Pest Of Wheat Research Articles

Genome-wide identification and characterization of the TPS gene family in wheat (Triticum aestivum L.) and expression analysis in response to aphid damage

Terpene synthase (TPS) gene family is ubiquitous in land plants and plays an important role in regulating various biological processes in plants, especially in pathogen and herbivore defense mechanisms. Also, little is known about this gene family in wheat. In this research, 153 TaTPS genes were identified and named according to their chromosome location. Phylogenetic analysis of TaTPS proteins and other homologous proteins corresponded to a six-subgroup classification. The analysis of gene structure and motif showed that the TaTPS gene was highly conserved in each subgroup, which suggested that whole genome duplication and segmental duplication events were the main expansion way of the TaTPS gene family. Nineteen tandem duplication gene pairs and 91 homologous genes on different chromosomes were produced by segmental duplication. Expression profiles derived from transcriptome data results indicated that TaTPS genes may contribute to defense responses of wheat to pests such as aphids. The cis-regulatory elements (CREs) of TaTPS were found to be diversified indicating that TaTPS gene may participate in many physiological processes of wheat growth and development. Each TaTPS gene contains at least two or more defense or hormone-related CREs, suggesting an important role in wheat pest defense through hormone pathways. This study can provide valuable clues for elucidating the evolutionary relationship of the TaTPS gene family. Also, it may provide a research basis for functional investigations related to wheat development, particularly to plant–pest interactions and further breeding for new wheat varieties with aphid resistance.

Feeding preference and reproductive fitness of Rhyzopertha dominica (Fabricius, 1792) in a choice-based feed paradigm

Objective: This study is designed to understand the feeding preference of R. dominica, when three grains and their flours are provided in a choice- paradigm, constructed in the form of a poly vinyl chloride tunnel, in which feed materials are made available at random. Methods and Analysis: A total of 200 beetles were released into the choice-paradigm, and the number of beetles in each feed was counted once in every 24 h. When the beetles in the choice chamber were enumerated after 96 h, 26 percent of the released beetles were found in wheat grain; 25% in wheat flour; 12 in rice; 11 in chick pea; 10 in rice and chick pea flours and 6% in the outer tunnel without opting for any feed. On the basis of the feed on which R. dominica were reared, changes were observed in selected key biological characteristics. Findings: The research findings showed that wheat and wheat flour were preferred against rice, chick-pea and their flours. The incubation period increased significantly (51%) when reared in chick pea flour. In beetles reared on this feed, total larval period increased by 39%, pupal period by 31% and total developmental period by 39%. The fecundity decreased by 11%, whereas, male and female longevities respectively by 20% and 24%. Egg hatching was not much affected by the type of feed. Hatchability was 92% for wheat flour and 97% for rice and chick pea grains. Novelty: R. dominica, a primary pest of stored wheat, seemed to possess the evolutionary plasticity to survive in a variety of feed materials when the primary diet is not available. Keywords: Rhyzopertha dominica; Triticum aestivum; Oryza sativa; Cicer arietinum; feeding preference

Green Synthesis of Silver Nitrate Nanoparticles from Camelina Sativa (L.) and Its Effect to Control Insect Pests of Stored Grains

Oryzaephilus surinamensis (L.) and Sitophilus granarius (L.) are major pests of stored wheat, Triticum aestivum (Linn.) and cause huge economic loss to it. This study aimed to evaluate the toxic and repellent effects of Camelina sativa (L.) extract using green synthesis of silver nanoparticles against O. surinamensis and S. granarius. The bioassays were performed by applying three concentrations (5, 10 and 15%) of C. sativa extract and 200, 300 and 500 ppm in case of silver nanoparticles. Mortality was recorded at 24, 48 and 72 h while repellency was noted after 12, 24, and 36 h of the post-treatment. After 72 h of exposure, the highest concentration of C. sativa extract (15%) caused mortality of 43.1 and 35.2% to O. surinamensis and S. granarius, respectively. In repellency bioassays, the extract of C. sativa caused 37.7 and 30.2% repellency against O. surinamensis and S. granarius after exposure period of 36 h. While the highest mortality of 60.1% was observed against O. surinamensis at highest concentration (500 ppm) of the silver nanoparticles of C. sativa extract compared to S. granarius (46.2%) at same concentration after exposure period of 72 h. Highest repellency (42.7%) was observed against O. surinamensis at 500 ppm of the silver nanoparticles of C. sativa extract compared to S. granarius (36.2%) at same concentration after exposure to 36 h. The results revealed that green synthesized silver nanoparticles from C. sativa extract proved effective and can be used as eco-friendly management strategy of O. surinamensis and S. granarius.

Transcriptional Responses of Resistant and Susceptible Wheat Exposed to Wheat Curl Mite.

(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.

Analysis on Wheat Planting Technology and Pest Control Countermeasures

Analysis on Wheat Planting Technology and Pest Control Countermeasures

Mayetiola destructor (Diptera: Cecidomyiidae) host preference and survival on small grains with respect to leaf reflectance and phytohormone concentrations

The Hessian fly Mayetiola destructor (Diptera: Cecidomyiidae) 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.

Characterization and virulence of entomopathogenic fungi from sunn pests in Turkey

• B. pseudobassiana is the most prevalent and virulent species on sunn pests ( Eurygaster spp.). • C. farinosa , P. lilacinum , and C. rosea are other species identified on sunn pests ( Eurygaster spp.). • Some B. pseudobassiana isolates produce red pigment on MEA medium. • M. anisopliae has not been isolated directly from sunn pests in Turkey. The sunn pests ( Eurygaster spp.) which are important pests of wheat and barley, can lead to 100% yield loss in the case of an epidemic. This study was conducted to characterize the entomopathogenic fungi, obtained from the sunn pests collected from different overwintering areas of Turkey and determine their pathogenicity. Seventeen Beauveria pseudobassiana , 12 Beauveria bassiana , 16 Cordyceps farinosa , 1 Purpureocillium lilacinum , and 2 Clonostachys rosea species were identified. Pathogenicity tests were performed with three B. pseudobassiana , two B. bassiana , four C. farinosa , and one P. lilacinum isolates. B. pseudobassiana isolates BB34 and AF4 caused 100% death on the 9th day, and another B. pseudobassiana isolate E512 caused 100% death on the 12th day. C. farinosa isolate KOKA2 caused 95.8% death on the 15th day. Ultimately, B. pseudobassiana was determined to be the most prevalent and virulent species on sunn pests.

Characterization of wheat curl mite resistance gene Cmc4 in OK05312

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 ~ 523kb 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 CmcTAM112 in TAM112 might be the same gene as Cmc4.

Deterioration of Grain Quality of Wheat by Rice Weevil, Sitophilus oryzae (L.) during Storage

Background: A number of storage pests viz., Rhyzopertha dominica (F.), rice weevil, Sitophilus oryzae (L.), granary weevil, Sitophilus granarius (L.) and Khapra beetle, Trogoderma granarium (Evert.) damage stored wheat. However, S. oryzae is considered a primary pest of stored wheat and has been reported to prefer soft textured wheat cultivars.Methods: The grains of three bread (soft textured) viz., HD2967, PDW314, PBW658 and three durum wheat (hard textured) cultivars viz., WHD943, PBW621, PDW291 were screened for feeding response by rice weevil, Sitophilus oryzae L. in the laboratory. Each cultivar seed was properly cleaned and disinfested before its use. A 100g seed sample of each cultivar was taken into the plastic jars. Of the pure culture, ten 1-2 week young one insects (1:1 sex ratio) were released into the jars each containing different cultivar grains. The jars were covered with white muslin as three separate storage sets, i.e., 30, 60 and 90 days after storage to record data observations. Result: Durum wheat cultivars being low in protein contents were comparatively less preferred for pest feeding and cultivar PDW291 was found highly resistant based on low insect emergence, grain damage and weight loss. The bread wheat cultivars due to high protein contents were highly preferred by the pest and cultivar HD2967 showed maximum preference. The biochemical properties like ash contents and crude fibres showed positive while crude fats and protein a negative correlation with the pest infestation.

Characterization of Two Small Heat Shock Protein Genes (Hsp17.4 and Hs20.3) from Sitodiplosis mosellana, and Their Expression Regulation during Diapause.

Simple SummarySmall heat shock proteins (sHsps) play important roles in thermal adaptation of various organisms, and insect diapause. Sitodiplosis mosellana, a key pest of wheat worldwide, undergoes obligatory larval diapause in soil to survive adverse temperature extremes during hot summers and cold winters. The objectives of this study were to characterize two sHsp genes from S. mosellana (SmHsp17.4 and SmHsp20.3), and determine their expression in response to diapause, extreme high/low temperatures, or 20-hydroxyecdysone (20E) treatment. Expression of SmHsp17.4 was down-regulated upon entry into diapause, but up-regulated during the shift to post-diapause quiescence. In contrast, expression of SmHsp20.3 was not affected by entry into diapause, but was pronounced during summer and winter. Furthermore, transcripts of both SmHsps were highly responsive to heat (≥35 °C) and cold (≤−5 °C) during diapause, and topical application of 20E on diapausing larvae also induced SmHsp17.4 in a dose-dependent manner. Notably, the recombinant SmHsp17.4 and SmHsp20.3 exhibited significant molecular chaperone activity. In conclusion, SmHsp17.4 and SmHsp20.3 play essential roles in heat/cold adaptation, and 20E-mediated SmHsp17.4 was also likely involved in diapause termination. Results have improved our understanding of the molecular mechanism underlying diapause and related stress tolerance in S. mosellana.Sitodiplosis mosellana, a periodic but devastating wheat pest that escapes temperature extremes in summer and winter by undergoing obligatory diapause. To determine the roles of small heat shock proteins (sHsps) in diapause of S. mosellana, we characterized two sHsp genes, SmHsp17.4 and SmHsp20.3, from this species. Both SmHsps contained the conserved α-crystallin domain and the carboxy-terminal I/VXI/V motif of the sHsp family. SmHsp17.4 had one intron while SmHsp20.3 had none. Quantitative PCR revealed that SmHsp17.4 expression decreased after diapause initiation, but substantially increased during transition to post-diapause quiescence. In contrast, SmHsp20.3 expression was not affected by entry of diapause, but was clearly up-regulated during summer and winter. Short-term more severe heat-stress (≥35 °C) of over-summering larvae or cold-stress (≤−5 °C) of over-wintering larvae could stimulate higher expression of both genes, and SmHsp17.4 was more responsive to cold stress while SmHsp20.3 was more sensitive to heat stress. Notably, transcription of SmHsp17.4, but not SmHsp20.3, in diapausing larvae was inducible by 20-hydroxyecdysone (20E). Recombinant SmHsp17.4 and SmHsp20.3 proteins also displayed significant chaperone functionality. These findings suggest that both SmHsps play key roles in stress tolerance during diapause; and 20E-regulated SmHsp17.4 was also likely involved in diapause termination.

Effects of host plants on the population parameters and activities of detoxification enzymes in Laodelphax striatellus

AbstractThe small brown planthopper (SBPH), Laodelphax striatellus (Fallén) (Hemiptera: Delphacidae), is an economically important pest of rice (Oryza sativa L.), wheat (Triticum aestivum L.), and other members of the Poaceae. The effects of host plant type on SBPH life table parameters reared on two cultivars of rice (Zixiangnuo 2315 and Wuyujing 3), wheat (Jimai 22 and Nongda 26), and one grass weed (Echinochloa crusgalli Beauv.) under laboratory conditions were determined using the age‐stage, two‐sex life table. Additionally, the corresponding activities of three detoxifying enzymes – carboxylesterase (CarE), glutathione‐S‐transferase (GST), and mixed‐function oxidase (MFO) – were also measured. The results showed that host plant species and cultivars had effects on population parameters and activities of detoxification enzymes. Rice cv. Zixiangnuo 2315 and wheat cv. Nongda 26 were shown to be more suitable than the other three hosts. The activities of the three detoxifying enzymes showed different patterns of changes on the three host plants after feeding for 0–72 h. Regardless of short‐term (72 h) or long‐term (one generation) induction on host plants, the activity levels of GST and MFO in adult SBPH reared on rice ‘Zixiangnuo 2315’ were lower and higher, respectively, than on the other four hosts. The results may help understand the host adaptability of this pest and inform the development of strategies for effective field‐based integrated pest management programs.

Susceptibility of Four Species of Aphids in Wheat to Seven Insecticides and Its Relationship to Detoxifying Enzymes.

Sitobion avenae (Fabricius), Rhopalosiphum padi (Linnaeus), Schizaphis graminum (Rondani), and Metopolophium dirhodum (Walker) (Hemiptera: Aphididae) are important pests of wheat and other cereals worldwide. In this study, the susceptibilities of four wheat aphid species to seven insecticides were assessed. Furthermore, the activities of carboxylesterase (CarE), glutathione S-transferase (GSTs), and cytochrome P450 monooxygenase (P450s) were determined in imidacloprid treated and untreated aphids. The results showed that the susceptibilities of four wheat aphid species to tested insecticides are different and M. dirhodum has shown higher tolerance to most insecticides. Relatively higher CarE and GST activities were observed in M. dirhodum, and P450s activities increased significantly in response to imidacloprid treatment. Moreover, susceptibility to imidacloprid were increased by the oxidase inhibitor piperonyl butoxide in M. dirhodum (20-fold). The results we have obtained imply that P450s may play an important role in imidacloprid metabolic process in M. dirhodum. We suggest that a highly species-specific approach is essential for managing M. dirhodum.

Seasonal emergence patterns ofSitodiplosis mosellana(Diptera: Cecidomyiidae) in the Peace River region, Alberta, Canada

AbstractWheat midge,Sitodiplosis mosellanaGéhin (Diptera: Cecidomyiidae), is an invasive pest of wheat,Triticumspp. (Poaceae), in North America and is found in all wheat-growing regions of the world. Wheat midge biology, particularly post-diapause emergence of adults, varies with geographic region. The biology of wheat midge has not previously been examined in the northernmost area of its range in Canada – the Peace River region of Alberta. Wheat midge adult emergence was comparedin situto two phenological models of wheat midge emergence developed in other geographic regions. In-field adult emergence did not match the published phenological models. In the Peace River region, adults emerged later than are predicted by both models and precision for both models was low. With the Saskatchewan model, accumulated rainfall that was more than 110 mm in May and early June delayed emergence, whereas accumulated rainfall that was less than 43 mm during that period caused earlier than predicted emergence. Multiple peaks of wheat midge emergence, up to 20 days apart, were observed at some sites, supporting the Jacquemin model depicting “waves” of emergence. Including differences in soil temperature accumulation related to precipitation and optimising the model temperature thresholds would improve accuracy of the current Canadian phenological model in the Peace River region.

Interaction between the Bird Cherry-Oat Aphid (Rhopalosiphum padi) and Stagonospora Nodorum Blotch (Parastagonospora nodorum) on Wheat.

Simple SummaryThe bird cherry-oat aphid and the fungal plant pathogen causing stagonospora nodorum blotch (SNB) are common pests of wheat. Plants are under constant attack by multiple pests and diseases but there are limited studies on the interaction between several pests on wheat. We therefore conducted controlled greenhouse and laboratory experiments to determine how these pests affected each other on a wheat plant. We found that aphid feeding predisposed wheat to fungal disease, but that aphids preferred and reproduced better on leaves that had not been infected by the fungal pathogen. These results are important to understand the interactions between multiple pests on wheat and how to develop new control strategies in future integrated pest management (IPM).Wheat plants are under constant attack by multiple pests and diseases. Until now, there are no studies on the interaction between the aphid Rhopalosiphum padi and the plant pathogenic fungus Parastagonospora nodorum causal agent of septoria nodorum blotch (SNB) on wheat. Controlled experiments were conducted to determine: (i) The preference and reproduction of aphids on P. nodorum inoculated and non-inoculated wheat plants and (ii) the effect of prior aphid infestation of wheat plants on SNB development. The preference and reproduction of aphids was determined by releasing female aphids on P. nodorum inoculated (SNB+) and non-inoculated (SNB−) wheat leaves. The effect of prior aphid infestation of wheat plants on SNB development was determined by inoculating P. nodorum on aphid-infested (Aphid+) and aphid free (Aphid−) wheat plants. Higher numbers of aphids moved to and settled on the healthy (SNB−) leaves than inoculated (SNB+) leaves, and reproduction was significantly higher on SNB− leaves than on SNB+ leaves. Aphid infestation of wheat plants predisposed the plants to P. nodorum infection and colonization. These results are important to understand the interactions between multiple pests in wheat and hence how to develop new strategies in future integrated pest management (IPM).

Effects of Landscape Composition on Wheat Stem Sawfly (Hymenoptera: Cephidae) and Its Associated Braconid Parasitoids.

Several agroecological and integrated pest management strategies focus on landscape management to increase complexity and foster biodiversity. However, landscape complexity does not always enhance biological control and in some cases may lead to increased pest populations. We examined the prevalence of two Bracon parasitoids, Bracon cephi Gahan and Bracon lissogaster Muesebeck (Hymenoptera: Braconidae), and their host the wheat stem sawfly Cephus cinctus Norton, a major pest of wheat. We assessed the degree of noncrop and crop host plant use and responses to landscape composition. We found no instances of parasitism by either Bracon species in our three-year, statewide winter wheat survey but found small populations of Bracon in noncrop landscapes throughout eastern and western Colorado. We used model selection to examine how local (500 m scale) and landscape (5 km scale) cover of suitable noncrop and crop habitats potentially affects abundances of Bracon and wheat stem sawfly. Our best fit model for wheat stem sawfly suggests that a decrease in noncrop cover at the landscape scale leads to an increase in wheat stem sawfly infestation. Our best fit model for Bracon parasitism suggests an increase in wheat cover at the local level results in the greatest increase in the odds of parasitism by either species of Bracon. Herbaceous cover at local and landscape scales were also significant predictors of Bracon parasitism. The results of this study suggest that pest and natural enemies respond differently to landscape composition and these responses should be evaluated before management decisions are made.

The wheat curl mite (Aceria tosichella, Prostigmata: Eriophyidae) could establish in South Africa

Biological invasions by agricultural pests can have serious negative impacts, including decreases in crop yield and economic losses. The MT-1 and MT-8 genotypes of the wheat curl mite (Aceria tosichella) (hereafter ‘WCM’ refers to these two genotypes) are globally distributed pests of wheat and maize that have not been recorded in South Africa. This study examined whether WCM could be introduced to, and establish in, South Africa. Trade data were used to determine whether viable pathways of introduction are present. A species distribution model and data on wheat and maize production were used to determine whether WCM could establish where its hosts are grown. WCM is most likely to be introduced to South Africa as a contaminant of maize from Argentina, Brazil, Uruguay, and USA; on live plant imports from China and Germany; and on seed imports from Brazil and Australia. Some of these pathways are not currently prominent, but could increase in the future. Parts of South Africa were predicted by the species distribution model to be climatically suitable for WCM, and within some of these areas the host crops are grown. Therefore, if WCM is introduced, it is likely to establish and cause extensive damage to agriculture. We recommend that WCM be considered for inclusion in South Africa’s import conditions as a quarantine pest.

Wheat Yield in a Tolerant Winter Wheat Line Infested by Hessian Fly (<i>Mayetiola destructor</i>)

The Hessian fly, Mayetiola destructor, is a harmful pest of wheat (Triticum aestivum). Pioneer variety 25R78 is putatively tolerant, meaning that the plant can survive successful Hessian fly infestation with reduced growth effects. To understand if Hessian fly-tolerance in wheat results in reduced yield effects and to analyze the economic feasibility of tolerant wheat as a Hessian fly control method, this study focused on analyzing the effect of infestation on tolerant wheat yield. This study analyzed tolerant Pioneer variety 25R78, resistant Pioneer brand variety 25R32, and susceptible Pioneer brand variety 25R47 through harvest. Treated plants were infested using a plastic cover and allowing 1 - 2 female flies to lay eggs for two hours. We measured head, fertile head number and tiller number. Seeds were analyzed by measuring total seed number and weight, as well as average seed number and weight. Tolerant and resistant plants showed no significant effects on yield in comparison to susceptible wheat. The infested tolerant plants were comparable in yield to infested resistant plants. Therefore, we propose that tolerance incorporated into wheat varieties will lower selection pressure on Hessian fly populations and increase the durability of these wheat lines.

Вплив систем землеробства та обробітку грунту на основних шкідників пшениці озимої

The intensification of agriculture has a number of negative consequences, and the conservation of land resources during their active exploitation is an important problem nowadays, paying attention to the ever-growing food increase necessity. The world organic farming practice shows that we are very limited in the agricultural crops pests regulation. Artificial natural enemies increasing and the landscape altering to enhance biological control are not popular solutions and have contradictory efficiency. Monitoring of the winter wheat entomocomplex number was carried out according to conventional methods. It was performed at 48 plots, where 12 variants were placed in 4 replicates during 2019 - 2021. The article contains the research results show that farming systems have a significant impact on the main winter wheat pests, and that they can control the ecological system at the level of the economic harm threshold. The way the soil was treated did not change the number of Schizaphis graminum R., Eurygaster integriceps P., and Oulema melanopus L., while chisel cultivation of 20–22 centimeters provided regulation of Anisoplia austriaca H. and Haplothrips tritici Kurd number way more below the dangerous level for years of observation. Whenever the soil was treated to a depth of 6-8 centimeters, the number of these pests increased significantly and varied from 2.0 ind./m2 to 14.4 ind./m2. Therefore, this data shows the efficiency of insecticidal winter wheat treatments multiplicity reduction in an ecological system without the risk of crop loss due to the plant damaged by pests in combination with chisel soil cultivation.

Impact of resistance to fenitrothion and esfenvalerate on the control of Rhyzopertha dominica (Coleoptera: Bostrichidae) in stored wheat

Insecticides resistance can significantly compromise the control programs of Rhyzopertha dominica (Coleoptera: Bostrichidae), one of the main wheat pests in warehouses. The objectives of this work were to study the occurrence of resistance to fenitrothion and esfenvalerate in two Brazilian populations of R. dominica from Santa Rosa (SR lineage) and Campo Grande (CG lineage), as well as the insecticidal effect and residual action of these insecticides when used alone or as a mixture in stored wheat. The application system was calibrated to provide grain treatment at theoretical concentrations of 10 and/or 0.5 mg kg-1 fenitrothion and esfenvalerate, respectively. By comparing the fitted mortality curves for lineages within insecticides, as well as insecticides within lineages significant differences were observed in all cases. Esfenvalerate was ineffective in controlling R. dominica. The SR lineage of R. dominica was more resistant to the insecticides tested than the CG lineage. The number of individuals in the F1 offspring of R. dominica was dependent on the lineage, insecticide, and on the time after the application of insecticide. In the untreated grains (control), the CG lineage had a greater number of progeny than the SR lineage, while the opposite was verified in the grains treated. Fenitrothion and esfenvalerate are not useful for the control of R. dominica. Factors influencing control of R. dominica are discussed in this work.

Pantoea ananatis, A New Bacterial Pathogen Affecting Wheat Plants (Triticum L.) in Poland.

Wheat (Triticum aestivum) is one of the most economically important crops in the world. During the routine monitoring of wheat pest, the cereal leaf beetle (CLB, Oulema melanopus, Coleoptera, Chrysomelidae), in the Greater Poland region, it was observed that some leaves wounded by CLB also displayed brownish lesions with clear margins and yellow halo, disease symptoms resembling a bacterial infection. The aim of this study was therefore to investigate those symptoms to establish a causal agent of the disease. The identification based on the results of the Biolog’s Gen III system, 16S rRNA, and gyrB genes sequencing, revealed the presence of eight strains of Pantoea ananatis bacteria. Four strains were derived from wheat leaves (Ta024, Ta027, Ta030, Ta046), and four from the CLB’s oral secretion (OUC1, OUD2, OUF2, and OUG1). They shared the nucleotide identity ranging from 99 to 100% to P. ananatis strains deposited in the GenBank database. Additionally, the multi-locus sequence analysis (MLSA) of concatenated sequences of partial atpD, fusA, gyrB, rplB, and rpoB genes was performed. All P. ananatis strains isolated in Poland, grouped into one cluster supported with high bootstrap value. Pathogenicity tests performed on four varieties of wheat plants have identified P. ananatis strains as a causal agent of wheat disease. To our knowledge, this is the first report of P. ananatis affecting wheat plants.