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Pratylenchus neglectus and P. thornei are among the most destructive root lesion nematodes of wheat in the Pacific Northwest, United States of America and throughout the world. The aim of this study was to determine whether both nematode species were similar in their ability to induce defense genes in roots of wheat genotype Scarlet, and whether a combination of both species induced a different pattern of gene induction than each species alone. The long-term aspect of the research was to identify nematode-inducible promoters for deploying defense genes in roots in breeding programs. The root transcriptomes of genotype Scarlet were obtained after a one-week infection period with each nematode species separately, or both species combined. Root defense gene expression was induced for all three treatments relative to the no-nematode control, but P. thornei affected expression to a greater extent compared to P. neglectus. The species combination induced the highest number of defense genes. This result was not predicted from nematode enumeration studies, in which P. thornei colonization was substantially lower than that of P. neglectus, and the nematode combination did not show a significant difference. Quantitative real time polymerase chain reaction (qRT-PCR) assays for Dehydrin2, Glucan endo-1,3-beta-glucosidase, 1-cys-Peroxiredoxin, Pathogenesis-related protein 1 and Late embryogenesis-abundant proteins 76 and group 3 authenticated the induction observed in the transcriptome data. In addition, a near-isogenic line of Scarlet harboring genetic resistance to fungal soilborne pathogens, called Scarlet-Rz1, showed similar or higher levels of defense gene expression compared to fungus-susceptible Scarlet in qRT-PCR assays. Finally, transcriptome expression patterns revealed nematode-inducible promoters that are responsive to both P. neglectus and P. thornei., Competing Interests: The authors have declared that no competing interests exist., (Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.)

Sitobion miscanthi , the main species of wheat aphids, is one kind of harmful pest. Chemical insecticides are the important agrochemical products to effectively control wheat aphids. However, the broad application has led to serious resistance of pests to several insecticides, and understanding insecticide resistance mechanisms is critical for integrated pest management. In this study, SmUGGT1 , a new uridine diphosphate (UDP)-glycosyltransferase ( UGT ) gene, was cloned and more strongly expressed in the SM-R (the resistant strain to imidacloprid) than in the SM-S (the susceptible strain to imidacloprid). The increased susceptibility to imidacloprid was observed after silencing SmUGGT1 , indicating that it can be related to the resistance to imidacloprid. Subsequently, SmUGGT1 regulated post-transcriptionally in the coding sequences (CDs) by miR-81 was verified and involved in the resistance to imidacloprid in S. miscanthi . This finding is crucial in the roles of UGT involved in insecticide resistance management in pests.

As an economically important plant parasitic nematode (PPN), Heterodera filipjevi causes great damage on wheat, and now it was widely recorded in many countries. While multiple genomes of PPNs have been published, high-quality genome assembly and annotation on H. filipjevi have yet to be performed. This study presents a chromosome-scale genome assembly and annotation for H. filipjevi, utilizing a combination of Illumina short-read, PacBio long-read, and Hi-C sequencing technologies. The genome consists of 9 pseudo-chromosomes that contain 134.19 Mb of sequence, with a scaffold N50 length of 11.88 Mb. In total, 10,036 genes were annotated, representing 75.20% of the total predicted protein-coding genes. Our study provides the first chromosome-scale genome for H. filipjevi, which is also the inaugural high-quality genome of cereal cyst nematodes (CCNs). It provides a valuable genomic resource for further biological research and pest management of cereal cyst nematodes disease., (© 2024. The Author(s).)

The number, timing, and fitness of colonizing parasitoids in fields of ephemeral crops often depend on factors external to the fields. We investigated cereal aphid parasitism in 23 winter wheat fields using sentinel plants infested with bird cherry-oat aphids, Rhopalosiphum padi (L.) (Hemiptera: Aphididae), and we investigated the effect of parasitoids on cereal aphid population growth using exclusion and parasitoid-accessible cages infested with bird cherry-oat aphids. Lysiphlebus testaceipes (Cresson) (Hymenoptera: Braconidae), Aphelinus nigritus (Howard) (Hymenoptera: Aphelinidae), and Diaeretiella rapae (McIntosh) (Hymenoptera: Braconidae), in decreasing order of abundance, parasitized R. padi on sentinel plants. The mean percent parasitism in parasitoid-accessible cages was 5.2% in autumn and 35.0% in spring. Aphid population intensity was greater in complete exclusion than in parasitoid-accessible cages. Measures of landscape composition and configuration were quantified, and aphid parasitism in autumn by L. testaceipes and A. nigritus was positively associated with % landcover by summer crops and patch density. Parasitism by both species was negatively associated with contagion and % woodlands. Parasitism during spring was positively associated with % grassland and fractal dimension and negatively associated with % canola. The number of braconid mummies per sentinel plant was positively correlated to the number of braconid mummies on wheat stems from parasitoid-accessible cages. Results indicate that cereal aphid mortality caused by parasitoids and their ability to exert effective biological control is related to landscape structure. Comparing this study to an earlier study in the same agroecosystem demonstrated temporal stability of the landscape influence on aphid parasitism by L. testaceipes in winter wheat., (Published by Oxford University Press on behalf of Entomological Society of America 2024.)

The wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), is a major pest of wheat (Triticum aestivum L., Poales: Poaceae) across the northern Great Plains of North America. Cephus cinctus has a wide host range, attacking numerous wild grasses and cultivated cereals in crop and grassland habitats, where it is, in turn, attacked by 2 native braconid parasitoids. Quantitative assessments of C. cinctus infestation and parasitism levels in different grass species across the full spectrum of available hosts are important in assessing the extent to which grasslands, or specific constituent grass species, may be reservoirs of pests or parasitoids moving into wheat. We quantified infestation and parasitism levels in over 25,000 stems collected from 17 grass species and wheat spanning 35 sites in central Montana, United States, over 2 yr. Infestation levels in 5 grass species, primarily wheatgrasses, were high (38%-65%) and similar to the levels observed in wheat (55%). In contrast, the majority of grass species (12 of 17) had significantly lower levels of infestation (<10%), suggesting that most grasses are not important reservoirs of C. cinctus. Parasitism levels in highly infested wheatgrasses were, on average, 3 times higher than those in cultivated wheat, suggesting that these grasses could provide important conservation habitat for parasitoids. Future work examining the relative performance of pests and parasitoids in these grasses will be important in gauging their relative value as plant materials to bolster parasitoid conservation in reseeded grassland habitats., (Published by Oxford University Press on behalf of Entomological Society of America 2024.)

The orange wheat blossom midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), is a significant wheat pest in the Prairie Provinces of Canada and northern regions of the USA. Wheat phenology plays a critical role in wheat midge oviposition. We hypothesized that S. mosellana oviposition behaviour is influenced by volatile organic compounds (VOCs) emitted by wheat at two adjacent wheat growth stages: preanthesis and postanthesis. A higher number of S. mosellana eggs laid on preanthesis than postanthesis spikes in an oviposition choice experiment using the susceptible spring wheat cultivar 'Roblin'. In preanthesis, wheat emitted higher amounts of Z-3-hexenyl acetate (Z3-06:OAc) than at the postanthesis stage. Higher amounts of methyl ketones such as 2-tridecanone, 2-pentadecanone, and 2-undecanone were emitted by wheat in the postanthesis stage and these VOCs were sensitive to S. mosellana antennae used in the Gas Chromatography-Electroantennographic Detection. Females were attracted to synthetic Z3-06:OAc but were deterred by 2-tridecanone relative to the solvent control in the vertical Y-tube olfactometer. 2-Undecanone and 2-pentadecanone did not show any attractiveness or deterrence. In a no-choice oviposition experiment, fewer eggs were laid in preanthesis wheat exposed to a synthetic VOC blend of Z3-06:OAc, 2-undecanone, 2-tridecanone, and 2-pentadecanone at the concentrations released by postanthesis spikes. This study shows that the reduction of Z3-06:OAc, in the VOC mix, and possibly the increase in 2-tridecanone, are likely responsible for the reduction in oviposition on postanthesis wheat. These results elucidate for the first time the role of specific VOCs mediating S. mosellana oviposition in preanthesis and postanthesis wheat., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Aphids are insect pests that suck phloem sap and introduce salivary proteins into plant tissues through saliva secretion. The effector of salivary proteins plays a key role in the modulation of host plant defense responses and enhancing aphid host adaptation. Based on previous transcriptome sequencing results, a candidate effector cyclin-dependent kinase-like (CDK) was identified from the grain aphid Sitobion avenae . In this study, the function of SaCDK in wheat defense response and the adaptation of S. avenae was investigated. Our results showed that the transient overexpression of SaCDK in tobacco Nicotiana benthamiana suppressed cell death triggered by mouse pro-apoptotic protein-BAX or Phytophthora infestans PAMP-INF1. SaCDK, delivered into wheat cells through a Pseudomonas fluorescens -mediated bacterial type III secretion system, suppressed callose deposition in wheat seedlings, and the overexpression of SaCDK in wheat significantly decreased the expression levels of salicylic acid and jasmonic acid signaling pathway-related genes phenylalanine ammonia lyase ( PAL ), pathogenesis-related 1 protein ( PR1 ), lipoxygenase ( LOX ) and Ω-3 fatty acid desaturase ( FAD ). In addition, aphid bioassay results showed that the survival and fecundity of S. avenae were significantly increased while feeding on the wheat plants carrying SaCDK. Taken together, our findings demonstrate that the salivary protein SaCDK is involved in inhibiting host defense response and improving its host adaptation, which lays the foundation to uncover the mechanism of the interaction of cereal aphids and host plants.

Root-lesion nematode (RLN; Pratylenchus neglectus ) is a migratory endoparasite and a major soilborne pathogen that affects wheat ( Triticum spp.) production worldwide. Genetic resistance is one of the most economical and effective ways to manage P. neglectus in wheat. This study evaluated 37 local cultivars and germplasm lines in seven greenhouse experiments, including 26 hexaploid wheat, six durum wheat, two synthetic hexaploid wheat, one emmer wheat, and two triticale for P. neglectus resistance from 2016 to 2020. North Dakota field soils infested with two RLN populations (350 to 1,125 nematodes per kilogram of soil) were used for resistance screening under controlled greenhouse conditions. The final nematode population density for each cultivar and line was counted under the microscope to categorize the resistance ranking of these entries as resistant, moderately resistant, moderately susceptible, and susceptible. Out of the 37 cultivars and lines, one was classified as resistant (Brennan); 18 were moderately resistant (Divide, Carpio, Prosper, Advance, Alkabo, SY Soren, Barlow, Bolles, Select, Faller, Briggs, WB Mayville, SY Ingmar, W7984, PI 626573, Ben, Grandin, and Villax St. Jose); 11 were moderately susceptible; and seven were susceptible to P. neglectus . The resistant to moderately resistant lines identified in this study could be used in breeding programs after the resistance genes or loci are further elucidated. This research provides valuable information about P. neglectus resistance among wheat and triticale cultivars used in the Upper Midwest region of the United States., Competing Interests: The author(s) declare no conflict of interest.

Background: In hexaploid wheat, quantitative trait loci (QTL) and meta-QTL (MQTL) analyses were conducted to identify genomic regions controlling resistance to cereal cyst nematode (CCN), Heterodera avenae. A mapping population comprising 149 RILs derived from the cross HUW 468 × C 306 was used for composite interval mapping (CIM) and inclusive composite interval mapping (ICIM)., Results: Eight main effect QTLs on three chromosomes (1B, 2A and 3A) were identified using two repeat experiments. One of these QTLs was co-localized with a previously reported wheat gene Cre5 for resistance to CCN. Seven important digenic epistatic interactions (PVE = 5% or more) were also identified, each involving one main effect QTL and another novel E-QTL. Using QTLs earlier reported in literature, two meta-QTLs were also identified, which were also used for identification of 57 candidate genes (CGs). Out of these, 29 CGs have high expression in roots and encoded the following proteins having a role in resistance to plant parasitic nematodes (PPNs): (i) NB-ARC,P-loop containing NTP hydrolase, (ii) Protein Kinase, (iii) serine-threonine/tyrosine-PK, (iv) protein with leucine-rich repeat, (v) virus X resistance protein-like, (vi) zinc finger protein, (vii) RING/FYVE/PHD-type, (viii) glycosyl transferase, family 8 (GT8), (ix) rubisco protein with small subunit domain, (x) protein with SANT/Myb domain and (xi) a protein with a homeobox., Conclusion: Identification and selection of resistance loci with additive and epistatic effect along with two MQTL and associated CGs, identified in the present study may prove useful for understanding the molecular basis of resistance against H. avenae in wheat and for marker-assisted selection (MAS) for breeding CCN resistant wheat cultivars., (© 2023. The Author(s).)

Root lesion nematodes (RLN) of the genus Pratylenchus are causing significant damage in cereal production worldwide. Due to climate change and without efficient and environment-friendly treatments, the damages through RLNs are predicted to increase. Microscopic assessments of RLNs in the field and the greenhouses are time-consuming and laborious. As a result, cereal breeders have mostly ignored this pest. We present a method measuring RLN in infected cereal roots using a standardized PCR approach. Publicly available Pratylenchus neglectus primer combinations were evaluated. An optimal primer combination for RT-qPCR assay was identified to detect and quantify P. neglectus within infected cereal roots. Using the RT-qPCR detection assay, P. neglectus could be clearly distinguished from other plant parasitic nematodes. We could identify P. neglectus DNA in barley and wheat roots as low as 0.863 and 0.916 ng/µl of total DNA, respectively. A single P. neglectus individual was detected in water suspension and within barley and wheat roots. The RT-qPCR detection assay provides a robust and accurate alternative to microscopic nematode identification and quantification. It could be of interest for resistance breeding, where large populations must be screened to detect and quantify P. neglectus in farmer's fields., (© 2023. Springer Nature Limited.)

The resistance to cereal cyst nematode (Heterodera avenae Woll.) in wheat (Triticum aestivum L.) was studied using 114 doubled haploid lines from a novel ITMI mapping population. These lines were screened for nematode infestation in a controlled environment for two years. QTL-mapping analyses were performed across two years (Y1 and Y2) as well as combining two years (CY) data. On the 114 lines that were screened, a total of 2,736 data points (genotype, batch or years, and replication combinations) were acquired. For QTL analysis, 12,093 markers (11,678 SNPs and 415 SSRs markers) were used, after filtering the genotypic data, for the QTL mapping. Composite interval mapping, using Haley-Knott regression (hk) method in R/QTL, was used for QTL analysis. In total, 19 QTLs were detected out of which 13 were novel and six were found to be colocalized or nearby to previously reported Cre genes, QTLs or MTAs for H. avenae or H. filipjevi. Nine QTLs were detected across all three groups (Y1, Y2 and CY) including a significant QTL "QCcn.ha-2D" on chromosome 2D that explains 23% of the variance. This QTL colocalized with a previously identified Cre3 locus. Novel QTL, QCcn.ha-2A, detected in the present study could be the possible unreported homeoloci to QCcn.ha-2D, QCcn.ha-2B.1 and QCcn.ha-2B.2. Six significant digenic epistatic interactions were also observed. In addition, 26 candidate genes were also identified including genes known for their involvement in PPNs (plant parasitic nematodes) resistance in different plant species. In-silico expression of putative candidate genes showed differential expression in roots during specific developmental stages. Results obtained in the present study are useful for wheat breeding to generate resistant genetic resources against H. avenae., (© 2022. The Author(s).)

We evaluated the relative population growth of two stored-product insect species in the genus Trogoderma, the khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae), and the warehouse beetle, Trogoderma variabile Ballion (Coleoptera: Dermestidae). Ten adults of each species were placed in vials containing wheat or paddy rice. These tests were performed at 27 and 32°C and the number of adults in the vials were counted after 35 and 70 days. For all the time intervals and temperatures of both species on wheat, the resulting larval abundances were similar, with the exception of 27°C at 70 days where more T. variabile larvae developed. At the higher temperature, both species had similar population growth on rice. However, the success was mixed at 27°C with T. granarium having a greater abundance after 35 days, while T. variabile dominated after 70 days. Frass production in both commodities was usually similar for the two species, but greater frass production occurred by T. variabile on wheat after 70 days at 27°C, while T. granarium produced more frass on rice after 35 days at 32°C. Both species nearly always caused equivalent commodity damage. Our research suggests that under ideal conditions these two closely, but very differently treated species in commerce from the genus Trogoderma have comparable population growth, and cause similar damage on wheat and rice., (© The Author(s) 2021. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Alterations in the frequency and intensity of drought events are expected due to climate change and might have consequences for plant metabolism and the development of plant antagonists. In this study, the responses of spring wheat (Triticum aestivum) and one of its major pests, the aphid Sitobion avenae, to different drought regimes were investigated, considering different time points and plant parts. Plants were kept well-watered or subjected to either continuous or pulsed drought. Phloem exudates were collected twice from leaves and once from ears during the growth period and concentrations of amino acids, organic acids and sugars were determined. Population growth and survival of the aphid S. avenae were monitored on these plant parts. Relative concentrations of metabolites in the phloem exudates varied with the time point, the plant part as well as the irrigation regime. Pronounced increases in relative concentrations were found for proline, especially in pulsed drought-stressed plants. Moreover, relative concentrations of sucrose were lower in phloem exudates of ears than in those of leaves. The population growth and survival of aphids were decreased on plants subjected to drought and populations grew twice as large on ears compared to leaves. Our study revealed that changes in irrigation frequency and intensity modulate plant-aphid interactions. These effects may at least partly be mediated by changes in the metabolic composition of the phloem sap., Competing Interests: The authors have declared that no competing interests exist.

Background: Tribolium castaneum (Herbst) is one of the most important secondary storage pests of all types of flour and flour-based products. The present study focuses on the fragment producing behaviour of T. castaneum in wheat flour during storage and its effect on the quality parameters and defect action level (DAL) of fragments. The US Food and Drug Administration has set a DAL of 75 insect fragments in 50 g of flour. Box-Behnken design was used to optimize the storage conditions (storage period in days and temperature in degrees Celsius) and insect density (numbers) to keep insect fragments below the DAL., Results: Optimization results indicated that the presence of single number of adult of T. castaneum is enough to cross the DAL of insect fragments within a storage period of 21 days at a storage temperature of 30 °C. Insect fragments cause perceptible changes in the quality of wheat flour. When sample attained DAL of T. castaneum fragments in wheat flour,the various quality parameters were analysed in that moisture content of wheat flour was 10.8 ± 0.26%, total colour change was 2.052 (ΔE value), T. castaneum progeny emergence was 19.66 ± 1, uric acid was 1.8 ± 0.16 g kg -1 and microbial count was 7.34 ± 0.5 cfu g -1 ., Conclusions: Results from the present study indicate that the presence of even a single adult of stored pest in wheat flour should not be ignored. It is mandatory to determine the threshold level and frequent sampling is required to achieve zero tolerance of stored product insects in food commodities. © 2021 Society of Chemical Industry., (© 2021 Society of Chemical Industry.)

Food insecurity and malnutrition have reached critical levels with increased human population, climate fluctuations, water shortage; therefore, higher-yielding crops are in the spotlight of numerous studies. Abiotic factors affect the yield of staple food crops; among all, wheat stem sawfly ( Cephus cinctus Norton) and orange wheat blossom midge ( Sitodiplosis mosellana ) are two of the most economically and agronomically harmful insect pests which cause yield loss in cereals, especially in wheat in North America. There is no effective strategy for suppressing this pest damage yet, and only the plants with intrinsic tolerance mechanisms such as solid stem phenotypes for WSS and antixenosis and/or antibiosis mechanisms for OWBM can limit damage. A major QTL and a causal gene for WSS resistance were previously identified in wheat, and 3 major QTLs and a causal gene for OWBM resistance. Here, we present a comparative analysis of coding and non-coding features of these loci of wheat across important cereal crops, barley, rye, oat, and rice. This research paves the way for our cloning and editing of additional WSS and OWBM tolerance gene(s), proteins, and metabolites.

Salicylic acid (SA), a phytohormone, has been considered to be a key regulator mediating plant defence against pathogens. It is still vague how SA activates plant defence against herbivores such as chewing and sucking pests. Here, we used an aphid-susceptible wheat variety to investigate Sitobion avenae response to SA-induced wheat plants, and the effects of exogenous SA on some defence enzymes and phenolics in the plant immune system. In SA-treated wheat seedlings, intrinsic rate of natural increase (rm), fecundity and apterous rate of S. avenae were 0.25, 31.4 nymphs/female and 64.4%, respectively, and significantly lower than that in the controls (P < 0.05). Moreover, the increased activities of phenylalanine-ammonia-lyase, polyphenol oxidase (PPO) and peroxidase in the SA-induced seedlings obviously depended on the sampling time, whereas activities of catalase and 4-coumarate:CoA ligase were suppressed significantly at 24, 48 and 72 h in comparison with the control. Dynamic levels of p-coumaric acid at 96 h, caffeic acid at 24 and 72 h and chlorogenic acid at 24, 48 and 96 h in wheat plants were significantly upregulated by exogenous SA application. Nevertheless, only caffeic acid content was positively correlated with PPO activity in SA-treated wheat seedlings (P = 0.031). These findings indicate that exogenous SA significantly enhanced the defence of aphid-susceptible wheat variety against aphids by regulating the plant immune system, and may prove a potential application of SA in aphid control.

This study was carried out to investigate the efficacy of the non-thermal atmospheric pressure plasma produced with dielectric barrier discharge (APPD) using air as a processing gas and microwave energy to control Tribolium castaneum and Trogoderma granarium adults and larvae in wheat grains. Insects' mortality was found to be power and time-dependent. The results indicated that non-thermal APPD and the microwave have enough insecticidal effect on the target pests. From the bioassay, LT50's and LT90's levels were estimated, T. granarium larvae appeared more tolerant to non-thermal APPD and the microwave energy than adults 7 days post-exposure. The germination percentage of wheat grains increased as the time of exposure to the non-thermal APPD increased. On the contrary, the germination percentage of wheat grains decreased as the time of exposure to the microwave increased. In addition, changes in antioxidant enzyme activities, catalase (CAT), glutathione S-transferase (GST) and peroxidase, in adults and larvae were examined after 24 h post-treatment to non-thermal APPD at 15.9 W power level, which caused 50% mortality. The activity of CAT, GST and lipid peroxide in the treated larvae showed a significant increase post-exposure to the non-thermal APPD at 15.9 W power level. On the other hand, no significant change in GSH-Px activity was observed. Reductions in the level of glutathione (GSH) and protein content occurred in treated larvae in comparison with the control.

The pathogen cereal cyst nematode (CCN) is deleterious to Triticeae crops and is a threat to the global crop yield. Accession no. 1 of Aegilops variabilis, a relative of Triticum aestivum (bread wheat), is highly resistant to CCN. Our previous study demonstrated that the expression of the phenylalanine ammonia lyase (PAL) gene AevPAL1 in Ae. variabilis is strongly induced by CCN. PAL, the first enzyme of phenylpropanoid metabolism, is involved in abiotic and biotic stress responses. However, its role in plant-CCN interaction remains unknown. In the present study, we proved that AevPAL1 helps to confer CCN resistance through affecting the synthesis of salicylic acid (SA) and downstream secondary metabolites. The silencing of AevPAL1 increased the incidence of CCN infection in roots and decreased the accumulation of SA and phenylalanine (Phe)-derived specialized metabolites. The exogenous pre-application of SA also improved CCN resistance. Additionally, the functions of PAL in phenylpropanoid metabolism correlated with tryptophan decarboxylase (TDC) functioning in tryptophan metabolism pathways. The silencing of either AevPAL1 or AevTDC1 exhibited a concomitant reduction in the expression of both genes and the contents of metabolites downstream of PAL and TDC. These results suggested that AevPAL1, possibly in coordination with AevTDC1, positively contributes to CCN resistance by altering the downstream secondary metabolites and SA content in Ae. variabilis. Moreover, AevPAL1 overexpression significantly enhanced CCN resistance in bread wheat and did not exhibit significant negative effects on yield-related traits, suggesting that AevPAL1 is valuable for the genetic improvement of CCN resistance in bread wheat., (© 2021 Society for Experimental Biology and John Wiley & Sons Ltd.)

Wheat is an economically, socially, and nutritionally important crop, however, aphid infestation can often reduce wheat yield through feeding and virus transmission. Through field phenotyping, we investigated aphid resistance in ancestral wheat Triticum monococcum (L.). Aphid (Rhopalosiphum padi (L.), Sitobion avenae (F.) and Metopolophium dirhodum (Wlk.)) populations and natural enemy presence (parasitised mummified aphids, ladybird adults and larvae and lacewing eggs and larvae) on two naturally susceptible wheat varieties, Triticum aestivum (L.) var. Solstice and T. monococcum MDR037, and three potentially resistant genotypes T. monococcum MDR657, MDR045 and MDR049 were monitored across three years of field trials. Triticum monococcum MDR045 and MDR049 had smaller aphid populations, whereas MDR657 showed no resistance. Overall, natural enemy presence was positively correlated with aphid populations; however, MDR049 had similar natural enemy presence to MDR037 which is susceptible to aphid infestation. It is hypothesised that alongside reducing aphid population growth, MDR049 also confers indirect resistance by attracting natural enemies. The observed resistance to aphids in MDR045 and MDR049 has strong potential for introgression into commercial wheat varieties, which could have an important role in Integrated Pest Management strategies to reduce aphid populations and virus transmission.

Interactions between plants and herbivores are key drivers of evolution and ecosystem complexity. We investigated the role of plant labile carbohydrates and nitrogen on wheat-aphid relations in a 2 2 factorial combining [CO 2 ] and nitrogen supply. We measured life history traits (assay 1) and feeding behaviour (assay 2) of bird-cherry oat aphid (Rhopalosiphum padi L.) and English grain aphid (Sitobion avenae F.) forced to feed on single leaf laminae, and reproduction of R. padi in a setting where insects moved freely along the plant (assay 3). Experimental setting impacted aphid traits. Where aphids were constrained to single leaf, high nitrogen reduced their fitness and discouraged phloem feeding. Where aphids could move throughout the plant, high nitrogen enhanced their reproduction. Aphid responses to the interaction between nitrogen and [CO 2 ] varied with experimental setting. The number of R. padi adults varied tenfold with plant growing conditions and correlated negatively with molar concentration of sugars in stem (assay 3). This finding has two implications. First, the common interpretation that high nitrogen favours insect fitness because protein-rich animal bodies have to build from nitrogen-poor plant food needs expanding to account for the conspicuous association between low nitrogen and high concentration of labile carbohydrates in plant, which can cause osmotic stress in aphids. Second, the function of labile carbohydrates buffering grain growth needs expanding to account for the osmotic role of carbohydrates in plant resistance to aphids.

There are two major categories of observation data in studying time-dependent processes: one is the time-series data, and the other is the perhaps lesser-recognized but similarly prevalent time-to-event data (also known as survival or failure time). Examples in entomology include molting times and death times of insects, waiting times of predators before the next attack or the hiding times of preys. A particular challenge in analyzing time-to-event data is the observation censoring, or the incomplete observation of survival times, dealing which is a unique advantage of survival analysis statistics. Even with a perfectly designed experiment being conducted perfectly, such 'naturally' censoring may still be unavoidable due to the natural processes, including the premature death in the observation of insect development, the variability in instarship, or simply the continuous nature of time process and the discrete nature of sampling intervals. Here we propose to apply the classic Cox proportional hazards model for modeling both insect development and survival rates (probabilities) with a unified survival analysis approach. We demonstrated the advantages of the proposed approach with the development and survival datasets of 1800 Russian wheat aphids from their births to deaths, observed under 25 laboratory treatments of temperatures and plant growth stages.

Key Message: Cmc4, a wheat curl mite resistance gene, was delimited to a 523 kb region and a diagnostic marker haplotype was identified for selecting Cmc4 in breeding programs. Wheat curl mite (WCM, Aceria tosichella Keifer) is a disastrous wheat pest in many wheat-growing regions worldwide. WCM not only directly affects wheat yield, but also transmits wheat streak mosaic virus. Growing WCM resistant cultivars is the most economical and sustainable method to reduce its damage. A hard winter wheat breeding line OK05312 (PI 670019) carries Cmc4 gene resistance to A. tosichella and has many desirable agronomic traits. To finely map Cmc4 in OK05312, two recombinant inbred line populations were developed from crosses between OK05312 and two susceptible cultivars, SD06165 and Jerry, genotyped using single nucleotide polymorphism (SNP) markers generated from genotyping-by-sequencing (GBS), and phenotyped for WCM resistance. Gene mapping using the two SNP maps confirmed Cmc4 in OK05312 that explained up to 68% of the phenotypic variation. Further analysis delimited Cmc4 to a ~ 523 kb region between SNPs SDOKSNP6314 and SDOKSNP2805 based on the Ae. tauschii reference genome. We developed 18 polymorphic Kompetitive Allele Specific PCR (KASP) markers using the sequences of GBS-SNPs in this region and 23 additional KASP markers based on the SNPs between the parents derived from 90K SNP chips. The KASP markers SDOKSNP6314 and SDOKSNP9699 are closest to Cmc4 and can be used to diagnose the presence of Cmc4 in wheat breeding programs. Haplotype analysis suggested that Cmc TAM112 in TAM112 might be the same gene as Cmc4.

Most insecticides commonly used in storage facilities are synthetic, an issue that generates concerns about food safety and public health. Therefore, the development of eco-friendly pest management tools is urgently needed. In the present study, a 6% ( w/w ) Hazomalania voyronii essential oil-based nanoemulsion (HvNE) was developed and evaluated for managing Tribolium confusum , T. castaneum , and Tenebrio molitor , as an eco-friendly wheat protectant. Larval and adult mortality was evaluated after 4, 8, and 16 h, and 1, 2, 3, 4, 5, 6, and 7 days, testing two HvNE concentrations (500 ppm and 1000 ppm). T. confusum and T. castaneum adults and T. molitor larvae were tolerant to both concentrations of the HvNE, reaching 13.0%, 18.7%, and 10.3% mortality, respectively, at 1000 ppm after 7 days of exposure. However, testing HvNE at 1000 ppm, the mortality of T. confusum and T. castaneum larvae and T. molitor adults 7 days post-exposure reached 92.1%, 97.4%, and 100.0%, respectively. Overall, the HvNE can be considered as an effective adulticide or larvicide, depending on the target species. Our results highlight the potential of H . voyronii essential oil for developing green nanoinsecticides to be used in real-world conditions against key stored-product pests.

(1) Background: The wheat curl mite ( Aceria tosichella Keifer) is a key pest of wheat ( Triticum aestivum L.) worldwide. While a number of wheat cultivars resistant to the mites have been employed to minimize the impact on the yield and quality of grain, little is known regarding the mechanisms underlying host plant resistance. Therefore, the goal of this study was to explore changes in transcriptome of resistant and susceptible wheat in order to quantify the molecular changes that drive host plant resistance. (2) Methods: Two varieties, wheat curl mite-susceptible (Karl 92) and wheat curl mite-resistant (TAM112) wheat, both at 2-week postemergence, were used in this study. Half of the plants were exposed to wheat curl mite herbivory and half remained mite-free and served as controls. Transcriptome changes were quantified using RNA-seq and compared among treatments to identify genes and pathways affected by herbivores. (3) Results: We identified a number of genes and pathways involved in plant defenses against pathogens, herbivores, and abiotic stress that were differentially expressed in the resistant wheat exposed to wheat curl mite herbivory but were unaffected in the susceptible wheat. (4) Conclusions: Our outcomes indicated that resistant wheat counteracts wheat curl mite exposure through effective induction of genes and pathways that enhance its defense responses.

The Hessian fly Mayetiola destructor (Diptera: Cecidmyiidae) is a major pest of wheat, globally. We conducted a series of laboratory choice and no-choice assays to quantify Hessian fly host preference for barley (cv. Champion), oat (cv. Cayuse), susceptible (cv. Alturas), and resistant (cv. Hollis) wheat. In addition, larval survivorship and adult emergence were compared among the evaluated host plants. We then examined whether insect preference for a host can be explained by differences in plant spectral reflectance. Further, larval survivorship and adult emergence were compared among host plants in relation to phytohormone concentrations. Hessian flies laid more eggs on wheat compared to either oat or barley. Spectral reflectance measurements of leaves were similar between susceptible and resistant wheat cultivars but different from those of barley and oat. Our results suggested that higher reflectance in the near-infrared range and lower reflectance in the visible range may be used by females for host selection. Hessian fly larvae were unable to develop into the pupal stage on resistant wheat and oat. No significant difference in larval survivorship was detected between the susceptible wheat and barley. However, adult emergence was significantly higher on barley than the susceptible wheat. Phytohormonal evaluations revealed that salicylic acid (SA) may be an important contributor to plant defense response to larval feeding as relatively higher concentrations of SA were present in oat and resistant wheat. While resistance in the resistant wheat is achieved only through antibiosis, both antibiosis and antixenosis were in effect rendering oat as a non-host for Hessian flies.

Root lesion nematode (RLN; Pratylenchus thornei) causes extensive yield losses in wheat worldwide and thus pose serious threat to global food security. Reliance on fumigants (such as methyl bromide) and nematicides for crop protection has been discouraged due to environmental concerns. Hence, alternative environment friendly control measures like finding and deployment of resistance genes against Pratylenchus thornei are of significant importance. In the present study, genome-wide association study (GWAS) was performed using single-locus and multi-locus methods. In total, 143 wheat genotypes collected from pan-Indian wheat cultivation states were used for nematode screening. Genotypic data consisted of  > 7K SNPs with known genetic positions on the high-density consensus map was used for association analysis. Principal component analysis indicated the existence of sub-populations with no major structuring of populations due to the origin. Altogether, 25 significant marker trait associations were detected with - log10 (p value) > 4.0. Three large linkage disequilibrium blocks and the corresponding haplotypes were found to be associated with significant SNPs. In total, 37 candidate genes with nine genes having a putative role in disease resistance (F-box-like domain superfamily, Leucine-rich repeat, cysteine-containing subtype, Cytochrome P450 superfamily, Zinc finger C2H2-type, RING/FYVE/PHD-type, etc.) were identified. Genomic selection was conducted to investigate how well one could predict the phenotype of the nematode count without performing the screening experiments. Prediction value of r = 0.40 to 0.44 was observed when 56 to 70% of the population was used as a training set. This is the first report where GWAS has been conducted to find resistance against root lesion nematode (P. thornei) in Indian wheat germplasm.

Yield losses because of cereal cyst nematodes could be as high as 92%, causing a bottleneck for wheat production. An integrated approach (application of pesticides, crop rotation, and use of host resistance) is needed to manage this devastating pathogen where resistant cultivars are considered most effective. This necessitates the identification of nematode-resistant sources in the available germplasm. Here, we report on the genetic mapping of nematode resistance in 255 diverse prebreeding lines (PBLs) employing an association mapping strategy. Altogether, seven additive quantitative trait loci (QTL) were identified on chromosomes 1A, 2A, 2B, 2D, 3A, 6B, and 6D explaining a maximum of 9.42% phenotypic variation where at least five QTL (on chromosomes 2A, 2B, 2D, 6B, and 6D) are located on the same chromosomes that harbor the already known nematode resistance genes. Resistant PBLs carried Aegilops squarrosa (436) in their pedigree which could be the possible source of positive alleles. To add to it, better yield performance of the identified nematode-resistant lines under stress conditions indicates that the germplasm can provide both nematode resistance and high-yielding cultivars.

Key Message: Resistance conferred by the Cre8 locus of wheat prevents cereal cyst nematode feeding sites from reaching and invading root metaxylem vessels. Cyst nematodes develop syncytial feeding sites within plant roots. The success of these sites is affected by host plant resistance. In wheat (Triticum aestivum L.), 'Cre' loci affect resistance against the cereal cyst nematode (CCN) Heterodera avenae. To investigate how one of these loci (Cre8, on chromosome 6B) confers resistance, CCN-infected root tissue from susceptible (-Cre8) and resistant (+Cre8) wheat plants was examined using confocal microscopy and laser ablation tomography. Confocal analysis of transverse sections showed that feeding sites in the roots of -Cre8 plants were always adjacent to metaxylem vessels, contained many intricate 'web-like' cell walls, and sometimes 'invaded' metaxylem vessels. In contrast, feeding sites in the roots of +Cre8 plants were usually not directly adjacent to metaxylem vessels, had few inner cell walls and did not 'invade' metaxylem vessels. Models based on data from laser ablation tomography confirmed these observations. Confocal analysis of longitudinal sections revealed that CCN-induced xylem modification that had previously been reported for susceptible (-Cre8) wheat plants is less extreme in resistant (+Cre8) plants. Application of a lignin-specific stain revealed that secondary thickening around xylem vessels in CCN-infected roots was greater in +Cre8 plants than in -Cre8 plants. Collectively, these results indicate that Cre8 resistance in wheat acts by preventing cyst nematode feeding sites from reaching and invading root metaxylem vessels.

Key Message: A major QTL for oviposition deterrence to orange wheat blossom midge was detected on chromosome 1A in the Canadian breeding line BW278 that was inherited from the Chinese variety Sumai-3. Orange wheat blossom midge (OWBM, Sitodiplosis mosellana Géhin, Diptera: Cecidomyiidae) is an important insect pest of wheat (Triticum aestivum L.) that reduces both grain yield and quality. Oviposition deterrence results in a reduction of eggs deposited on spikes relative to that observed on a wheat line preferred by OWBM. Quantification of oviposition deterrence is labor-intensive, so wheat breeders require efficient DNA markers for the selection of this trait. The objective of this study was to identify quantitative trait loci (QTL) for oviposition deterrence in a doubled haploid (DH) population developed from the spring wheat cross Superb/BW278. The DH population and check varieties were evaluated for OWBM kernel damage from five field nurseries over three growing seasons. QTL analysis identified major effect loci on chromosomes 1A (QSm.mrc-1A) and 5A (QSm.mrc-5A). Reduced kernel damage was contributed by BW278 at QSm.mrc-1A and Superb at QSm.mrc-5A. QSm.mrc-1A mapped to the approximate location of the oviposition deterrence QTL previously found in the American variety Reeder. However, haplotype analysis revealed that BW278 inherited this oviposition deterrence allele from the Chinese spring wheat variety Sumai-3. QSm.mrc-5A mapped to the location of awn inhibitor gene B1, suggesting that awns hinder OWBM oviposition. Single-nucleotide polymorphisms (SNPs) were identified for predicting the presence or absence of QSm.mrc-1A based upon haplotype. Functional annotation of candidate genes in 1A QTL intervals revealed eleven potential candidate genes, including a gene involved in terpenoid biosynthesis. SNPs for QSm.mrc-1A and fully awned spikes provide a basis for the selection of oviposition deterrence to OWBM.

The Hessian fly is an obligate parasite of wheat causing significant economic damage, and triggers either a resistant or susceptible reaction. However, the molecular mechanisms of susceptibility leading to the establishment of the larvae are unknown. Larval survival on the plant requires the establishment of a steady source of readily available nutrition. Unlike other insect pests, the Hessian fly larvae have minute mandibles and cannot derive their nutrition by chewing tissue or sucking phloem sap. Here, we show that the virulent larvae produce the glycoside hydrolase MdesGH32 extra-orally, that localizes within the leaf tissue being fed upon. MdesGH32 has strong inulinase and invertase activity aiding in the breakdown of the plant cell wall inulin polymer into monomers and converting sucrose, the primary transport sugar in plants, to glucose and fructose, resulting in the formation of a nutrient-rich tissue. Our finding elucidates the molecular mechanism of nutrient sink formation and establishment of susceptibility.

Three new sesquiterpenoids, peniterpenoids A - C (1-3), together with six known metabolites (4-9) were isolated from an entomogenous fungus Penicillium janthinellum (LB1.20090001) collected from a wheat cyst nematode. The structures of the new compounds were elucidated based on NMR and HRESIMS spectroscopic analyses. The absolute configuration of the C-8 secondary alcohol of peniterpenoid B (2) was determined by [Rh 2 (OCOCF 3 ) 4 ]-induced ECD experiment. Subsequently, the antimicrobial and DPPH scavenging activities were determined. Compounds 6-8 exhibited moderate antibacterial activities against Staphylococcus aureus (CGMCC1.2465) with MIC values of 25.0, 50.0 and 12.5 μg/mL, respectively., (Copyright © 2020. Published by Elsevier B.V.)

Russian wheat aphid (RWA; Diuraphis noxia Kurdjumov) resistance on the 1D chromosome of wheat has been the subject of intensive research. Conversely, the deployment of the Dn4 derived RWA resistant varieties diminished in recent years due to the overcoming of the resistance it imparts in the United States of America. However, this resistance has not been deployed in South Africa despite reports that Dn4 containing genotypes exhibited varying levels of resistance against the South African RWA biotypes. It is possible that there may be certain genetic differences within breeding lines or cultivars that influence the expression of resistance. The aim of this study was to identify single nucleotide polymorphism (SNP) markers associated with resistance to South African RWA biotypes. A panel of thirty-two wheat lines were phenotyped for RWA resistance using four South African RWA biotypes and a total of 181 samples were genotyped using the Illumina 9K SNP wheat chip. A genome wide association study using 7598 polymorphic SNPs showed that the population was clustered into two distinct subpopulations. Twenty-seven marker trait associations (MTA) were identified with an average linkage disequilibrium of 0.38 at 10 Mbp. Four of these markers were highly significant and three correlated with previously reported quantitative trait loci linked to RWA resistance in wheat. Twenty putative genes were annotated using the IWGSC RefSeq, three of which are linked to plant defence responses. This study identified novel chromosomal regions that contribute to RWA resistance and contributes to unravelling the complex genetics that control RWA resistance in wheat., Competing Interests: Scott L. Sydenham is presently an employee of LongReach Plant Breeders Management Pty Ltd. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

The cereal cyst nematode, Heterodera avenae is distributed worldwide and causes substantial damage in bread wheat, Triticum aestivum. This nematode is extremely difficult to manage because of its prolonged persistence as unhatched eggs encased in cysts. Due to its sustainable and target-specific nature, RNA interference (RNAi)-based strategy has gained unprecedented importance for pest control. To date, RNAi strategy has not been exploited to manage H. avenae in wheat. In the present study, 40 H. avenae target genes with different molecular function were rationally selected for in vitro soaking analysis in order to assess their susceptibility to RNAi. In contrast to target-specific downregulation of 18 genes, 7 genes were upregulated and 15 genes showed unaltered expression (although combinatorial soaking showed some of these genes are RNAi susceptible), suggesting that a few of the target genes were refractory or recalcitrant to RNAi. However, RNAi of 37 of these genes negatively altered nematode behavior in terms of reduced penetration, development and reproduction in wheat. Subsequently, wheat plants were transformed with seven H. avenae target genes (that showed greatest abrogation of nematode parasitic success) for host-induced gene silencing (HIGS) analysis. Transformed plants were molecularly characterized by PCR, RT-qPCR and Southern hybridization. Production of target gene-specific double- and single-stranded RNA (dsRNA/siRNA) was detected in transformed plants. Transgenic expression of galectin, cathepsin L, vap1, serpin, flp12, RanBPM and chitinase genes conferred 33.24-72.4 % reduction in H. avenae multiplication in T 1 events with single copy ones exhibiting greatest reduction. A similar degree of resistance observed in T 2 plants indicated the consistent HIGS effect in the subsequent generations. Intriguingly, cysts isolated from RNAi plants were of smaller size with translucent cuticle compared to normal size, dark brown control cysts, suggesting H. avenae developmental retardation due to HIGS. Our study reinforces the potential of HIGS to manage nematode problems in crop plant., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Wheat aphids are major wheat sap sucking pests found throughout the world. The analysis of wheat aphid population dynamics to develop aphid control strategies is therefore important. Even if all factors that control the size of aphid populations are known, several mathematical tools are needed to help us understand their combined effect. Based on the knowledge of population ecology and catastrophe theory, we proposed a generalized population dynamics model to describe variation of wheat aphid populations and obtained a dynamic threshold function for aphid control. Field survey data from 1997 to 2002 were used to validate this model. The results indicated the model could predict the results of practical measures against a pest if the factors of their immediate effects are known or could be estimated. By explaining and forecasting the size of an aphid outbreak and its probability of occurrence, this catastrophe model can provide a scientific basis for wheat aphid control., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Odorant binding proteins play a key role in the olfactory system and are involved in the odor perception and discrimination of insects. To investigate the potential physiological functions of SaveOBP9 in Sitobion avenae , fluorescence ligand binding experiments, molecular docking, RNA interference, and behavioral tests were performed. Fluorescence binding assay results showed that SaveOBP9 had broad and high (Ki < 10 μM) binding abilities with most of the wheat volatiles, but was more obvious at pH 7.4 than pH 5.0. The binding sites of SaveOBP9 to the volatiles were predicted well by three-dimensional docking structure modeling and molecular docking. Moreover, S. avenae showed a strong behavioral response with the four compounds of wheat. The reduction in mRNA transcript levels after the RNA interference significantly reduced the expression level of SaveOBP9 and induced the non-significant response of S. avenae to the tetradecane, octanal, decanal, and hexadecane. This study provides evidence that SaveOBP9 might be involved in the chemoreception of wheat volatile organic compounds and can successfully contribute in the integrated management programs of S. avenae .

Russian wheat aphid, Diuraphis noxia (Kurdjumov), is a severe pest of wheat, Triticum aestivum L., throughout the world. Resistant cultivars are viewed as the most economical and environmentally viable control available. Studies to identify molecular markers to facilitate resistance breeding started in the 1990s, and still continue. This paper reviews and discusses the literature pertaining to the D. noxia R-genes on chromosome 7D, and markers reported to be associated with them. Individual plants with known phenotypes from a panel of South African wheat accessions are used as examples. Despite significant inputs from various research groups over many years, diagnostic markers for resistance to D. noxia remain elusive. Factors that may have impeded critical investigation, thus blurring the accumulation of a coherent body of information applicable to Dn resistance, are discussed. This review calls for a more fastidious approach to the interpretation of results, especially considering the growing evidence pointing to the complex regulation of aphid resistance response pathways in plants. Appropriate reflection on prior studies, together with emerging knowledge regarding the complexity and specificity of the D. noxia -wheat resistance interaction, should enable scientists to address the challenges of protecting wheat against this pest in future.

Pantoea agglomerans is a Gram-negative bacterium that is ubiquitous in the environment, colonizing animals, humans, and numerous plants, including cotton and wheat. A lipopolysaccharide-containing fermented wheat flour extract from P. agglomerans (Somacy-FP100) is proposed for use as a food ingredient for individuals seeking foods for healthy aging. Previously published genotoxicity studies with Somacy-FP100 reported its lack of genotoxicity in vitro, but a subchronic toxicity study has not yet been performed. Therefore, to demonstrate the safety of Somacy-FP100 for use as a food ingredient, a 90-day oral (gavage) toxicity study in rats was conducted. Male and female Han Wistar rats were administered vehicle (control) or Somacy-FP100 at 500, 1500, or 4500 mg/kg body weight/day at a dose volume of 10 mL/kg body weight, for at least 90 days. No test article-related adverse clinical signs or effects on body weight, food consumption, or clinical pathology were observed, and there were no macroscopic or microscopic findings related to the test article. Therefore, 4500 mg/kg body weight/day (the highest dose tested and highest feasible dose) was established as the no-observed-adverse-effect level. This absence of subchronic toxicity, in addition to the previously reported lack of genotoxicity, demonstrates the safety of Somacy-FP100 for use as a food ingredient., (© 2020 John Wiley & Sons, Ltd.)

Background: Plant viruses maintain intricate interactions with their vector and non-vector insects and can impact the fitness of insects. However, the details of their molecular and cellular mechanisms have not been studied well. We compared the transcriptome-level responses in vector and non-vector aphids (Schizaphis graminum and Rhopalosiphum padi, respectively) after feeding on wheat plants with viral infections (Barley Yellow Dwarf Virus (BYDV) and Wheat dwarf virus (WDV), respectively). We conducted differentially expressed gene (DEG) annotation analyses and observed DEGs related to immune pathway, growth, development, and reproduction. And we conducted cloning and bioinformatic analyses of the key DEG involved in immune., Results: For all differentially expressed gene analyses, the numbers of DEGs related to immune, growth, development, reproduction and cuticle were higher in vector aphids than in non-vector aphids. STAT5B (signal transducer and activator of transcription 5B), which is involved in the JAK-STAT pathway, was upregulated in R. padi exposed to WDV. The cloning and bioinformatic results indicated that the RpSTAT5B sequence contains a 2082 bp ORF encoding 693 amino acids. The protein molecular weight is 79.1 kD and pI is 8.13. Analysis indicated that RpSTAT5B is a non-transmembrane protein and a non-secreted protein. Homology and evolutionary analysis indicated that RpSTAT5B was closely related to R. maidis., Conclusions: Unigene expression analysis showed that the total number of differentially expressed genes (DEGs) in the vector aphids was higher than that in the non-vector aphids. Functional enrichment analysis showed that the DEGs related to immunity, growth and reproduction in vector aphids were higher than those in non-vector aphids, and the differentially expressed genes related to immune were up-regulated. This study provides a basis for the evaluation of the response mechanisms of vector/non-vector insects to plant viruses.

Key Message: Two new Hessian fly resistance QTLs (H35 and H36) and tightly linked SNP markers were identified in a US hard winter wheat SD06165. Hessian fly (HF), Mayetiola destructor (Say), is one of the most destructive pests in wheat (Triticum aestivum L.) worldwide. Growing resistant cultivars is the most effective approach to minimize Hessian fly damage. To identify new quantitative trait loci (QTLs) for HF resistance, a recombinant inbred line population was developed by crossing HF resistant wheat line SD06165 to a susceptible line OK05312. The population was genotyped with 1709 single-nucleotide polymorphisms (SNPs) generated from genotyping-by-sequencing and phenotyped for HF resistance in greenhouses. Two novel QTLs for HF resistance were identified from SD06165. The major QTL, designated as H35, was closely linked to SNP marker SDOKSNP7679 on chromosome 3BS that explained 23.8% and 36.0% of the phenotypic variations; the minor QTL, designated as H36, was flanked by SNP markers SDOKSNP1618 and SDOKSNP8089 on chromosome 7AS and explained 8.5% and 13.1% of the phenotypic variation in the two experiments. Significant interaction was detected between the two QTLs. Seventeen SNPs that tightly link to H35 and eight SNPs that tightly link to H36 were converted to kompetitive allele specific polymerase chain reaction markers for selecting these QTLs in breeding programs.

Heterodera avenae, as an obligate endoparasite, causes severe yield loss in wheat (Triticum aestivum). Investigation on the mechanisms how H. avenae perceives wheat roots is limited. Here, the attractiveness of root exudates from eight plant genotypes to H. avenae were evaluated on agar plates. Results showed that the attraction of H. avenae to the root exudates from the non-host Brachypodium distachyon variety Bd21-3 was the highest, approximately 50 infective second-stage juveniles (J2s) per plate, followed by that from three H. avenae-susceptible wheat varieties, Zhengmai9023, Yanmai84 and Xiangmai25, as well as the resistant one of Xinyuan958, whereas the lowest attractive activity was observed in the two H. avenae-resistant wheat varieties, Xianmai20 (approximately 12 J2s/plate) and Liangxing66 (approximately 11 J2s/plate). Then Bd21-3, Zhengmai9023 and Heng4399 were selected for further assays as their different attractiveness and resistance to H. avenae, and attractants for H. avenae in their root exudates were characterized to be heat-labile and low-molecular compounds (LM) by behavioral bioassay. Based on these properties of the attractants, a principle of identifying attractants for H. avenae was set up. Then LM of six root exudates from the three plants with and without heating were separated and analyzed by HPLC-MS. Finally, dihydroxyacetone (DHA), methylprednisolone succinate, embelin and diethylpropionin in the root exudates were identified to be putative attractants for H. avenae according to the principle, and the attraction of DHA to H. avenae was validated by behavioral bioassay on agar. Our study enhances the recognition to the orientation mechanism of H. avenae towards wheat roots., Competing Interests: NO authors have competing interests.

Cyst nematodes induce host-plant root cells to form syncytia from which the nematodes feed. Comprehensive histological investigation of these feeding sites is complicated by their variable shape and their positions deep within root tissue. Using tissue clearing and confocal microscopy, we examined thick (up to 150 μm) sections of wheat roots infected by cereal cyst nematodes (Heterodera avenae). This approach provided clear views of feeding sites and surrounding tissues, with resolution sufficient to reveal spatial relationships among nematodes, syncytia and host vascular tissues at the cellular level. Regions of metaxylem vessels near syncytia were found to have deviated from classical developmental patterns. Xylem vessel elements in these regions had failed to elongate but had undergone radial expansion, becoming short and plump rather than long and cylindrical. Further investigation revealed that vessel elements cease to elongate shortly after infection and that they later experience delays in secondary thickening (lignification) of their outer cell walls. Some of these elements were eventually incorporated into syncytial feeding sites. By interfering with a developmental program that normally leads to programmed cell death, H. avenae may permit xylem vessel elements to remain alive for later exploitation by the parasite.

The wheat curl mite, Aceria tosichella Keifer, one of the most destructive arthropod pests of bread wheat worldwide, inflicts significant annual reductions in grain yields. Moreover, A. tosichella is the only vector for several economically important wheat viruses in the Americas, Australia and Europe. To date, mite-resistant wheat genotypes have proven to be one of the most effective methods of controlling the A. tosichella-virus complex. Thus, it is important to elucidate A. tosichella population genetic structure, in order to better predict improved mite and virus management. Two genetically distinct A. tosichella lineages occur as pests of wheat in Australia, Europe, North America, South America and the Middle East. These lineages are known as type 1 and type 2 in Australia and North America and in Europe and South America as MT-8 and MT-1, respectively. Type 1 and type 2 mites in Australia and North America are delineated by internal transcribed spacer 1 region (ITS1) and cytochrome oxidase I region (COI) sequence differences. In North America, two A. tosichella genotypes known as biotypes are recognized by their response to the Cmc3 mite resistance gene in wheat. Aceria tosichella biotype 1 is susceptible to Cmc3 and biotype 2 is virulent to Cmc3. In this study, ITS1 and COI sequence differences in 25 different populations of A. tosichella of known biotype 1 or biotype 2 composition were characterized for ITS1 and COI sequence differences and used to model spatio-temporal dynamics based on biotype prevalence. Results showed that the proportion of biotype 1 and 2 varies both spatially and temporally. Greater ranges of cropland and grassland within 5000m of the sample site, as well as higher mean monthly precipitation during the month prior to sampling appear to reduce the probability of occurrence of biotype 1 and increase the probability of occurrence of biotype 2. The results suggest that spatio-temporal modeling can effectively improve A. tosichella management. Continual integration of additional current and future precipitation and ground cover data into the existing model will further improve the accuracy of predicting the occurrence of A. tosichella in annual wheat crops, allowing producers to make informed decisions about the selection of varieties with different A. tosichella resistance genes., Competing Interests: The authors have declared that no competing interests exist.

Associations formed between plants and arbuscular mycorrhizal (AM) fungi are characterized by the bi-directional exchange of fungal-acquired soil nutrients for plant-fixed organic carbon compounds. Mycorrhizal-acquired nutrient assimilation by plants may be symmetrically linked to carbon (C) transfer from plant to fungus or governed by sink-source dynamics. Abiotic factors, including atmospheric CO 2 concentration ([CO 2 ]), can affect the relative cost of resources traded between mutualists, thereby influencing symbiotic function. Whether biotic factors, such as insect herbivores that represent external sinks for plant C, impact mycorrhizal function remains unstudied. By supplying 33 P to an AM fungus (Rhizophagus irregularis) and 14 CO 2 to wheat, we tested the impact of increasing C sink strength (i.e., aphid herbivory) and increasing C source strength (i.e., elevated [CO 2 ]) on resource exchange between mycorrhizal symbionts. Allocation of plant C to the AM fungus decreased dramatically following exposure to the bird cherry-oat aphid (Rhopalosiphum padi), with high [CO 2 ] failing to alleviate the aphid-induced decline in plant C allocated to the AM fungus. Mycorrhizal-mediated uptake of 33 P by plants was maintained regardless of aphid presence or elevated [CO 2 ], meaning insect herbivory drove asymmetry in carbon for nutrient exchange between symbionts. Here, we provide direct evidence that external biotic C sinks can limit plant C allocation to an AM fungus without hindering mycorrhizal-acquired nutrient uptake. Our findings highlight the context dependency of resource exchange between plants and AM fungi and suggest biotic factors-individually and in combination with abiotic factors-should be considered as powerful regulators of symbiotic function., Competing Interests: Declaration of Interests The authors declare no competing interests., (Crown Copyright © 2020. Published by Elsevier Inc. All rights reserved.)

Cereal cyst nematodes cause serious yield losses of wheat in Hunaghuai winter wheat growing region in China. Beauveria bassiana 08F04 isolated from the surface of cysts is a promising biological control agent for cereal cyst nematodes. As the colonization capacity is a crucial criteria to assess biocontrol effectiveness for a microbial agent candidate, we aimed to label B. bassiana 08F04 for efficient monitoring of colonization in the soil. The binary pCAM-gfp plasmid containing sgfp and hph was integrated into B. bassiana 08F04 using the Agrobacterium tumefaciens-mediated transformation. The transformation caused a significant change in mycelial and conidial yields, and in extracellular chitinase activity in some transformants. The cultural filtrates of some transformants also decreased acetylcholinesterase activity and the survival of Heterodera filipjevi second-stage juveniles relative to the wild-type strain. One transformant (G10) had a growth rate and biocontrol efficacy similar to the wild-type strain, so it was used for a pilot study of B. bassiana colonization conducted over 13 weeks. Real-time PCR results and CFU counts revealed that the population of G10 increased quickly over the first 3 weeks, then decreased slowly over the following 4 weeks before stabilizing. In addition, the application of wild-type B. bassiana 08F04 and transformant G10 significantly reduced the number of H. filipjevi females in roots by 64.4% and 60.2%, respectively. The results of this study have practical applications for ecological, biological and functional studies of B. bassiana 08F04 and for bionematicide registration., Competing Interests: The authors have declared that no competing interests exist.

Background: Schizaphis graminum is one of the most important and devastating cereal aphids worldwide, and its feeding can cause chlorosis and necrosis in wheat. However, little information is available on the wheat defence responses triggered by S. graminum feeding at the molecular level., Results: Here, we collected and analysed transcriptome sequencing data from leaf tissues of wheat infested with S. graminum at 2, 6, 12, 24 and 48 hpi (hours post infestation). A total of 44,835 genes were either up- or downregulated and differed significantly in response to aphid feeding. The expression levels of a number of genes (9761 genes) were significantly altered within 2 hpi and continued to change during the entire 48 h experiment. Gene Ontology analysis showed that the downregulated DEGs were mainly enriched in photosynthesis and light harvesting, and the total chlorophyll content in wheat leaves was also significantly reduced after S. graminum infestation at 24 and 48 hpi. However, a number of related genes of the salicylic acid (SA)-mediated defence signalling pathway and MAPK-WRKY pathway were significantly upregulated at early feeding time points (2 and 6 hpi). In addition, the gene expression and activity of antioxidant enzymes, such as peroxidase and superoxide dismutase, were rapidly increased at 2, 6 and 12 hpi. DAB staining results showed that S. graminum feeding induced hydrogen peroxide (H 2 O 2 ) accumulation at the feeding sites at 2 hpi, and increased H 2 O 2 production was detected with the increases in aphid feeding time. Pretreatment with diphenylene iodonium, an NADPH oxidase inhibitor, repressed the H 2 O 2 accumulation and expression levels of SA-associated defence genes in wheat., Conclusions: Our transcriptomic analysis revealed that defence-related pathways and oxidative stress in wheat were rapidly induced within hours after the initiation of aphid feeding. Additionally, NADPH oxidase plays an important role in aphid-induced defence responses and H 2 O 2 accumulation in wheat. These results provide valuable insight into the dynamic transcriptomic responses of wheat leaves to phytotoxic aphid feeding and the molecular mechanisms of aphid-plant interactions.

The use of chemical pesticides to preserve food commodities is a global issue of concern due to their negative effect on the environment and public health. In recent years, the European Union is trying to reduce their use, favoring alternative or complementary approaches based on natural products. In this scenario, plant-borne essential oils (EOs) represent valid options for Integrated Pest Management (IPM) programs. In the present study, the insecticidal effect of eight EOs obtained from plants from different parts of the world, namely Mentha longifolia, Dysphania ambrosioides, Carlina acaulis, Trachyspermum ammi, Pimpinella anisum, Origanum syriacum, Cannabis sativa and Hazomalania voyronii, were evaluated against two stored-product insect species of economic importance, Prostephanus truncatus and Trogoderma granarium. Simulating a small-scale stored-product conservation environment, an AG-4 airbrush was used to spray maize and wheat with 500 and 1000 ppm of EOs, then T. granarium and P. truncatus were exposed to the stored products and mortality was evaluated over selected time intervals (4, 8, and 16 h, and 1, 2, 3, 4, 5, 6, and 7 days). The EO of C. acaulis exhibited high efficacy against P. truncatus adults at both tested concentrations by killing > 97% of the individuals exposed to treated maize within 3 days at 500 ppm. The EO of D. ambrosioides eliminated all T. granarium adults exposed to 1000 ppm-treated wheat 2 days post-exposure. At this exposure interval, 91.1% of the exposed T. granarium adults died on wheat treated with 1000 ppm of C. acaulis EO. The EO of M. longifolia at both tested concentrations was the most effective against T. granarium larvae, leading to 97.8% mortality at 500 ppm after 3 days of exposure, and 100% mortality at 1000 pm 2 days post-exposure. At 1000 ppm, the EOs of D. ambrosioides and P. anisum led to 95.6 and 90% mortality, respectively, to larvae exposed to treated wheat for 7 days. Overall, our research shed light on the potential of selected EOs, with special reference to M. longifolia, D. ambrosioides, C. acaulis and P. anisum, which could be considered further to develop effective and alternative grain protectants to manage P. truncatus and T. granarium infestations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Silicon (Si) supplementation is well-known for enhancing plant resistance to insect pests, however, only recently studies revealed that Si accumulation in the plant not only confers a mechanical barrier to insect feeding, but also primes jasmonic acid-dependent defenses. Here, we examined whether Si supplementation alters wheat volatile emissions that influence the bird cherry-oat aphid (Rhopalosiphum padi) olfactory preference and the aphid parasitoid Lysiphlebus testaceipes. Even though Si accumulation in wheat did not impact aphid performance, we found that R. padi preferred constitutive volatiles from-Si wheat over those emitted by +Si wheat plants. In Y-tube olfactometer bioassays, the parasitoid was attracted to volatiles from +Si uninfested wheat, but not to those from-Si uninfested wheat. +Si and-Si aphid-infested plants released equally attractive blends to the aphid parasitoid; however, wasps were unable to distinguish +Si uninfested plant odors from those of aphid-infested treatments. GC-MS analyses revealed that +Si uninfested wheat plants emitted increased amounts of a single compound, geranyl acetone, compared to -Si uninfested wheat, but similar to those emitted by aphid-infested treatments. By contrast, Si supplementation in wheat did not alter composition of aphid-induced plant volatiles. Our results show that changes in wheat volatile blend induced by Si accumulation mediate the non-preference behavior of the bird cherry-oat aphid and the attraction of its parasitoid L. testaceipes. Conversely to the literature, Si supplementation by itself seems to work as an elicitor of induced defenses in wheat, and not as a priming agent., Competing Interests: The authors have declared that no competing interests exist.

Phosphine resistance is a worldwide issue threatening the grain industry. The cuticles of insects are covered with a layer of lipids, which protect insect bodies from the harmful effects of pesticides. The main components of the cuticular lipids are hydrocarbon compounds. In this research, phosphine-resistant and -susceptible strains of two main stored-grain insects, T. castaneum and R. dominica , were tested to determine the possible role of their cuticular hydrocarbons in phosphine resistance. Direct immersion solid-phase microextraction followed by gas chromatography-mass spectrometry (GC-MS) was applied to extract and analyze the cuticular hydrocarbons. The results showed significant differences between the resistant and susceptible strains regarding the cuticular hydrocarbons that were investigated. The resistant insects of both species contained higher amounts than the susceptible insects for the majority of the hydrocarbons, sixteen from cuticular extraction and nineteen from the homogenized body extraction for T. castaneum and eighteen from cuticular extraction and twenty-one from the homogenized body extraction for R. dominica . 3-methylnonacosane and 2-methylheptacosane had the highest significant difference between the susceptible and resistant strains of T. castaneum from the cuticle and the homogenized body, respectively. Unknown5 from the cuticle and 3-methylhentriacontane from the homogenized body recorded the highest significant differences in R. dominica . The higher hydrocarbon content is a key factor in eliminating phosphine from entering resistant insect bodies, acting as a barrier between insects and the surrounding phosphine environment., Competing Interests: The authors declare no conflict of interest.

The coexistence of cereal cyst nematode (CCN) species Heterodera avenae and H. filipjevi , often involving multiple pathotypes, is a limiting factor for wheat production in China. Some of the known genes for resistance to CCN are not effective against both nematode species, hence complicating breeding efforts to develop CCN-resistant wheat cultivars. Here, we demonstrate that the CCN resistance in wheat cultivar Madsen to both Heterodera spp. is controlled by different genetic loci, both of which originated from Aegilops ventricosa . A new quantitative trait locus (QTL), QCre-ma7D , was identified and localized in a 3.77-Mb genomic region on chromosome arm 7DL, which confers resistance to H. filipjevi . QCre-ma2A on chromosome arm 2AS corresponds to CCN resistance gene Cre5 and confers resistance to H. avenae . This QTL is a new locus on chromosome arm 7DL and is designated Cre9 . Three Kompetitive allele-specific PCR markers (BS00150072, BS00021745, and BS00154302) were developed for molecular marker-assisted selection of Cre9 and locally adapted wheat lines with resistance to both nematode species were developed. QCre-ma2A on chromosome arm 2AS corresponds to CCN resistance gene Cre5 and confers resistance to H. avenae . The identification of different loci underlying resistance to H. filipjevi and H. avenae and the development of adapted resistant entries will facilitate breeding of wheat cultivars that are resistant to these devastating nematodes in China.

Background: In this study, artificial intelligence models that identify sunn pest-damaged wheat grains (SDG) and healthy wheat grains (HWG) are presented. Svevo durum wheat cultivated in Konya province, Turkey is used for the process, with 150 HWG and 150 SDG being used for classification. Thanks to the constructed imaging setup, photos of the 300 wheat grains are obtained. Seventeen visual features of each wheat grain are extracted by image-processing techniques and evaluated in three different groups of dimension, texture and pattern as visual parameters. Artificial bee colony (ABC) optimization-based artificial neural network (ANN) and extreme learning machine (ELM) algorithms are implemented to classify the damaged wheat grains., Results: A correlation-based feature selection (CFS) technique is also utilized to find the most effective among the 17 features. In the classification process using five selected features, the mean absolute error (MAE) and root mean square error (RMSE) values for ABC-based ANN are calculated as 0.00174 and 0.00433 respectively. The proposed technique is integrated into graphical user interface (GUI) software to construct an effective detection system for practical use., Conclusion: The results indicate that, thanks to the modified ANN algorithm and implemented CFS algorithm, the detection accuracy of damaged wheat grains is considerably increased. © 2019 Society of Chemical Industry., (© 2019 Society of Chemical Industry.)