigated the effects of volatile interactions between undamaged barley cultivars on aphid feeding behavior and performance in the laboratory. Spring barley (Hordeum vulgare L.) cultivar Salome was exposed to volatiles from Fairytale (SeF), Anakin (SeA), or clean air (Se0). We used an electrical penetration graph to test the effect of exposure to neighbor volatiles on the feeding behavior and performance of bird cherry-oat aphids (Rhopalosiphum padi L.). We also assessed aphid relative growth rate, intrinsic rate of increase, and development time on exposed and unexposed Salome plants. Aphids spent significantly longer time on epidermis and mesophyll plant tissues on SeF than Se0, and no difference was observed between SeA and Se0. Significant decreases in the duration of phloem ingestion and phloem sustained ingestion were recorded in SeF showing that volatile-induced effects cause difficulty for aphids to feed. However, no differences in these variables were detected between SeA and Se0. We also observed reduced aphid relative growth rate and intrinsic rate of increase on SeF compared to Se0 and SeA. Our study demonstrated that, in a specific combination, exposure of one barley cultivar to volatiles from another one can change aphid feeding behavior and performance, probably due to changes in host plant properties/quality. Our results provide an insightful explanation of mechanisms responsible for the reduced aphid population development previously observed in the field. [ABSTRACT FROM AUTHOR]