Crop Protection最新文献

Downy mildew disease, which is caused by Peronospora aestivalis (Mastigomycotina: Peronosporaceae) and the spotted alfalfa aphid Therioaphis trifolii (Hemiptera: Aphididae), affects Medicago sativa (alfalfa) production. P. aestivalis and T. trifolii frequently occur together under natural conditions. In this study, alfalfa-P. aestivalis-T. trifolii were used as the research objects to explore the effects of different degrees of P. aestivalis infection on the growth and reproduction of T. trifolii, and the life table of T. trifolii population was constructed based on the fecundity parameters. The results revealed that alfalfa downy mildew infection had a significant effect on T. trifolii population. T. trifolii fed on mildly infected alfalfa plants exhibited the longest life span (18.9 d) and the highest number of nymphs (30.6) compared to those fed on alfalfa in other treatments. In terms of population life table parameters, the intrinsic rate of increase (0.626) and finite rate of increase (1.869) of T. trifolii fed on moderately infected alfalfa were the highest, and the generation time (8.310) and population doubling time (1.108) were the shortest, indicating that moderately infected alfalfa are conducive to T. trifolii population development. This study provides insights into the effects of alfalfa downy mildew on the main reproductive parameters and population of T. trifolii on M. sativa.

In today's agriculture, weed management is a big challenge, globally, because of its negative effects on agricultural output and quality. Most agricultural production systems are dictated by the weed plant, which is a key barrier to advancing sustainable agricultural production systems. Weeds are the major constraint of the agroecosystem often uses nutrients more quickly and in greater quantities than crops which need to keep below the economic threshold. In a particular agro-ecosystem, weed and agricultural crop management strategies (such as tillage, fertilizer, and irrigation management) and environmental conditions have a substantial impact on weed seed and population dynamics. Furthermore, weed seed dormancy in weed-seed stock of preceding seasons has been stimulated by fertilization and weed growth along with changing soil conditions which impact weed community structures and crop development. Nitrogen (N), as an important macronutrient, is primarily involved in this process. However, organic amendments, their source, type, and duration of use depict their effectiveness. Furthermore, under variable climate, understanding crop–weed interference is also vital for sustainable agriculture; changes in global climate have significantly resulted in changes in weed flora throughout the globe. Extreme temperatures and drought can promote the growth of C4 weeds, spreading and invading perennial weeds. There are a variety of environmental factors that can impact weeds and crops' ability to exploit the environment's resources. In addition to influencing weed/crop interactions directly, environmental stresses like temperature and light may also interfere with (or supplement) weed control efforts. Therefore, this review summarizes the consequences of environmental stress and fertility variations on weed dynamics, nutrient uptake, and crop yield under different climate scenarios. However, agro-ecosystem balance can be improved by implementing integrated weed management operations and gaining knowledge on how fertilization impacts the density of noxious and hazardous weeds.

Lolium rigidum Gaud. (rigid ryegrass) is one of the most widespread weeds in cereal crops in Morocco, Algeria and Tunisia. This weed has evolved resistance to various herbicide modes of action in this region. ACCase and ALS inhibiting herbicides are mainly used in the major-cereal growing regions to control rigid ryegrass. Through a questionnaire, regions where farmers reported less control of herbicide treatments were registered in the three Maghreb countries. Registered fields were visited for collection and 75 field populations were screened with two ACCase and two ALS herbicides. Target site resistance (TSR) was diagnosed using Illumina Next Generation Sequencing (NGS) technology. The sensitivity bioassay results revealed over 60% of sampled populations to be resistant to pinoxaden and/or clodinafop and about 40% to be resistant to iodosulfuron + mesosulfuron and/or pyroxsulam. In addition, 53% of populations displayed resistance (R) to the two herbicide modes of action tested among the regions. In total, 16 ACCase and 11 ALS mutant alleles were identified, carrying out an amino-acid substitution and conferring herbicide resistance in 3700 of the analyzed plants. Most ACCase and ALS mutations were detected at codons Ile1781 and Pro197, respectively. Not only does this study demonstrate the presence of both cross and multiple resistance, it also highlights the non-ACCase and non-ALS -based resistance mechanisms that could confer resistance to herbicides with different modes of action which complicates the resistance management strategies. In the three Maghreb countries, this challenge is even more prominent due to few modes of action being available for rigid ryegrass control due to low-cost market and the prevalence of generic herbicides.

This study aimed to evaluate the nutritional and antifeedant indices of Tribolium castaneum in response to the compounds and main chemical constituents of Ajania potaninii and A. fruticulosa. These mainly includes essential oils and their major ingredients (eucalyptol, camphor, myrtenol, verbenol, and borneol), as well as nonvolatile compounds. The A. fruticulosa and A. potaninii EOs exhibited clear antifeedant activity against T. castaneum adults at a 2 mg/L concentration, with FDI of 50% and 60%, respectively. Among the nonvolatile compounds, sesamin and eriodictyol exhibit strong antifeedant activities against T. castaneum adults at the same concentration, with an FDI of 90.57% and 88.68% after 72 h, respectively. For larvae, A. fruticulosa and A. potaninii EOs also resulted in antifeedant activity (respective FDI: 57.08% and 55.63%). In addition, sesamin and eriodictyol had exceptionally potent antifeedant activity against T. castaneum larvae, with FDI values 90.71% and 96.17%, respectively. In nutritional studies, the reductions in relative food consumption rate (RCR) of T. castaneum were more pronounced for 1 mg/L and 2 mg/L of either eucalyptol or sesamin. However, at greater concentrations, the conversion efficiency of eucalyptol and sesamin to ingested food in T. castaneum was significantly improved. Eucalyptol and sesamin showed a dose-dependent FDI for this insect. Considering the significant anti-insect activities, the EOs, main compounds, and non-volatile compounds of both A. potaninii and A. fruticulosa might be useful in devising integrated pest strategies, providing a promising perspective for the comprehensive use of natural plant resources from the Ajania genus.

Cabbage stem flea beetle (CSFB) is an economically important pest of oilseed rape crops responsible for substantial yield losses in recent years, particularly since the restrictions on neonicotinoid seed treatment use came into force in 2013. To effectively time sowing dates and target control measures, it is crucial that accurate estimates of when migratory adult CSFB will arrive at the crop can be made. A Bayesian hierarchical model was fitted to data from 19 sites containing adult CSFB traps over a period of three years to characterise the relationship between the day of year, temperature, rainfall, wind speed and solar radiation on beetle counts and to understand their relative importance. Day of the year was identified as the main driver of migration and temperature was the predominant environmental driver of CSFB migration. A hot day (based on the range of observed temperatures over the trapping window) resulted in approximately 300% of the expected CSFB migration relative to an average day during peak migration. The second most important environmental driver of migration was wind speed, but this resulted in a relatively negligible increase of approximately 15% from an average day to a still day. These findings suggest that efforts to predict timing of adult CSFB migration should focus on understanding how the phenology of CSFB and temperature interact to drive the timing of migration.

Insect pests pose a global threat to crop yield. Biological control by natural enemies aims to reduce pest damage in a sustainable way. Cereal leaf beetles (CLB; Oulema spp.) are major pests in small-grain cereals. We studied the effect of natural enemies on CLB damage and its consequences on yield within its native distribution area in Europe. In exclusion cage experiments and by documenting a naturally occurring CLB damage gradient, we found that CLB damage reduced yield, but natural enemy action reduced the damage by CLB. Comparing exclusion and open treatments on artificially CLB-infested plants, plants accessible to natural enemies had 30% less leaf damage. CLB damage significantly affected yield parameters. Thousand grain weight was 22–29% less in maximum leaf damage scenarios. In the damage gradient field, maximal infestation reduced grain yield by 52%. However, maximal damage occurred only on a few plants and over small areas. In natural infestation cases, the number of CLB larvae per plant had a median of zero; nevertheless, there were more than 35 larvae on 10% of the plants. Patchiness explained 40% of CLB damage variance. Damage was unevenly distributed; as a result, thousand grain weight decreased only by 1.6% for 75% of the plants but by 18% for 10% of the plants. In the natural damage gradient, the estimated yield loss for the entire field was 16% due to CLB. Skewed CLB distribution may lead to perceptible yield losses locally, but natural enemies may limit overall damage to the crop.

One of the most devastating polyphagous pests in the world, Bemisia tabaci (Gennadius), causes significant damage to a variety of crops and has demonstrated the ability to develop resistance to different classes of insecticides rapidly. A novel pyridine azomethine derivative pyrifluquinazon exhibits exceptional insecticidal toxicity against B. tabaci by interrupting the function of chordotonal receptor neurons. Formulating resistance management strategies is crucial to ensure the long-term use of this insecticide for whitefly control; however, the characteristics and possible mechanisms of pyrifluquinazon resistance in B. tabaci remain unclear. By employing pyrifluquinazon selection for 22 successive generations, the pyrifluquinazon-resistant strain (PQZ-R) was generated from a laboratory-susceptible population of B. tabaci Asia I (Lab-WB) and exhibited 39.65-fold resistance to pyrifluquinazon. When the realized heritability (h²) of B. tabaci to pyrifluquinazon was assumed to be the laboratory-estimated value (h² = 0.181) and the mortality was 70–90%, only 12.3–22.6 generations were expected to be required to obtain a 10-fold increase in pyrifluquinazon resistance. While there was no significant cross-resistance to cyantraniliprole, dinotefuran, flonicamid, flupyradifurone, pymetrozine, sulfoxaflor, or thiamethoxam, the PQZ-R strain displayed slight cross-resistance to afidopyropen (3.14-fold). Synergism tests indicated that piperonyl butoxide (PBO) inhibits (4.36-fold) pyrifluquinazon resistance in the PQZ-R strain. This impact may be attributed to enhanced detoxification (elevated 3.91-fold) mediated by cytochrome P450 monooxygenase (P450). Compared to Lab-WB, the PQZ-R strain exhibited no significant overexpression of the 13 published detoxification-related P450 genes from CYP303, CYP4, and CYP6 families in B. tabaci. The combined knowledge gained from this study will enable further investigations into the function of qualitative and quantitative variations in P450-encoded genes, leading to innovative approaches for efficiently managing B. tabaci.

Crop damage by wild boar is a serious problem globally. Temporary electric fences, installed only during periods when the damage occurs, are widely used in Japan to prevent wild boar intrusion. The exclusion method is effective, but the cost burden involved makes considering cost-effectiveness necessary, especially for small-scale paddy rice farmers. Group fences may be used to reduce the cost burden. Although enclosing an area this way is effective, it may lead to free-riding when the scale of the project becomes large. Measures like reducing the number of people involved are suggested, but few indicators exist regarding the appropriate scale of management. Therefore, in Chiba Prefecture, where the distribution of wild boar is expanding, we conducted i) a six-year survey on the amount of damage to paddy rice fields in the Awa region; ii) an evaluation of the cost-effectiveness of temporary electric fences; and iii) an extrapolation of the cost-effectiveness to the entirety of Chiba Prefecture. The results show that the optimal installation length can be calculated by considering the maximum damage area, but without a government subsidy, the fence cost-effectiveness will be low because the installation cost will exceed the maximum damage amount. A group enclosure of small farmlands, which is not currently cost-effective in Chiba Prefecture, is recommended as a management decision for planners and farmers in future damage control plans. Although the empirical data were specific to small-scale farmers in Japan, the validation process was considered broadly applicable.

The development of commercial varieties that are resistant or tolerant to crown rot caused by Fusarium species is an important goal for cereal breeding programs internationally. Ideally, this research requires experimental sites that are initially free from Fusarium in order to establish treatment plots that compare growth in the presence and absence of these soil- and stubble-borne pathogens. Specifically, the assessment of tolerance requires control plots free of disease to determine the reduction in crop yield in plots where the disease is present. The ability of soil solarisation to reduce the background Fusarium pseudograminearum level occurring at experimental sites in comparison to current stubble management techniques was investigated across three field trials at Wellcamp in Queensland. Stubble from a susceptible durum (Triticum turgidum ssp. durum) cultivar inoculated with F. pseudograminearum was incorporated by cultivation into the trial sites to establish a significant background level of inoculum prior to the application of all subsequent treatment plots. In these trials, solarisation over a period of twelve weeks reduced the presence of F. pseudograminearum to low detection levels when compared to the traditional crown rot management techniques of cultivation or growth of the non-host cover crops mungbean (Vigna radiata) and soybean (Glycine max). No negative effects of solarisation were observed on a subsequent crop of bread wheat (Triticum aestivum), with significantly higher yields observed in the solarised treatments. Solarisation has the potential to deliver near zero level crown rot reference sites for experimental purposes in one short application between cropping seasons.

Stripe rust is one of the main diseases of wheat, which seriously threatens wheat production and food security all over the world. Xiangyang located in the Northwest of Hubei province in China is one of the main winter propagation and spring epidemic regions of Puccinia striiformis f. sp. tritici (Pst), which can provide urediniospores to the major wheat-growing regions in eastern and northeastern China. Understanding the dynamic of Pst urediniospore is important for giving prediction of wheat stripe rust epidemic for eastern and northeastern China and controlling the epidemic of wheat stripe rust. In this study, spore trapper and TaqMan real-time quantitative PCR (TaqMan-qPCR) detection system were employed to monitor Pst urediniospore from December 2018 to December 2022 in Xiangyang. Weather variables including air temperature, relative humidity, sunshine duration and rainfall were collected to clarify the relationship with urediniospore density in the air. In addition, the relationship between disease index of wheat stripe rust and urediniospore density in the air was analyzed. Results showed that Pst urediniospore could be captured in the air all year round. The order of the density of urediniospore from most to least was from April to June, October to December, January to March, and July to September except 2022. The urediniospore density reached the peak when the air temperature was 10–22 °C and the relative humidity was 70%∼85% from April to May in 2019, 2020 and 2021. The density of Pst urediniospores from February to April was linearly related to the total precipitation of 25 days prior to the final day of a 7-day trapping period. There was a significant positive correlation between the disease index of wheat stripe rust and the cumulative urediniospore density 2–4 weeks before the investigation date of wheat stripe rust from March to May (P < 0.05). There was no significant correlation between the disease index and the cumulative urediniospore density from 1–4 weeks after the investigation date of stripe rust from March to May (P > 0.05). This study laid a foundation for the establishment of wheat stripe rust prediction model based on urediniospore density and meteorological factors.