查看更多>>摘要：? 2022 Elsevier LtdPotato production in Cameroon is constrained by biotic factors including bacterial wilt disease caused by Ralstonia solanacearum. No single method effectively controls this disease. Breeding for resistance is usually the best option for disease control in crops. Screening the potential parents for resistance under the target environmental conditions is the prerequisite for effective resistance breeding. This study aimed to determine the response to bacterial wilt of selected potato genotypes grown under different elevation levels and to identify suitable parents that can be used to develop resistant cultivars. The study was carried out in three elevations [high (>1800 m above sea level (m.a.s.l)), medium (1400–1800 m.a.s.l) and low (<1400 m.a.s.l)] in the Western Highlands zone of Cameroon. Seven potato genotypes were planted in a field of each elevation using a Complete Randomized Block Design with three replications. Inoculation occurred naturally. Disease parameters collected included days to onset wilting and bacterial wilt incidence (BWI). Yield components such as the total number of tubers per plant, the percentage of unmarketable tubers and the marketable yield were recorded. BWI as well as the percentage of unmarketable tubers decreased with elevation, meanwhile marketable yield increased with elevation. Disease development tended to be lower in all cultivars at higher elevations. The resistance of Dosa, Desiree, and Banso was high in all environments. based on these results, the combination of these two methods can lower the impact of bacterial wilt. Dosa can be grown at higher elevation fields for stable and higher yields.
查看更多>>摘要：? 2022 Elsevier LtdTetranychus urticae Koch is a serious pest of strawberries and its remarkable ability to develop resistance has often caused failure in chemical control. In the present study, resistance to spiromesifen was detected in two out of nine field-populations of T. urticae collected from important strawberry production areas in Turkey, with resistance ratio's mounting to 60- and 140-fold. Synergism assays showed the involvement of detoxification enzymes, especially cytochrome P450 monooxygenases, in resistance against spiromesifen in field-collected T. urticae populations. We further selected the most resistant field-collected population (POP14) with spiromesifen and obtained an extremely resistant population (LC50 > 5000 mg a.i./L). Gene expression analysis with qPCR supported the involvement of cytochrome P450s in spiromesifen resistance in this selected population. In addition, we also detected a higher expression of acetyl-CoA carboxylase (ACCase), the target-site of spiromesifen, in the spiromesifen-selected population. Furthermore, a F1640L mutation in the conserved region of CT-domain of ACCase was uncovered in the most resistant field populations, but the role of this mutation in spiromesifen resistance needs further validation. Overall, spiromesifen still seems to be an effective tool in the control of T. urticae in strawberry production areas of Turkey, but resistance is on the rise and should be considered a serious threat.
查看更多>>摘要：? 2022 Elsevier LtdWheat powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a widespread airborne fungal disease which seriously threatens wheat production worldwide. Resistance to the disease can be lost quickly due to the limited number of resistance genes in wheat varieties and the high variation of powdery mildew pathogen. Therefore, it is critical to explore new resistance genes to breed durable resistant wheat varieties. The objectives of this study were to evaluate powdery mildew resistance at the seedling and adult stages, and to detect the presence of Pm genes in 332 germplasms from an international wheat collection using molecular markers. It was determined that only seven, four, and two accessions were resistant to Bgt races E09, E15, and A13, respectively. All tested accessions were fully susceptible to Bgt race A44 at the seedling stage. A total of 34 accessions were resistant at the adult plant stage. Molecular tests of the known Pm genes showed that 107 accessions did not contain any Pm genes. Additionally, 119 accessions were found to carry Pm38, 113 may have carried Pm8, 27 may have carried Pm21, 22 may have carried Pm60, 16 may have carried Pm24, 16 may have carried Pm41, 5 may have carried Pm5e, 2 may have carried Pm46, and Pm2a was not detected. By characterizing the resistance of an international wheat collection to powdery mildew, this study provides new sources for expanding genetic diversity and developing new wheat varieties with durable resistance to powdery mildew.
查看更多>>摘要：? 2022The wavelength of light can affect reproduction and development of arthropods. In the present study, we examined the reproduction and development of predatory thrips Scolothrips longicornis Priesner (Thysanoptera: Thripidae) fed on Tetranychus urticae Koch (Trombidiformes: Tetranychidae) eggs, under five wavelengths: white (all wavelengths), blue (475 nm), green (580 nm), yellow (620 nm) and red (675 nm), at 25 ± 0.5 °C, 16L: 8D and 60 ± 10% rh. Light wavelength did not significantly influence female and male preadult duration, male adult duration, and male total longevity. White and blue light yielded the longest oviposition periods. All life table parameters varied significantly among treatments. The intrinsic rate of increase (rm d?1) was lowest in red light wavelength (0.112 ± 0.009) and highest in white wavelength (0.171 ± 0.008) and blue light wavelength (0.168 ± 0.008). The present research demonstrates that white light conditions positively influence S. longicornis with shorter development time and improved reproductive performance. This information will be beneficial in mass production of S. longicornis for biocontrol programs involving T. urticae.
查看更多>>摘要：? 2022Looking for alternatives for the management of the olive tree moth, Palpita forficifera Munroe (Lepidoptera: Crambidae), this study evaluated the lethal toxicity of three formulations prepared from ethanol extracts from seeds of pre-selected species of Annonaceae (Annona mucosa Jacq., Annona muricata L. and Annona sylvatica A. St.-Hil) compared to a synthetic insecticide based on spinosyn (spinetoram 75 mg L?1, Delegate? 250 WG). At the concentration of 2,000 mg L?1, the formulation based on A. mucosa extract (major compound = acetogenin rolliniastatin-1) was the most promising treatment, presenting ovicide and larvicide effects comparable or superior to the synthetic insecticide used. In addition to lethal toxicity, P. forficifera third instar larvae fed on olive leaves treated with the formulation based on A. mucosa extract (LC50 = 11.91 mg L?1) showed a significant reduction in larval viability (?52%), larvae weight (?21%), pupal weight after 24 h (?11%) and total female fecundity (?17%) compared to the negative control. In semi-field conditions (greenhouse), the promising results obtained in the laboratory were confirmed, with the formulation of the aqueous emulsion of A. mucosa extract [(a at LC90 previously estimated at 24 h (987.11 mg L?1)], presenting a residual effect (≥80% mortality of third instar larvae) within approximately 7 days. Given the results, the formulation based on the ethanol extract of A. mucosa seeds is a promising alternative for the control of P. forficifera larval populations, especially in organic and/or ecological-based production systems.
查看更多>>摘要：? 2022 Elsevier LtdAsian rust is responsible for significant reductions in soybean yield. The application of fungicide is the main method of control of this disease, and to maintain the efficiency of phytosanitary treatment it is necessary to know several features of the application technology. Spray tips are fundamental for the quality of phytosanitary products application and exert a direct influence on spraying efficiency. The objective of this study was to evaluate the efficiency of different spray tips in spray deposition and leaf cover in the lower, middle and upper thirds of soybean plants in three distinct phenological stages. Another objective was to evaluate the efficiency of the commercial mixture trifloxystrobin + prothioconazole (FOX?), applied by different spray tips, in the control of Asian rust and soybean yield. The experiment was conducted for two agricultural years, and six spray tips were evaluated: TT 11001, TTJ60 11002, TXA 8003, 30HCX 12, GRD120 02 and GAT11002 in three fungicide applications with intervals of 15 days, in the phenological stages V6–V7, R1 and R4, using the working pressure of 5 bar and spray volume of 200 L ha?1. The coverage and deposition of spray promoted by all spray tips, in the three phenological stages of soybeans, were sufficient to provide satisfactory control of rust, with means of disease severity ranging from 1.69 to 4.70%, compared to the control (mean severity of 54.34%), without significant loss of yield in the sprayed plots. All evaluated spray tips can be recommended for use in spraying FOX? fungicide (trifloxystrobin + prothioconazole) in soybean crop for Asian rust control, when the spray volume applied is 200 L ha?1.
查看更多>>摘要：? 2022 Elsevier LtdMore than one-third of the certified organic farms that produce dry bulb onions in the USA are in the Great Lakes region, while onion thrips, Thrips tabaci Lindeman, and bulb-rot causing bacteria are important onion production constraints. Onion cultivars with semi-glossy foliage have been reported to support fewer thrips and suffer less thrips damage and therefore may provide a non-chemical option for thrips management. However, inconsistent results regarding efficacy of semi-glossy onions to reduce thrips densities have been reported in field studies. Bacteria causing bulb rot can infect onion plants through wounds in leaves, but the relationship between thrips damage and bacterial bulb rot disease needs further investigation. In this study, the performance of a semi-glossy onion hybrid, ‘USDA Maia’, was compared with the commonly grown waxy, thrips-susceptible cultivar ‘Bradley’ on certified organic farms in New York and Wisconsin from 2019 to 2021. Results indicated that thrips abundance was not different between ‘USDA Maia’ and ‘Bradley’. Bacterial bulb rot incidence in ‘USDA Maia’ was either similar or lower than the incidence in ‘Bradley’ in four of six trials, but higher in the other two. Marketable bulb yield in ‘USDA Maia’ was similar to yield in ‘Bradley’ in four of seven trials, but lower in the other three. Positive relationships between thrips density and bacterial bulb rot incidence occurred in one of three trials for both onion cultivars. Similarly, negative relationships between thrips density and marketable bulb yield only occurred in one of three trials, regardless of onion cultivar. ‘USDA Maia’ did not reduce thrips infestations as anticipated, but it was similar in susceptibility to bacterial bulb rot disease and produced similar large bulb yields as ‘Bradley’. While high thrips abundance can potentially increase incidence of bacterial bulb rot disease, wet growing conditions during bulbing was more important.
查看更多>>摘要：? 2022 Elsevier LtdThe use of insecticides is widespread for the management of insect pest populations. Injudicious use of insecticides is responsible for rapid development of resistance, environmental pollution and human health problems. Insecticide resistance is a great problem in managing insect pest populations of different crops using insecticides. The evolution of resistance may also affect other fitness parameters of resistant insects. In our study, the impact of imidacloprid resistance development on the fitness parameters of Oxycarenus hyalinipennis Costa (Hemiptera: Lygaeidae) and resistance stability was evaluated. After undergoing 19 generations of development selecting for resistance to imidacloprid, the imidacloprid selected (Imida-Sel) strain of O. hyalinipennis developed 55.30-fold and 146.50-fold resistance compared to UNSEL and susceptible strain, respectively. Imidacloprid resistance was found unstable and the resistant strain reverted towards susceptibility after cessation of insecticide selection pressure for eight generations. The value for Rf (relative fitness) was 0.41 for Imida-Sel with a significant reduction in mean relative growth rate (MRGR), intrinsic rate of natural increase (Rm) and net reproductive rate (Ro). Values of Rf for C1 and C2 were 0.85 and 0.77, respectively. The present study was designed to propose a comprehensive strategy for suppression of O. hyalinipennis. O. hyalinipennis exhibits potential for developing imidacloprid resistance, but the resistance was unstable and manageable with insecticide rotation. In addition, the fitness disadvantage associated with imidacloprid resistance may also slow down field evolution of imidacloprid resistance.
查看更多>>摘要：? 2022 Elsevier LtdThe indigenously prepared natural products namely; cow urine, Darekastra, fermented buttermilk, Panchgavya, Tamarlassi, vermiwash and biopesticide formulations i.e. Azadirachtin 0.15 EC and Eupatorium 5 EC possessing acaricidal activity were evaluated for their bioefficacy against Tetranychus urticae and their effects on cucumber fruit yield under protected environment. After 85 days of transplanting, preventive spray of bioacaricides, vermiwash (15.36 mites/leaf) and Darekastra (16.22 mites/leaf) resulted into lower mite population per leaf whereas curative spray of Darekastra significantly reduced mite population levels (112.53 mites/leaf). The effect of bioacaricide application in the form of spray was also quantified in terms of cucumber fruit yield. The bioacaricides applied as preventive sprays enhanced the cucumber fruit yield. High fruit yield was observed after preventive spray of bioacaricides viz. Tamarlassi (1660.67 g/plant), vermiwash (1656.50 g/plant) and Darekastra (1626.0 g/plant). As curative spray, Darekastra resulted into high fruit yield (1446.33 g/plant). Among the biopesticide checks, Azadirachtin 0.15 EC performed best in managing mite population levels and enhancing the fruit yield under both management measures.
查看更多>>摘要：? 2022 Elsevier LtdIn 2021, we observed symptoms of black mould disease on dates cv. Piarom, the most economically valuable export date cultivar in Hormozgan province, southern Iran. This study aimed to evaluate the disease incidence, identify the aetiological agent, and fulfill the pathogenicity on Piarom dates in this area. Aspergillus isolates were permanently obtained from the symptomatic dates on PDA, which were identified as Aspergillus niger based on morphological characteristics, as well as partial sequence data from the internal transcribed spacer region (ITS1-5.8S-ITS2) and Beta Tubulin (benA) gene. A phylogeny inferred using individual sequence data from ITS and benA sequences placed our isolates together with the other A. niger strains in the GenBank. The pathogenicity assays using symptom-free Piarom dates revealed the association of A. niger with the disease. Reisolation from the inoculated fruits yielded the isolates of A. niger, proving Koch's postulates. This is the first report of A. niger causing black mould disease on Piarom dates in Iran.
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