Smartphone-integrated paper-based sensing platform for the visualization and quantitative detection of pymetrozine

Pymetrozine (PYM) is an effective pyridine insecticide for controlling aphids, while its residues pose a serious threat to human health. Herein, a europium complex (Eu-DBPA, DBPA represents deprotonated 2,5-dibromoterephthalic acid ligand) probe was prepared for the detection of PYM via fluorescence quenching. The detection process has the advantages of short response time (2 min), wide linear range (0-4 and 4-45 mg/kg) and low detection limit (2.2 μg/kg). Furthermore, a portable detection platform was designed by integrating Eu-DBPA-based paper strip with smartphone and applied for the visual detection of PYM in real cucumber, tomato, cabbage and apple samples, obtaining satisfactory recovery (99.00 %-107.00 %) and low standard deviation (RSD < 3.4 %). In addition, a logic gate device was designed to simplify the detection process. The smartphone-integrated paper-based probe detection platform provides a new strategy for intelligent and online identification of hazards in environmental and biological samples.

Aphid Cerosipha forbesi control using Piper macedoi Yunck essential oil in strawberry crop

Strawberry is a food rich in bioactive compounds with great antioxidant potential. However, due to the high incidence of pests that affect crop cultivation, phytosanitary management still lacks control methods for agroecological cultivation. Thus, the present research aimed to evaluate the chemical composition and the potential of the essential oil of the leaves of Piper macedoi in the control of Cerosipha forbesi in laboratory and semi-field conditions. The concentration of essential oil in the leaves of P. macedoi that showed the highest mortality was 2.0 ml/L of oil, with a mortality above 91% under laboratory conditions. A mortality rate of 80% for all concentrations tested was observed after 24 h in all conditions tested. Thus, using essential oil from the leaf of P. macedoi can be a highly viable strategy in managing the aphid C. forbesi since it showed high mortality rates with small doses of oil.

Communication between undamaged plants can elicit changes in volatile emissions from neighbouring plants, thereby altering their susceptibility to aphids

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.

Pyrethroid and carbamate resistance in Czech populations of Myzus persicae (Sulzer) from oilseed rape

BACKGROUND

Failures in controlling Myzus persicae by pyrethroids and carbamates have been observed in Czechia since 2018. Eleven populations collected from Czech oilseed rape fields during 2018-2021 were tested for susceptibility to 11 insecticides. The presence of a single nucleotide polymorphism (SNP) leading to knockdown resistance in M. persicae populations was screened using allelic discriminating quantitative real-time polymerase chain reaction (qPCR). The presence of mutations related with the resistance of M. persicae to pyrethroids and carbamates was detected by sequencing paratype voltage-gated sodium channel and acetylcholinesterase 2 genes, respectively.

RESULTS

Resistance to alpha-cypermethrin and pirimicarb was detected in most of the tested populations. The L1014F mutation was detected in 44.5% of M. persicae individuals surviving the field-recommended dose of alpha-cypermethrin. Sequencing of partial para gene for paratype voltage-gated sodium channel detected five different SNPs leading to four amino acid substitutions (kdr L1014F; s-kdr M918L; s-kdr M918T; and L932F). No pyrethroid-sensitive genotype was detected. The S431F amino acid substitution conferring resistance to carbamates was detected in 11 of 20 individuals with different pyrethroid-resistance genotypes.

CONCLUSION

Resistance of M. persicae to both pyrethroids and carbamates was detected in nine of 11 populations. High resistance of M. persicae was correlated with mutations of the sodium channel. Sulfoxaflor, flonicamid, and spirotetramat are proposed as effective compounds to control pyrethroid- and carbamate-resistant populations of M. persicae. © 2023 Society of Chemical Industry.

Understanding the onion aphid Neotoxoptera formosana's (Hemiptera: Aphididae) interaction with Allium (Asparagales: Amaryllidaceae) crops: a comprehensive study of feeding patterns and life history traits

The onion aphid, Neotoxoptera formosana, poses a significant threat to Allium crops worldwide, causing considerable economic losses and quality degradation. To develop effective pest management strategies, it is crucial to understand the feeding behavior and life history of this pest on different Allium crops. In this study, the electrical penetration graph (EPG) technique was used to monitor the thorn-feeding behavior of the onion aphid on 4 Allium crops: leek, chive, garlic, and shallot. The EPG data revealed distinct feeding patterns, with garlic and shallots being more preferred hosts than chives. Additionally, the aphids primarily fed on the phloem in garlic and shallots. Analysis of life history trait showed that chives provided the most favorable conditions for aphid development and reproduction, while leek exhibited relatively unfavorable conditions. Examination of leaf histology also revealed differences among the crops, which may influence aphid feeding behavior. This study provides valuable insights into the interaction between the onion aphid and different Allium crops, aiding in the development of comprehensive pest control strategies to minimize crop damage and economic losses. The use of advanced techniques like EPG contributes to a more detailed understanding of aphid behavior and shows promise for improving pest management in other plant-pest interactions.

The Effect of Essential Oils from Asteraceae Plants on Behavior and Selected Physiological Parameters of the Bird Cherry-Oat Aphid

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.

How generalist insect herbivores respond to alien plants? The case of Aphis fabae-Myzus persicae-Rhododendron ponticum

BACKGROUND

The enemy release hypothesis (ERH) predicts that alien plant species are unsuitable hosts for native phytophagous insects. However, the biotic resistance hypothesis (BRH) predicts that generalist herbivores may prefer an alien plant over their common host plant. In this study, we have tested these two hypotheses by comparing the potential colonization of the invasive Pontic rhododendron (Rhododendron ponticum L.) versus the common rearing host plants by two generalist aphid species (Aphis fabae and Myzus persicae). We assessed (i) the probing behavior using the electrical penetration graph (EPG) technique and (ii) survival and fecundity in Petri dishes.

RESULTS

The results showed the inability of A. fabae and Myzus persicae to immediately colonize R. ponticum. Despite their ability to feed on this invasive plant, the two aphid species hardly survived and poorly reproduced.

CONCLUSION

Our results are consistent with the ERH, since R. ponticum appeared as an unsuitable host for native phytophagous insects. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Systemic resistance induced in tomato plants by Beauveria bassiana-derived proteins against tomato yellow leaf curl virus and aphid Myzus persicae

BACKGROUND

Tomato (Solanum lycopersicum L.) is an economically important vegetable crop around the globe. Tomato yellow leaf curling (TYLC) is the most devastating viral disease posing a serious threat to tomato production throughout the tropical and subtropical world. Induction of microbe-mediated systemic resistance in plants has been of great interest in recent years as a novel microbiological tool in disease and insect pest management. This in-vitro study aimed to determine the effectiveness of different strains (BB252, BB72 and ARSEF-2860) of a hypocreal fungus Beauveria bassiana against TYLCV disease and aphid Myzus persicae. Potted tomato plants exogenously treated with conidial and filtrate suspensions of B. bassiana strains and of their partially purified or purified proteins were exposed to TYLCV inoculum and aphid M. persicae.

RESULTS

Results showed a significant suppression of TYLCV disease severity index by the exogenous application of conidial, filtrate and protein treatments of all B. bassiana strains and this response was directly proportional to the treatment concentration. Similarly, mean fecundity rate of M. persicae was also significantly reduced by the highest concentration of ARSEF-2860-derived elicitor protein PeBb1, followed by the highest concentrations of BB252- and BB72-derived partially purified proteins. Moreover, these B. bassiana-derived proteins also caused a significant upregulation of most of the plant immune marker genes associated with plant defense.

CONCLUSION

Overall, the study findings suggest that these B. bassiana strains and their partially purified or purified elicitor proteins could be effective biological tools for the management of TYLCV and aphid infestation on tomato plants. © 2023 Society of Chemical Industry.

Synthesis and Insecticidal Evaluation of 3,5-Dicyanopyridines Against Cotton Aphids via Microwave-Assisted Multicomponent Reactions

Certain 2-amino-6-alkoxy-4-arylpyridine-3,5-dicyanide 1a-e were prepared via a straightforward process using microwave technology rather than conventional methods. This involved reaction of arylidenemalononitrile thru propanedinitrile in the occurrence of sodium alkoxide under MW. While, their positional isomer 4-amino-6-alkoxy-2-arylpyridine-3,5-dicyanide 3a-j have been separated from the reaction of aryl aldehydes with 2-aminoprop-1-ene-1,1,3-tricarbonitrile 2 in the presence of sodium alkoxide using microwave technic. Furthermore, the insecticidal properties of all synthesized compounds were observed with respect to Cotton aphid nymphs and adults. Neonicotinoid pesticides are indicated as the most effective pesticides toward aphids and many other pests. Many insecticides are discovered as novelties. As a result, several pyridine compounds were chemical method synthesized to serve as equivalents of neonicotinoids, a broad class of insecticides. With LC50 value of 0.03 mg/L, components 3g exhibit the highest insecticidal bioactivity. This work discusses how to find new chemicals that could be used as insecticidal agents in the future.

Methyl-salicylate (MeSA)-mediated airborne defence

Stressed plants emit a variety of chemicals into the environment, leading to increased pest resistance in neighbouring plants but the genetic and molecular mechanisms of the emissions remain obscure. Recently, Gong et al. identified novel methyl salicylate (MeSA)-mediated airborne defence that confers resistance to neighbouring plants against aphids and viruses.

Larval development and voracity of Eupeodes americanus (Diptera: Syrphidae): comparison of the focal prey Aphis gossypii (Hemiptera: Aphididae) and the banker prey Rhopalosiphum padi (Hemiptera: Aphididae)

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.

Hormetic effects of thiamethoxam on Schizaphis graminum: demographics and feeding behavior

In agroecosystems, insects contend with chemical insecticides often encountered at sublethal concentrations. Insects' exposure to these mild stresses may induce hormetic effects, which has consequences for managing insect pests. In this study, we used an electrical penetration graph (EPG) technique to investigate the feeding behavior and an age-stage, two-sex life table approach to estimate the sublethal effects of thiamethoxam on greenbug, Schizaphis graminum. The LC5 and LC10 of thiamethoxam significantly decreased longevity and fecundity of directly exposed adult aphids (F0). However, the adult longevity, fecundity, and reproductive days (RPd)-indicating the number of days in which the females produce offspring - in the progeny generation (F1) exhibited significant increase when parental aphids (F0) were treated with LC5 of the active ingredient. Subsequently, key demographic parameters such as intrinsic rate of increase (r) and net reproductive rate (R0) significantly increased at LC5 treatment. EPG recordings showed that total durations of non-probing (Np), intercellular stylet pathway (C), and salivary secretion into the sieve element (E1) were significantly increased, while mean duration of probing (Pr) and total duration of phloem sap ingestion and concurrent salivation (E2) were decreased in F0 adults exposed to LC5 and LC10. Interestingly, in the F1 generation, total duration of Np was significantly decreased while total duration of E2 was increased in LC5 treatment. Taken together, our results showed that an LC5 of thiamethoxam induces intergenerational hormetic effects on the demographic parameters and feeding behavior of F1 individuals of S. graminum. These findings have important implications on chemical control against S. graminum and highlight the need for a deeper understanding of the ecological consequences of such exposures within pest management strategies across the agricultural landscapes.

GNViT- An enhanced image-based groundnut pest classification using Vision Transformer (ViT) model

Crop losses caused by diseases and pests present substantial challenges to global agriculture, with groundnut crops particularly vulnerable to their detrimental effects. This study introduces the Groundnut Vision Transformer (GNViT) model, a novel approach that harnesses a pre-trained Vision Transformer (ViT) on the ImageNet dataset. The primary goal is to detect and classify various pests affecting groundnut crops. Rigorous training and evaluation were conducted using a comprehensive dataset from IP102, encompassing pests such as Thrips, Aphids, Armyworms, and Wireworms. The GNViT model's effectiveness was assessed using reliability metrics, including the F1-score, recall, and overall accuracy. Data augmentation with GNViT resulted in a significant increase in training accuracy, achieving 99.52%. Comparative analysis highlighted the GNViT model's superior performance, particularly in accuracy, compared to state-of-the-art methodologies. These findings underscore the potential of deep learning models, such as GNViT, in providing reliable pest classification solutions for groundnut crops. The deployment of advanced technological solutions brings us closer to the overarching goal of reducing crop losses and enhancing global food security for the growing population.

Potential of Thuja occidentalis L. Essential Oil and Water Extracts against Field Crop Pests

Thuja occidentalis L. essential oil (EOTO) and its compounds, such as terpinyl acetate, bornyl acetate, and β-thujone, are claimed to be highly effective against some storage pests, sanitary insects, or pests of fruit trees, while data about its use in protecting field crops are very scarce. There is also a lack of information in the literature about the insecticidal value of water extracts from T. occidentalis (WETOs). Both essential oils (EOs) and water extracts (WEs) from various plants have advantages and disadvantages in terms of their use as insecticides. EOs are generally more effective, but their preparation is more complicated and quite expensive. In turn, WEs are simple to prepare and cheap, but they often have limited effectiveness. Moreover, significant differences in responses exist depending on the species of the donor plant, the method of preparing the extract, its concentration, the species of the pest being controlled, the developmental stage, and even the gender of the pest. The goals of the research were to assess the effect of EOTO and WETOs prepared from dry and fresh matter on the mortality, feeding, and body mass changes of important crop pests, i.e., the black bean aphid, pea leaf weevil, and Colorado potato beetle (CPB), respectively, as well as on the mortality and voracity of non-target organism Asian lady beetle young larvae. EOTO showed significant aphicidal activity with LC50 = 0.8267% and 0.2453% after 42 h of the experiment for nymphs and wingless females of black bean aphid, respectively. Adults of CPB were more resistant to EOTO than aphids, with LC50 values for females equal to 1.5327% and 1.3113% after 48 h and after 72 h of the experiment. There was no significant effect of EOTO on CPB foraging. Calculated LC50 values for pea leaf weevil adults were lower than those for CPB (0.9638% and 0.8573% for males after 12 h and 24 h, respectively). In the case of this pest, a clear reduction in foraging was obtained, with higher concentrations of EOTO resulting in more pronounced reductions in foraging behavior. Concentrations of EOTO above 0.5%, which showed efficacy against the aphid, were lethal to 3-day-old larvae of the Asian lady beetle. WETOs, in turn, showed significant potential in inhibiting adult pea leaf weevil feeding, with very low or no effectiveness in reducing A. fabae and CPB, respectively.

Dispersal stabilizes coupled ecological and evolutionary dynamics in a host-parasitoid system

When ecological and evolutionary dynamics occur on comparable timescales, persistence of the ensuing eco-evolutionary dynamics requires both ecological and evolutionary stability. This unites key questions in ecology and evolution: How do species coexist, and what maintains genetic variation in a population? In this work, we investigated a host-parasitoid system in which pea aphid hosts rapidly evolve resistance to Aphidius ervi parasitoids. Field data and mathematical simulations showed that heterogeneity in parasitoid dispersal can generate variation in parasitism-mediated selection on hosts through time and space. Experiments showed how evolutionary trade-offs plus moderate host dispersal across this selection mosaic cause host-parasitoid coexistence and maintenance of genetic variation in host resistance. Our results show how dispersal can stabilize both the ecological and evolutionary components of eco-evolutionary dynamics.

Discovery of New Botanical Insecticides: Identification and Insecticidal Activity of Saponins from Clematis obscura Maxim and Insights into the Stress Response of Acyrthosiphon pisum Harris

To discover new botanical products-based insecticide candidates, 14 triterpenoid saponins (1-14) including four new ones, obscurosides A-D (1-4), were isolated from Clematis obscura Maxim as potential agrochemicals against Acyrthosiphon pisum Harris and Plutella xylostella (L.). Compounds 1-3 were characterized by a rare ribose substitution at C-3, and 4 was a bidesmoside glycosylated at the rare C-23 and C-28 positions of the oleanane aglycone. Compounds 10 (median antifeeding concentration, AFC50 = 1.10 mg/mL; half-lethal concentration, LC50 = 1.21 mg/mL) and 13 (AFC50 = 1.09 mg/mL, LC50 = 1.37 mg/mL) showed significant insecticidal activities against third larvae of P. xylostella at 72 h. All saponins displayed antifeedant activities against A. pisum with the deterrence index of 0.20-1.00 at 400 μg/mL. Compound 8 showed optimal oral toxicity (LC50 = 50.09 μg/mL) against A. pisum, followed by compounds 1, 5-7, 9, and 14 (LC50 = 90.21-179.25 μg/mL) at 72 h. The shrinkage of the cuticle and the destruction of intestinal structures of microvilli, nucleus, endoplasmic reticulum, and mitochondria were toxic symptoms of 8-treated A. pisum. The significantly declined Chitinase activity in 8-treated A. pisum with an inhibition rate of 79.1% at LC70 (70% lethal concentration) could be the main reason for its significant oral toxicities. Molecular docking revealed favorable affinities of compounds 1 and 8 with group I Chitinase OfChtI (Group I Chitinase from Ostrinia furnacalis) through conventional hydrogen bonds and alkey/π-alkey interactions by different patterns. These results will provide valuable information for the development of novel botanical pesticides for the management of insect pests, especially against A. pisum.

Evaluation of aphid resistance on different rose cultivars and transcriptome analysis in response to aphid infestation

BACKGROUND

The rose is one of the most important ornamental flowers in the world for its aesthetic beauty but can be attacked by many pests such as aphids. Aphid infestation causes tremendous damage on plant tissues leading to harmed petals and leaves. Rose cultivars express different levels of resistance to aphid infestation yet the information remains unclear. Not only that, studies about the transcriptional analysis on defending mechanisms against aphids in rose are limited so far.

RESULTS

In this study, the aphid resistance of 20 rose cultivars was evaluated, and they could be sorted into six levels based on the number ratio of aphids. And then, a transcriptome analysis was conducted after aphid infestation in one high resistance (R, Harmonie) and one highly susceptibility (S, Carefree Wonder) rose cultivar. In open environment the majority of rose cultivars had the highest aphid number at May 6th or May 15th in 2020 and the resistance to infestation could be classified into six levels. Differential expression analysis revealed that there were 1,626 upregulated and 767 downregulated genes in the R cultivar and 481 upregulated and 63 downregulated genes in the S cultivar after aphid infestation. Pathway enrichment analysis of the differentially expressed genes revealed that upregulated genes in R and S cultivars were both enriched in defense response, biosynthesis of secondary metabolites (phenylpropanoid, alkaloid, and flavonoid), carbohydrate metabolism (galactose, starch, and sucrose metabolism) and lipid processing (alpha-linolenic acid and linolenic acid metabolism) pathways. In the jasmonic acid metabolic pathway, linoleate 13S-lipoxygenase was specifically upregulated in the R cultivar, while genes encoding other crucial enzymes, allene oxide synthase, allene oxide cyclase, and 12-oxophytodienoate reductase were upregulated in both cultivars. Transcription factor analysis and transcription factor binding search showed that WRKY transcription factors play a pivotal role during aphid infestation in the R cultivar.

CONCLUSIONS

Our study indicated the potential roles of jasmonic acid metabolism and WRKY transcription factors during aphid resistance in rose, providing clues for future research.

Intercropped Flemingia macrophylla successfully traps tea aphid (Toxoptera aurantia) and alters associated networks to enhance tea quality

BACKGROUND

The tea aphid, Toxoptera aurantia is a destructive pest causing severe damage to the quality and yield of tea, Camellia sinensis. Relying on chemical insecticides to control this pest causes adverse ecological and economic consequences. Trap plants are an eco-friendly alternative strategy to mitigate pest damage on focal plants by attracting target insects and natural enemies. Yet, the utilization of trap plants in tea plantations remains limited. Besides, the effects of the trap plant on the tea aphid-ant-predator community and tea quality and yield are unknown.

RESULTS

Intercropped Flemingia macrophylla successfully trapped tea aphids and enhanced the complexity of aphid-ant-predator networks over three consecutive years compared to monoculture management. Moreover, F. macrophylla significantly increased the abundance of natural predators by 3100% and species richness by 57%. The increasing predators suppressed the aphid population and hampered its spillover to neighbouring tea plants. Consequently, F. macrophylla improved tea quality by an 8% increase in soluble sugar and a 26% reduction in polyphenols to amino acids ratio.

CONCLUSION

The study illustrated that F. macrophylla is a suitable trap crop for tea aphid control in tea plantations. This legume increases species nodes and strengthens multiple connections in aphid-associated communities through its cascade effects, improving tea quality. These findings shed light on the potential application of trap plants in tea plantations as an efficient integrated pest management (IPM) strategy. © 2023 Society of Chemical Industry.

Aphids increase their rate of survival on emergent aquatic plants through niche construction

Flooding or rain is a threat to many insects in nature, including herbivorous invertebrates whose hosts are emergent aquatic plants. They may thus have developed particular adaptations to withstand the flooding that is a feature of emergent plants' environment. The aphid Hyalopterus pruni (Hemiptera: Aphididae) modifies the physical and chemical conditions of its habitat by periodically spreading wax around itself with its hind legs. This behaviour constitutes a form of niche construction. We hypothesized that the aphid decreases its risk of death of own or around other individuals when submerged in water by spreading wax powder secreted from its body onto the leaves of its host plant, Phragmites australis. We compared the hydrophobicity of waxed and normal leaf surfaces. Next, we compared the survival rates of wax-powdering and nonwax-powdering aphids under submerged and rainy conditions in the laboratory and in the field. Finally, we examined whether the aphids' wax-powdering behaviour increased as a result of experiencing brief submergence or rain. The surface of the waxed area was significantly more water-repellent than the surface of unwaxed leaves. The waxed areas held air bubbles when under water. In experiments, aphids without wax around themselves exhibited lower survival rates: 22.9% in laboratory conditions and 15.7% in field conditions after 48 hr underwater. In contrast, aphids that secreted wax had higher survival rates, with 41.5% and 38.2% under laboratory and field conditions, respectively, after the same duration. Aphids exposed to rainfall showed similar results. Moreover, aphids that had experienced rain or submersion for 24 hr engaged in increased wax-powdering behaviour. These results indicate that aphids reduce their risk of drowning by powdering secreted wax onto the surface of leaves around them. Our findings suggest that niche construction by herbivorous invertebrates supports their ability to utilize host plants that grow under stressful conditions, such as emergent plants that are subject to periodic inundation.

QM/MM study of the catalytic reaction of aphid myrosinase

Brevicoryne brassicae, an aphid species, exclusively consumes plants from the Brassicaceae family and employs a sophisticated defense mechanism involving a myrosinase enzyme that breaks down glucosinolates obtained from its host plants. In this work, we employed combined quantum mechanical and molecular mechanical (QM/MM) calculations and molecular dynamics (MD) simulations to study the catalytic reaction of aphid myrosinase. A proper QM region to study the myrosinase reaction should contain the whole substrate, models of Gln-19, His-122, Asp-124, Asn-166, Glu-167, Lys-173, Tyr-180, Val-228, Tyr-309, Tyr-346, Ile-347, Glu-374, Glu-423, Trp-424, and a water molecule. The calculations show that Asp-124 and Glu-423 must be charged, His-122 must be protonated on NE2, and Glu-167 must be protonated on OE2. Our model reproduces the anomeric retaining characteristic of myrosinase and indicates that the deglycosylation reaction is the rate-determining step of the reaction. Based on the calculations, we propose a reaction mechanism for aphid myrosinase-mediated hydrolysis of glucosinolates with an overall barrier of 15.2 kcal/mol. According to the results, removing a proton from Arg-312 or altering it to valine or methionine increases glycosylation barriers but decreases the deglycosylation barrier.

Rational design, synthesis and binding mechanisms of novel benzyl geranate derivatives as potential eco-friendly aphid repellents

BACKGROUND

The push-pull strategy is considered as a promising eco-friendly method for pest management. Plant volatile organic compounds (PVOCs) act as semiochemicals constitute the key factor in implementing this strategy. Benzyl alcohol and geraniol, as functional PVOCs, were reported to regulate insect behavior, showing the potential application in pest control. Using geraniol as lead, a geraniol derivative 5i with fine repellent activity was discovered in our previous work. In order to explore novel, eco-friendly aphid control agents, a series of benzyl geranate derivatives was designed and synthesized using 5i as the lead and benzyl alcohol as the active fragment.

RESULTS

Benzyl alcohol was firstly evaluated to have repellent activity to Acyrthosiphon pisum. Based on this repellent fragment, a series of novel benzyl geranate derivatives was rationally designed and synthesized using a scaffold-hopping strategy. Among them, compound T9, with a binding affinity (Kd  = 0.43 μm) and a substantial repellency of 64.7% against A. pisum, is the most promising compound. Molecule docking showed that hydrophobic and hydrogen-bonding interactions substantially influenced the binding affinity of compounds with ApisOBP9. Additionally, T9 exhibited low-toxicity to honeybees and ladybugs.

CONCLUSION

Using a simple scaffold-hopping strategy combined with active fragment benzyl alcohol, a new derivative T9, with high aphid-repellency and low-toxicity to nontarget organisms, can be considered as a novel potential eco-friendly aphid control agent for sustainable agriculture. © 2023 Society of Chemical Industry.

Computational Prediction of Structure, Function, and Interaction of Myzus persicae (Green Peach Aphid) Salivary Effector Proteins

Similar to plant pathogens, phloem-feeding insects such as aphids deliver effector proteins inside their hosts that act to promote host susceptibility and enable feeding and infestation. Despite exciting progress toward identifying and characterizing effector proteins from these insects, their functions remain largely unknown. The recent groundbreaking development in protein structure prediction algorithms, combined with the availability of proteomics and transcriptomic datasets for agriculturally important pests, provides new opportunities to explore the structural and functional diversity of effector repertoires. In this study, we sought to gain insight into the infection strategy used by the Myzus persicae (green peach aphid) by predicting and analyzing the structures of a set of 71 effector candidate proteins. We used two protein structure prediction methods, AlphaFold and OmegaFold, that produced mutually consistent results. We observed a wide continuous spectrum of structures among the effector candidates, from disordered proteins to globular enzymes. We made use of the structural information and state-of-the-art computational methods to predict M. persicae effector protein properties, including function and interaction with host plant proteins. Overall, our investigation provides novel insights into prediction of structure, function, and interaction of M. persicae effector proteins and will guide the necessary experimental characterization to address new hypotheses. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Discovery of insecticide resistance in field-collected populations of the aphid pest, Acyrthosiphon kondoi Shinji

BACKGROUND

The bluegreen aphid (Acyrthosiphon kondoi) is a worldwide pest of alfalfa, pulses, and other legume crops. An overreliance on insecticides to control A. kondoi has potentially placed populations under selection pressure favouring resistant phenotypes, but to date, there have been no documented cases of insecticide resistance. Recently, Australian growers began reporting that conventional insecticides were failing to adequately control A. kondoi populations, prompting this laboratory-based investigation into whether these populations have evolved resistance.

RESULTS

We discovered four A. kondoi populations with moderate resistance (10-40-fold) to three different insecticide groups: organophosphates, carbamates and pyrethroids. However, A. kondoi populations showed no resistance to the butenolide, flupyradifurone. We were unable to identify general metabolic mechanisms using synergist assays (cytochromes P450, glutathione S-transferases, or esterases), indicating that further detailed molecular investigations to characterise the putative resistance mechanism are needed.

CONCLUSION

Insecticide-resistant A. kondoi present an emerging challenge to Australian agriculture. Growers require new tools and updated strategies, including access to newer chemistries, to alleviate their reliance on the few insecticides currently registered against A. kondoi. The implications of insecticide resistant A. kondoi for future management, the potential mechanisms of resistance, and future research priorities are discussed. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Aphid populations are frequently infected with facultative endosymbionts

The occurrence of facultative endosymbionts has been studied in many commercially important crop pest aphids, but their occurrence and effects in non-commercial aphid species in natural populations have received less attention. We screened 437 aphid samples belonging to 106 aphid species for the eight most common facultative aphid endosymbionts. We found one or more facultative endosymbionts in 53% (56 of 106) of the species investigated. This likely underestimates the situation in the field because facultative endosymbionts are often present in only some colonies of an aphid species. Oligophagous aphid species carried facultative endosymbionts significantly more often than monophagous species. We did not find a significant correlation between ant tending and facultative endosymbiont presence. In conclusion, we found that facultative endosymbionts are common among aphid populations. This study is, to our knowledge, the first of its kind in the Netherlands and provides a basis for future research in this field. For instance, it is still unknown in what way many of these endosymbionts affect their hosts, which is important for determining the importance of facultative endosymbionts to community dynamics.

Genetic Variation of Turnip Yellows Virus in Arable and Vegetable Brassica Crops, Perennial Wild Brassicas, and Aphid Vectors Collected from the Plants

Turnip yellows virus (TuYV; Polerovirus, Solemoviridae) infects and causes yield losses in a range of economically important crop species, particularly the Brassicaceae. It is persistently transmitted by several aphid species and is difficult to control. Although the incidence and genetic diversity of TuYV has been extensively investigated in recent years, little is known about how the diversity within host plants relates to that in its vectors. Arable oilseed rape (Brassica napus) and vegetable brassica plants (Brassica oleracea), wild cabbage (B. oleracea), and aphids present on these plants were sampled in the field in three regions of the United Kingdom. High levels of TuYV (82 to 97%) were detected in plants in all three regions following enzyme-linked immunosorbent assays. TuYV was detected by reverse transcription polymerase chain reaction in Brevicoryne brassicae aphids collected from plants, and TuYV sequences were obtained. Two TuYV open reading frames, ORF0 and ORF3, were partially sequenced from 15 plants, and from one aphid collected from each plant. Comparative analyses between TuYV sequences from host plants and B. brassicae collected from respective plants revealed differences between some ORF0 sequences, which possibly indicated that at least two of the aphids might not have been carrying the same TuYV isolates as those present in their host plants. Maximum likelihood phylogenetic analyses including published, the new TuYV sequences described above, 101 previously unpublished sequences of TuYV from oilseed rape in the United Kingdom, and 13 also previously unpublished sequences of TuYV from oilseed rape in Europe and China revealed three distinct major clades for ORF0 and one for ORF3, with some distinct subclades. Some clustering was related to geographic origin. Explanations for TuYV sequence differences between plants and the aphids present on respective plants and implications for the epidemiology and control of TuYV are discussed.

Manipulating multi-level selection in a fungal entomopathogen reveals social conflicts and a method for improving biocontrol traits

Changes in parasite virulence are commonly expected to lead to trade-offs in other life history traits that can affect fitness. Understanding these trade-offs is particularly important if we want to manipulate the virulence of microbial biological control agents. Theoretically, selection across different spatial scales, i.e. between- and within-hosts, shapes these trade-offs. However, trade-offs are also dependent on parasite biology. Despite their applied importance the evolution of virulence in fungal parasites is poorly understood: virulence can be unstable in culture and commonly fails to increase in simple passage experiments. We hypothesized that manipulating selection intensity at different scales would reveal virulence trade-offs in a fungal pathogen of aphids, Akanthomyces muscarius. Starting with a genetically diverse stock we selected for speed of kill, parasite yield or infectivity by manipulating competition within and between hosts and between-populations of hosts over 7 rounds of infection. We characterized ancestral and evolved lineages by whole genome sequencing and by measuring virulence, growth rate, sporulation and fitness. While several lineages showed increases in virulence, we saw none of the trade-offs commonly found in obligately-killing parasites. Phenotypically similar lineages within treatments often shared multiple single-nucleotide variants, indicating strong convergent evolution. The most dramatic phenotypic changes were in timing of sporulation and spore production in vitro. We found that early sporulation led to reduced competitive fitness but could increase yield of spores on media, a trade-off characteristic of social conflict. Notably, the selection regime with strongest between-population competition and lowest genetic diversity produced the most consistent shift to early sporulation, as predicted by social evolution theory. Multi-level selection therefore revealed social interactions novel to fungi and showed that these biocontrol agents have the genomic flexibility to improve multiple traits-virulence and spore production-that are often in conflict in other parasites.

Global phylogenetic analysis of soybean dwarf virus isolates and their associations with aphid vectors and severe disease in soybeans

Soybean dwarf virus (SbDV) was first described in Japan as an agent of severe soybean disease transmitted by the foxglove aphid, Aulacorthum solani, with separable yellowing (Y) and dwarfing (D) strains. SbDV of both Y and D genotypes were later documented in other countries. For three decades, SbDV isolates were assessed to evaluate risk to U.S. soybean production. U.S. SbDV isolates were transmitted by the pea aphid Acyrthosiphum pisum and showed limited disease in soybeans, suggesting it was not a major threat to U.S. soybean production. Here we report 21 new full-length SbDV genome sequences including those of the originally described Japanese Y and D isolates, isolates from Syria and New Zealand associated with severe disease, and 17 isolates from U.S. field collections. Using these new full-length genomes, a global phylogeny was assembled and used to revisit risk assessment based on sequence similarities, isolate pathogenicity, and vector specificity.

Interspecific recognition based on cuticular hydrocarbons mediates reproduction control in aphids

The preset study tested whether an aphid species can control its reproduction by recognizing the presence and density of a rival species. Acyrthosiphon pisum and Megoura crassicauda often coexist on the same leguminous plant. We established clonal colonies from each species and mixed colonies with one A. pisum and one M. crassicauda adult. There were no significant differences in the population growth patterns of the two species at 20 °C. However, mixed colonies increased faster and attained larger colony sizes than the clonal colonies. Thus, positive interspecific interactions were confirmed. A mixed colony was dominated by the members of a clone that produced a greater number of newborns in the initial stage, irrespective of the species. Thus, we confirmed the priority effect in the interspecific competition. To simulate the priority effect, 15 glass beads coated with the hexane extract of M. crassicauda aphids were attached to a cut leaf, to which one A. pisum adult was transferred. The presence of the hexane extract of M. crassicauda greatly reduced the reproductive rate of A. pisum adults. We conclude that aphids can control their reproduction by evaluating the relative density of rivals to fellow aphids based on the cuticular hydrocarbons.

Exploration of culturable bacterial associates of aphids and their interactions with entomopathogens

Aphids shelter several bacteria that benefit them in various ways. The associates having an obligatory relationship are non-culturable, while a few of facultative associates are culturable in insect cell lines, axenic media or standard microbiology media. In the present investigation, isolation, and characterization of the culturable bacterial associates of various aphid species, viz., Rhopalosiphum maidis, Rhopalosiphum padi, Sitobion avenae, Schizaphis graminum, and Lipaphis erysimi pseudobrassicae were carried out. A total of 42 isolates were isolated using different growth media, followed by their morphological, biochemical, and molecular characterization. The isolated culturable bacterial associates were found to belong to the genera Acinetobacter, Bacillus, Brevundimonas, Cytobacillus, Fictibacillus, Planococcus, Priestia, Pseudomonas, Staphylococcus, Sutcliffiella, and Tumebacillus which were grouped under seven families of four different orders of phyla Bacillota (Firmicutes) and Pseudomonata (Proteobacteria). Symbiont-entomopathogen interaction study was also conducted, in which the quantification of colony forming units of culturable bacterial associates of entomopathogenic fungal-treated aphids led us to the assumption that the bacterial load in aphid body can be altered by the application of entomopathogens. Whereas, the mycelial growth of entomopathogens Akanthomyces lecanii and Metarhizium anisopliae was found uninhibited by the bacterial associates obtained from Sitobion avenae and Rhopalosiphum padi. Analyzing persistent aphid microflora and their interactions with entomopathogens enhances our understanding of aphid resistance. It also fosters the development of innovative solutions for agricultural pest management, highlighting the intricate dynamics of symbiotic relationships in pest management strategies.

The effects of insecticide seed treatments on the parasitism and predation of Myzus persicae (Homoptera: Aphididae) in canola

The green peach aphid, Myzus persicae (Sulzer) (Homoptera: Aphididae), is a major pest of brassica plants, with the ability to transmit > 100 viruses. Although the adoption of Integrated Pest Management is increasing, chemical treatment remains the predominant method used to control M. persicae globally. Insecticide seed treatments, typically with neonicotinoid active ingredients, have become commonplace in canola crops, and are viewed as a "softer" alternative to foliar sprays but may nevertheless impact natural enemies of M. persicae. In this study, the effects of canola seed treatments, containing imidacloprid, thiamethoxam, and a mixture of thiamethoxam + lambda-cyhalothrin, were investigated on the parasitoid wasp, Aphidius colemani Viereck (Hymenoptera: Braconidae) and the green lacewing, Mallada signatus (Schneider) (Neuroptera: Chrysopidae), both important natural enemies of M. persicae. Laboratory trials were undertaken using whole plants, with lethal and sublethal effects assessed by measuring several traits. Compared with untreated plants, more aphid mummies were produced and more A. colemani were reared on plants treated with thiamethoxam + lambda-cyhalothrin and more aphid mummies were produced on imidacloprid plants. Imidacloprid reduced the time A. colemani spent searching for M. persicae and thiamethoxam reduced its cleaning time. However, after A. colemani were removed from treated plants, there were no such effects observed, suggesting these impacts were relatively short-lived. We found no significant effects of seed treatments on M. signatus. These results point to the complexity of ecotoxicology studies involving multiple trophic levels and indicate that seed treatments may have variable impacts on key fitness traits of natural enemies.

Novel heptafluoroisopropyl N-phenylpyrazole aryl amides containing cyanoalkyl groups: Design, synthesis, insecticidal activity, docking studies and theoretical calculations

To discover and develop new insecticides of the phenylpyrazole class, a series of heptafluoroisopropyl N-phenylpyrazole aryl amide compounds bearing cyanoalkyl groups were synthesized based on the lead compound nicofluprole. Their structures were established by HRMS, 1H NMR and 13C NMR. Bioassay results indicated that several of these compounds exhibited remarkable acaricidal and insecticidal activities. The LC50 values for compounds A1, A2 and A5 against Tetranychus cinnabarinus (T. cinnabarinus) were 1.7-4.2 times lower than that of nicofluprole (3.124 mg/L). Compounds A1, A2, A4 and A7 against Myzus persicae (M. persicae) had LC50 values of 0.261, 1.292, 0.589 and 1.133 mg/L respectively, exceeding that of nicofluprole (LC50 = 4.200 mg/L). Some compounds also demonstrated good insecticidal activity against Plutella xylostella (P. xylostella). For example, compounds A1-A4, A6, and A7 had a mortality rate of 100 % at a low concentration of 1.25 mg/L, which was comparable to nicofluprole (93.3%). Compound A1 exhibited insecticidal activity against Chilo suppressalis (C. suppressalis) with an LC50 value of 2.271 mg/L, which was superior to both nicofluprole (6.021 mg/L) and the positive control broflanilide (6.895 mg/L). Taking compound A5 as a representative, we tested the insecticidal activity against Aphis fabae (A. fabae), Aphis gossypii Glover (A. gossypii Glover), Nilaparvata lugens (N. lugens) and Laodelphax striatellus (L. striatellus) at 10 mg/L, and our results revealed that compound A5 exhibited broad-spectrum insecticidal activity. Molecular docking studies suggested that A1 had a lower binding energy of -7.764 kcal/mol with the P. xylostella gamma-aminobutyric acid receptors (GABAR). Density functional theory calculations (DFT) provided insights into the design of new compounds. This research suggested that the novel phenylpyrazoles featuring cyanoalkyl moieties in this work hold potential as novel insecticides for further research and development.

Design, Synthesis, and Synergistic Activities of Eight-Membered Carbon Bridged Neonicotinoid Derivatives

Insecticide synergists are an effective approach to increase the control efficacy and reduce active ingredient usage. In order to explore neonicotinoid-specific synergists with novel scaffolds and higher potency, a series of eight-membered carbon bridged neonicotinoid derivatives were designed and synthesized in accordance with our previous research. The synergistic effects of the target compounds on neonicotinoids in Aphis craccivora were evaluated, and the structure-activity relationships were summarized. The results indicated that most of the target compounds exhibited significant synergistic effects on imidacloprid in A. craccivora at low concentrations. In particular, compound 1 at a concentration of 1 mg/L reduced the LC50 value of imidacloprid from 0.856 mg/L to 0.170 mg/L. Meanwhile, compound 1 also increased the insecticidal activity of most neonicotinoid insecticides belonging to the Insecticide Resistance Action Committee (IRAC) 4 A subgroup against A. craccivora. The present study might be meaningful for directing the design of neonicotinoid-specific synergists.

Old and New Aphid-Borne Viruses in Coriander in Chile: An Epidemiological Approach

In Chile, edible herbs are mainly grown by small farmers. This type of horticultural crop typically requires intensive management because it is highly susceptible to insects, some of which transmit viruses that severely affect crop yield and quality. In 2019, in coriander plants tested negative for all previously reported viruses, RNA-Seq analysis of one symptomatic plant revealed a plethora of viruses, including one virus known to infect coriander, five viruses never reported in coriander, and a new cytorhabdovirus with a 14,180 nucleotide RNA genome for which the species name Cytorhabdovirus coriandrum was proposed. Since all the detected viruses were aphid-borne, aphids and weeds commonly growing around the coriander field were screened for viruses. The results showed the occurrence of the same seven viruses and the alfalfa mosaic virus, another aphid-borne virus, in aphids and weeds. Together, our findings document the presence of multiple viruses in coriander and the potential role of weeds as virus reservoirs for aphid acquisition.

Markers of resistance to pea aphid, Acyrthosiphon pisum Harris in Pisum sativum L. accessions

One of the major insect pests in Pisum sativum L. (is Acyrthosiphon pisum Harris (Hemiptera: pests in Pisum sativum L. (Hemiptera: Aphididae) is Acyrthosiphon pisum Harris (Hemiptera: Aphididae). An effective strategy for aphid control is the resistant host plant use. The current study aimed to identify resistance mechanisms and assess biochemical and morphological markers of pea aphid resistance in pea accessions. Meteorological variables affected the pea aphid density, which positively correlated with temperature, while precipitation amount and humidity negatively impacted. The aphid number was significantly and positively associated with the leaf area and the nitrogen content but negatively correlated with calcium and phosphorus levels. The pea aphid-resistant cultivars L 123-7-11, L 128-1and L 125-5 had small leaf areas, and high phosphorus and calcium content but a low nitrogen level. In the mutual influence of the plant indicators, phosphorus concentration had the highest negative impact on pea aphid density, followed by calcium. The plant marker inclusion in the pea breeding process is an efficient tool for a substantial selection program improvement for aphid resistance. Therefore, resistant host plants are essential tools promoting considerable selection program improvement for aphid resistance in the P. sativum breeding process and helping develop sustainable and environmentally friendly agriculture.

Analysis of gut microbiota of ladybug beetle (Harmonia axyridis) after feeding on different artificial diets

BACKGROUND

Harmonia axyridis is an effective natural enemy insect to a variety of phloem-sucking pests and Lepidopteran larvae, such as aphids, scabies, and phylloxera, while its industrial production is limited due to unmature artificial diet. Insect intestinal microbiota affect host development and reproduction. The aim of this study is to understand intestinal microbiota composition of H. axyridis and screen effective probiotics on artificial diet. Considering the role of the components and composition of the diet on the structure and composition of the intestinal microbiome, four kinds of diets were set up: (1) aphid; (2) basic diet; (3) basic diet + glucose; (4) basic diet + trehalose. The gut microbiota of H. axyridis was detected after feeding on different diets.

RESULTS

Results showed that the gut microbiota between artificial diet group and aphid groups were far apart, while the basic and glucose groups were clearly clustered. Besides, the glucose group and trehalose group had one unique phylum, Cryptophyta and Candidatus Saccharibacteria, respectively. The highest abundance of Proteobacteria was found in the aphid diet. The highest abundance of Firmicutes was found in the basic diet. However, the addition of glucose or trehalose alleviated the change. In addition, the relative abundance of Enterobacter, Klebsiella, Enterobacteriaceae_unclassified, Enterobacteriales_unclassified and Serratia in the aphid group was higher than other groups. Moreover, the function of gut genes in each group also showed clear differences.

CONCLUSION

These results have offered a strong link between artificial diets and gut microbes, and also have provided a theoretical basis for the screening of synergistic probiotics in artificial diet.

Stable composition of gut microbiome in the Asian ladybeetle Coccinella septempunctata reared on natural and artificial diets

The Asian ladybeetle, Coccinella septempunctata, is an important insect of predatory natural enemy, which has a strong control effect and application prospects for aphids, whiteflies, mealybugs, and other small-sized pests of agriculture and forestry crops. Gut microbiota composition posed impacts on development of insects. In order to clarify the effect of artificial feed feeding on the intestinal microbial species and structure of C. septempunctata, we compared the intestinal microbial flora of C. septempunctata reared on bean aphids and artificial food for 15 days. Results show that Proteobacteria was the dominant component in all groups at phylum level, Rhodobacter, Methylovigula, Burkholderia, and Bradyrhizobium were the dominant bacteria among all groups at genus level. As to the differences in bacterial community structure and diversity, there is no significant difference between Shannon index and Simpson index, the principal components analysis of the bacterial communities, and the samples were roughly distributed in different regions. After 15 days of feeding, artificial diet did not significantly reduce the microbial diversity of the gut of C. septempunctata compared to the aphid group, and there was no significant effect on the abundance of dominant flora in the gut of C. septempunctata, C. septempunctata gut has a similar core microbiota. This study clarifies the effects in intestinal microbial diversity and composition structure of the C. septempunctata with artificial diet, and provides a theoretical basis for understanding the intestinal microorganisms and optimizating the artificial diet of C. septempunctata.

Report of Citrus tristeza virus in Diaphorina citri (Hemiotera: Liviidae) insects of different sexes, color morphs, and developmental stages

Diaphorina citri, also known as the Asian citrus psyllid, is the main vector of 'Candidatus Liberibacter asiaticus' (CLas) associated with citrus Huanglongbing. It has been reported that D. citri could also be infected by Citrus tristeza virus (CTV), a virus that has been previously reported to be vectored by certain aphid species. In this study, the CTV and CLas profiles in different organs, color variants, developmental stages, or sexes of D. citri insects were analyzed. Although no significant differences were found between nymphs and adults in CTV titers, we found that the third instar nymph of D. citri was more efficient in CTV and CLas acquisition compared to the fourth and fifth instars and adults. With the instars of D. citri development, the relationship between the acquiring of CTV and CLas by D. citri seemed to follow an inverse trend, with the titer of CLas increased and the titer of CTV decreased. No significant differences were observed between the 2 sexes of D. citri in acquiring either CTV or CLas titers in the field. However, no differences were drawn among the 3 color morph variants for CTV titers. CTV titers in the midguts of adult D. citri were significantly higher than those in the salivary glands. Both CTV-positive incidence and CTV titers in the midguts of adult D. citri increased with increasing exposure periods. This study provides new data to deepen our understanding of the CTV-involved interaction between D. citri and CLas.

Bioactive compounds from Retama raetam (Forssk.) Webb & Berthel. and their insecticidal activity against cotton pests Aphis gosspyii and Amrasca biguttula

Cotton aphids, Aphis gosspyii and cotton jassids, Amrasca biguttula are destructive piercing sucking pests to many strategic crops, especially cotton, not only in Egypt but also all over the world. Using synthetic pesticides to control these pests led to several deleterious impacts. Natural pesticides can be used as a harmless alternative. Nine compounds were isolated from different fractions of Retama raetam using chromatographic techniques and identified by spectroscopic methods as eugenol (1), alpinumisoflavone (2), licoflavone C (3), ephedroidin (4), anagyrine (5), spartiene (6), genistein-8β-C-glucoside (7), isoprunetin (8) and isoprunetin 7-O-β-D-glucopyranoside (9). The methanol crude extract and its fractions (hexane, chloroform, ethyl acetate and butanol), as well as the isolated compounds were examined against A. gosspyii and A. biguttula as insecticides. The results showed that chloroform fraction was the most potent fraction against A. gosspyii and A. biguttula, with LC50 values of 65.66 and 64.43 ppm, respectively. As well, compounds 1, 5 and 6 were found to be more active, with LC50 values of 69.84, 25.49 and 27.22 ppm for A. gosspyii and 65.17, 24.07 and 24.78 ppm for A. biguttula, respectively. The most potent compounds (1, 5 and 6) exhibited AChE inhibition toward A. gosspyii compared with the control. So, it can be concluded that the isolated compounds eugenol 1, anagyrine 5 and spartiene 6 are the active principles due to their capability to inhibit AchE activity.

Experimental Transmission of Plant Viruses by Aphids or Whiteflies

Numerous species of plant viruses are naturally transmitted by insect vectors, mainly homopterans like aphids and whiteflies. Depending on the vector specificity and the mode of transmission, different durations of the periods for acquisition, retention, and inoculation are required for a successful transmission. Therefore, the experimental setup to perform controlled transmission experiments under laboratory conditions involves handling the vector organisms and managing the times for the different steps of the process to optimize and standardize the results. This chapter describes some basic procedures that can be applied to vector-mediated transmission experiments with selected viruses using aphids or whiteflies and different host plants.

Coordinated recruitment of conserved defense-signaling pathways in PVYO-Infected Nicotiana benthamiana

Potato virus Y (PVY) is an aphid-transmitted potyvirus that affects economically important solanaceous species. In this study, the phenomena and mechanisms following infection with PVY were investigated in tobacco (Nicotiana benthamiana). In tobacco plants, infection with a mild strain of PVY (PVYO) induced stunted growth in the first two leaves at the shoot apex starting 7 days post-infection (dpi), and mosaic symptoms began to appear on newly developing young leaves at 14 dpi. Using enzyme-linked immunosorbent assay and ultrastructure analysis, we confirmed that viral particles accumulated only in the upper developing leaves of infected plants. We analyzed reactive oxygen species (ROS) generation in leaves from the bottom to the top of the plants to investigate whether delayed symptom development in leaves was associated with a defense response to the virus. In addition, the ultrastructural analysis confirmed the increase of ATG4 and ATG8, which are autophagy markers by endoplasmic reticulum (ER) stress, and the expression of genes involved in viral RNA suppression. Overall, our results suggested that viral RNA silencing and induced autophagy may play a role in the inhibition of viral symptom development in host plants in response to PVYO infection.

New material of Euroleptochromus tuberculatus Yin & Cai (Coleoptera: Staphylinidae: Scydmaeninae) in Eocene Baltic amber

The extinct members of the ant-like stone beetle supertribe Mastigitae are among the best studied groups of all fossil Scydmaeninae, and their evolutionary history can be traced from the latest Albian to the earliest Cenomanian through Miocene/Oligocene, with seven extinct genera being described (summarized in Jaoszyski, 2016; Jaoszyski & Perkovsky, 2016; Jaoszyski et al., 2018; Ross, 20192022 (list of Burmese amber taxa)).

Third new fossil species of the genus Ephedrus Haliday, 1833 (Hymenoptera: Braconidae: Aphidiinae) from Baltic amber

A new species of aphid parasitoid from the genus Ephedrus Haliday, E. zaikai Davidian, sp. nov. (Braconidae: Aphidiinae), is described and illustrated from Late Eocene Baltic amber. This new species was compared with described fossil taxa Ephedrus mirabilis Timon-David, 1944 (Oligocene imprint from Bassin de Marseille), Ephedrus carsteni Davidian, 2023 and E. primordialis Brues, 1933 (both from Eocene Baltic amber), and E. rasnitsyni Davidian & Kaliuzhna, 2021 (Eocene Sakhalinian amber), as well as with extant E. niger Gautier, Bonnamour & Gaumont, 1929 and E. chaitophori Grdenfors, 1986.

Review and new data on the aphid fauna (Hemiptera, Aphidoidea) of the Socialist Republic of Vietnam with a description of a new genus and a new species of the family Hormaphididae

An up-to-date information on aphid fauna (Hemiptera, Aphidoidea) of Vietnam based on literature data and original material is presented. The updated check-list of aphids includes 47 species, and also 15 species identified only to genus level. Protastegopteryx vietnamensis gen. nov., sp. nov. from Bambusa sp., collected in Ct Tin National Park (Dong Nai Province), is described. The species is illustrated and its biometric data is provided. The described aphid genus is closely related to Astegopteryx Karsch, 1890. The taxonomic position of the genus is discussed.

Part-night exposure to artificial light at night has more detrimental effects on aphid colonies than fully lit nights

Artificial light at night (ALAN) threatens natural ecosystems globally. While ALAN research is increasing, little is known about how ALAN affects plants and interactions with other organisms. We explored the effects of ALAN on plant defence and plant-insect interactions using barley (Hordeum vulgare) and the English grain aphid (Sitobion avenae). Plants were exposed to 'full' or 'part' nights of 15-20 lux ALAN, or no ALAN 'control' nights, to test the effects of ALAN on plant growth and defence. Although plant growth was only minimally affected by ALAN, aphid colony growth and aphid maturation were reduced significantly by ALAN treatments. Importantly, we found strong differences between full-night and part-night ALAN treatments. Contrary to our expectations, part ALAN had stronger negative effects on aphid colony growth than full ALAN. Defence-associated gene expression was affected in some cases by ALAN, but also positively correlated with aphid colony size, suggesting that the effects of ALAN on plant defences are indirect, and regulated via direct disruption of aphid colonies rather than via ALAN-induced upregulation of defences. Mitigating ecological side effects of ALAN is a complex problem, as reducing exposure to ALAN increased its negative impact on insect herbivores. This article is part of the theme issue 'Light pollution in complex ecological systems'.

Macrosiphoniella (Asterobium) herczeki sp. nov.a new aphid species from Bulgaria (Hemiptera, Aphididae)

Here we present a description of a new aphid species from the subgenus Asterobium Hille Ris Lambers, 1938 of the genus Macrosiphoniella Del Guercio, 1911 in the tribe Macrosiphini Wilson, 1910 (Aphididae). The new speciesMacrosiphiniella (Asterobium) herczeki sp. nov. living on Galatella villosa (Asteraceae) in Tolbuchin region, Bulgaria, is described based on apterous viviparous females. The new species is morphologically similar to M. (Asterobium) konyratica Kadyrbekov, 2018 from Kazakhstan from which it differs in several morphological and metric characters. We provided an updated key to Blackmans & Eastop online key to Aster-feeding aphids.

Suppression of weed and insect populations by living and straw mulches in sesame (Sesamum indicum L.)

In order to evaluate the effect of different weed management treatments on weeds, pest and natural enemies populations in sesame (Sesamum indicum L.), a 2-year study was conducted in East Azarbaijan, Iran in 2020-2021. The study was conducted based on randomized complete block design with four replications. The weed management treatments consisted of trifluralin use (960 g ai ha-1), wheat straw mulch (WSM), living mulches of fenugreek (Trigonella foenum-graecum L.) (FLM), bitter vetch (Vicia ervilia L.) (VLM), calendula (Calendula officinalis L.) (CLM) and one-time hand weeding (OHW). The effect of weed management treatment was significant on densities of insect pests, natural enemies and weed and also weed biomass and sesame seed yield. The lowest densities of insect pests including Myzus persicae, Brevicoryne brassicae, Helicoverpa armigera and Spodoptera exigua were observed in CLM treatment. Also, the highest densities of natural enemies Coccinella septompunctata, Coccinella undecimpunctata and Orius niger were observed in CLM treatment. The highest reductions in grass (51.0%), broadleaf (72.0%), and total (62.6%) weed biomasses and highest seed yield (1456 kg ha-1) were obtained in OHW. The seed yields in CLM and WSM treatments were not significantly different with trifluralin treatment and could be recommended in sustainable production of sesame.

The first description of an apterous aphid morph of the family Canadaphididae (Hemiptera, Sternorrhyncha, Aphidomorpha)

The first apterous morph of the Canadaphididae family is described based on Canadian amber inclusions. On the basis of morphological features, it was assigned to the species Canadaphis carpenteri. For the first time, a fluorescence microscope was used to examine a representative of the Canadaphididae family, revealing previously unknown details.

Effects of dimpropyridaz on feeding behavior, locomotivity and biological parameters of Aphis gossypii

Aphis gossypii is a worldwide agricultural pest insect that has developed resistance to multiple pesticides. Dimpropyridaz is a new chordotonal organ regulator and has been registered for control of sap-sucking insects including A. gossypii. For the aim to effectively apply dimpropyridaz for A. gossypii control, it is necessary to clarify the toxic effects of dimpropyridaz on cotton aphids. In the present study, the effects of dimpropyridaz on feeding behavior, locomotivity and biological parameters of A. gossypii were investigated. The bioassay results showed that dimpropyridaz had good insecticidal activity against A. gossypii, with LC50 as 1.91 mg/L at 72 h post exposure. Moreover, the dimpropyridaz treated A. gossypii showed obvious poisoning symptoms of dehydration and shrivel. Through the gentle-touch experiment and feeding experiment, it was found that dimpropyridaz treatment had significant adverse impacts on the locomotivity and feeding behavior of A. gossypii. Compared with the control group, the coordinated movement ability of the treated A. gossypii attenuated, moreover the feeding behavior of A. gossypii was inhibited. The feeding rate decreased by 62.00%, 64.00% and 71.67% after treatment with 50.33 mg/L dimpropyridaz for 24 h, 48 h and 72 h, respectively. Especially, EPG recordings showed that the number of intracellular stylet puncture and the total duration of phloem sap ingestion and concurrent salivation decreased substantially, while the total duration of non-probing increased after exposure to dimpropyridaz. Furthermore, the treatments with LC10 and LC30 of dimpropyridaz significantly reduced the longevity and fecundity of F0, and led to a decrease of the relative fitness of F0 to 0.48 and 0.32, respectively. The net reproductive rate (R0) and mean generation time (T) of F1 generation were also significantly reduced, moreover the duration of reproduction was significantly shortened. In addition, at 72 h post treatment with LC30 dimpropyridaz, the gene expression levels of JHEH and USP of cotton aphids significantly increased, while the expression of FOXO, INR, EcR and INRS decreased. These results provide basis for clarifying the toxicology of dimpropyridaz to cotton aphids, and also are beneficial for effective control of cotton aphid using dimpropyridaz.

GhMYC1374 regulates the cotton defense response to cotton aphids by mediating the production of flavonoids and free gossypol

Myelocytomatosis (MYC) transcription factors (TFs) in plants are well-known regulators of plant defense against herbivores. However, the role and mechanism of MYC TFs in cotton (Gossypium hirsutum L.) defense against cotton aphids (Aphis gossypii Glover) remain still elusive. Herein, on the basis of aphid-induced cotton transcriptome analysis, GhMYC1374, a cotton MYC2-like TF that was highly induced by cotton aphid attack, has been identified that confers cotton aphid resistance in cotton. GhMYC1374 was an intranuclear transcription factor with three domains: bHLH-MYC_N, RBR and bHLH_AtAIB_like. GhMYC1374 was induced under cotton aphid feeding, exogenous methyl jasmonate (MeJA) and salicylic acid (SA) treatments. GhMYC1374 transient overexpression in cotton plants enhanced cotton aphid-resistance, while GhMYC1374 silence through VIGS (virus induced gene silencing) decreased cotton aphid-resistance. GhMYC1374 transient overexpression of in cotton plants activated the phenylpropane pathway and promoted the synthesis of flavonoids, and resistance to thus enhanced the cotton resistance against aphids. In contrast, GhMYC1374 silence inhibited the biosynthesis of flavonoids. In addition, GhMYC1374 also positively activated the expression of the biosynthetic genes of free gossypol, leading to the high content of free gossypol. Taken together, our results suggest that GhMYC1374 is involved in the cotton defense response against cotton aphids by regulating the biosynthesis of flavonoids and free gossypol.

Endosymbionts modulate virus effects on aphid-plant interactions

Vector-borne pathogens frequently modify traits of their primary hosts and vectors in ways that influence disease transmission. Such effects can themselves be altered by the presence of other microbial symbionts, yet we currently have limited understanding of these interactions. Here we show that effects of pea enation mosaic virus (PEMV) on interactions between host plants and aphid vectors are modulated by the presence of different aphid endosymbionts. In a series of laboratory assays, we found strong interactive effects of virus infection and endosymbionts on aphid metabolomic profiles, population growth, behavior, and virus transmission during aphid feeding. Furthermore, the strongest effects-and those predicted to favor virus transmission-were most apparent in aphid lines harboring particular endosymbionts. These findings show that virus effects on host-vector interactions can be strongly influenced by other microbial symbionts and suggest a potentially important role for such interactions in disease ecology and evolution.