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1.
The gypsy moth (Lymantria dispar L., Lepidoptera: Lymantriidae) is one of the most serious pest of various forestal, food and industrial crops worldwide. We have characterized a new Lymantria dispar nucleopolyhedrovirus (LdMNPV-T4) variant, which was isolated from dead L. dispar larvae in Turkey. Scanning electron microscope observations showed that the polyhedral occlusion bodies (OBs) of the LdMNPV-T4 were irregularly shaped. Transmission electron microscopy revealed that OBs of LdMNPV-T4 were occupied with several virions in which multiple nucleocapsids packaged by viral envelope. Restriction analysis of the LdMNPV-T4 DNA purified from the viral inclusion bodies yielded BamHI, BglII, EcoRI and HindIII fragments. The mean size estimated for the complete LdMNPV-T4 genome was calculated to be 163.3 kb. Phylogenetic analysis of amplified polh, lef-8 and lef-9 sequences showed its relation to the other NPVs from Lymantria species. Mortality values of the LdMNPV-T4 at four different concentrations against third instar larvae of L. dispar ranged from 45% to 88%. These results suggest that LdMNPV-T4 isolated from Turkey is a promising microbial control agent to be utilized for the biological control of L. dispar.  相似文献   

2.
Dna J蛋白是Dna K/Hsp70的辅助分子伴侣,通过调节Hsp70的ATPase活性来影响蛋白复合体的合成与组装。为明确舞毒蛾Lymantria dispar的LdDnaJ1基因特性及对杀虫剂甲萘威的胁迫响应,通过克隆LdDnaJ1全长基因并运用实时荧光定量RT-PCR技术测定了甲萘威对其LdDnaJ1基因表达量的影响。结果表明,舞毒蛾Ld Dna J1全长基因开放阅读框为1 062 bp,编码353个氨基酸,分子质量为39.91 kD,理论等电点为5.65;舞毒蛾Dna J与柑橘凤蝶Papilio xuthus Dna J亲缘关系较近。甲萘威对舞毒蛾2龄幼虫24 h和48 h的致死中浓度LC50分别为74.04 mg/L和31.48mg/L。低剂量(LC_5、LC_(10)和LC_(30))甲萘威胁迫下,舞毒蛾2龄幼虫Ld Dna J1基因表达量均下调,LC_(30)甲萘威处理后72 h时LdDnaJ1基因表达量最低,仅为对照的15.70%。表明甲萘威可抑制舞毒蛾LdDnaJ1基因的表达,且呈现明显的时间和剂量效应。  相似文献   

3.
High antifeedancy and low toxicity of the plant preparation Neem (azadirachtin), on the gypsy moth, Lymantria dispar L. larvae were proved under laboratory conditions. A high index of Neem antifeedancy was confirmed in all tested concentrations.Under laboratory conditions the Neem had satisfying antifeedancy on Leptinotarsa decemlineata Say third instar larvae too. Field experiments also proved that the foliage protective effect of Neem was very significant.Experiments showed that some antifeedants or repellents, such as Neem, should control olygophagous (L. decemlineata, Coleoptera) insects as well as very polyphagous insects such as L. dispar (Lepidoptera).As a biological, plant-derived preparation, Neem could be suitable for integrated pest management (IPM) programs, especially in small orchards, parks, and tree rows in urban environments and on small private gardens.  相似文献   

4.
The spread of morning glory (Ipomoea spp.) in soybean fields in Japan has severely decreased soybean yield. Yet, current control measures do not control the proliferation of Ipomoea spp. As little is known about the flowering period and seed production among the different invading Ipomoea spp., it is challenging to create targeted control measures based on ecological characteristics. This study aimed to reveal the characteristics of the flowering phenology and seed production of four morning glory species, namely, Ipomoea coccinea L. (red morning glory), Ipomoea lacunosa L. (pitted morning glory), Ipomoea hederacea L. Jacq. var. integriuscula A. Gray (entireleaf morning glory), and Ipomoea triloba L. (three-lobe morning glory). Between 2017 and 2019, the four selected study species were grown under similar conditions of soil quality, irrigation, and environmental influences and their flowering phenology and seed data were recorded. The flowering period ranged from 36 to 40 days, and the initial flowering of I. triloba was approximately 2 weeks later than the others. I. coccinea had the highest flowering number and seed production, followed by I. lacunosa, I. triloba, and I. hederacea var. integriuscula. The fruit setting rate of I. triloba decreased later in the reproductive stage but tended to increase as the daily mean temperature increased on each flowering day. Thus, we report that the flowering phenology and seed production differed greatly among the Ipomoea spp. These findings can provide crucial insights into designing targeted species-specific control measures against the spread of Ipomoea spp. in Japan.  相似文献   

5.
Three cell lines of groundnut (Arachis hypogaea L), an important oilseed legume, were selected on glyphosate using in-vitro culture techniques. The cell lines isolated through single as well as stepwise selection procedures showed c 20-fold increase in glyphosate tolerance as compared to the unselected control cell line. Studies on the biochemical mechanism of glyphosate tolerance in these cell lines showed a significant increase in the total extractable activity of the target enzyme, 5-enolpyruvyl shikimate-3-phosphate (EPSP) synthase (EC 2.5.1.19), which was further confirmed with immunological data. The over-expressed EPSP synthase activity was, however, subject to inhibition by glyphosate in vitro. Two other key regulated enzymes of the shikimic acid pathway, 3-deoxy-D -arabino heptulosonate 7-phosphate (DAHP) synthase (EC 4.1.2.15) and chorismate mutase (CM) (EC 5.4.99.5) did not show any change in specific activity in the selected cell lines. The enhanced activity of EPSP synthase in the tolerant cell lines was found to be stably inherited in the absence of selection pressure. © 1999 Society of Chemical Industry  相似文献   

6.
Tomato (Solanum lycopersicum) is the second most important vegetable crop in the world. Bacterial spot (BS) of tomato, caused by four species of Xanthomonas: X. euvesicatoria, X. vesicatoria, X. perforans and X. gardneri, results in severe loss in yield and quality due to defoliation and formation of lesions on fruits, respectively. Currently management practices do not offer effective control under conditions of high disease pressure. Thus, developing BS resistance is a critical priority for tomato growers in order to minimize crop losses. Sixty‐three advanced tomato breeding lines, heirlooms and wild tomato lines with diverse genetic backgrounds were screened under greenhouse and field conditions for BS resistance using X. perforans race T4, which was found to be a prevalent race in North Carolina. Race T4 isolate 9 was used to inoculate the plants by spraying, and disease severity was measured using the Horsfall–Barratt scale. Tomato lines 74L‐1W(2008), NC2CELBR, 081‐12‐1X‐gsms, NC22L‐1 (2008) and 52LB‐1 showed resistance to BS in the field and/or greenhouse trials. These lines were derived from S. pimpinellifolium L3707. Screening L3707 followed by development of a mapping population and mapping resistance genes might be useful for breeding resistance against BS in future breeding programmes.  相似文献   

7.
氯苯醚酰胺[N-(2-(2,4-二氯苯氧基)苯基)-3-(二氟甲基)-1-甲基-1H-吡唑-4-酰胺,Y13149]是由华中师范大学基于药效团连接碎片虚拟筛选策略(PFVS)快速发现的新型琥珀酸脱氢酶抑制剂类(SDHIs)化合物。采用菌丝生长速率法,测定了该创制化合物的农药生物活性。结果表明:氯苯醚酰胺对真菌具有较广的抗菌谱,对供试10种植物病原真菌均具有较好的抑制活性,EC50值在0.008~15.25 mg/L之间,其对立枯丝核菌的抑制活性最强,但对辣椒疫霉和链状腐霉活性较弱。田间试验表明,氯苯醚酰胺对水稻纹枯病具有较好的防治效果,有效剂量75 g/hm2时的平均防效为79.6%,其防效总体略好于噻呋酰胺(75 g/hm2的平均防效为77.3%)。此外,氯苯醚酰胺对采自浙江和江苏两省的125株水稻纹枯病菌的EC50值分布在0.002~0.259 mg/L之间,且呈近似正态单峰曲线,平均EC50值为(0.021 ±0.008) mg/L,因此可将其作为水稻纹枯病菌对氯苯醚酰胺的敏感性基线,用于田间抗药性监测。  相似文献   

8.
为探究舞毒蛾控制和分泌滞育激素的器官，于室内对舞毒蛾幼虫的中枢神经系统进行显微解剖，对其中枢神经系统和咽下神经节进行观察，并测量舞毒蛾1~5龄幼虫咽下神经节长度、宽度和面积，运用共聚焦激光扫描显微镜对脑和咽下神经节玻片逐层扫描，获取舞毒蛾幼虫脑和咽下神经节各高度的图像，将扫描后的图片描绘成1组多边图形，将其导入软件中，软件将多边图形叠加后构建其三维模型。结果显示，舞毒蛾幼虫的中枢神经系统包括脑、咽下神经节、3个胸部神经节和7个腹部神经节；舞毒蛾不同龄期幼虫的咽下神经节在外观形态上无较大差异；随着龄期增长，舞毒蛾咽下神经节的长度、宽度以及面积也不断增加，其中4龄幼虫咽下神经节的长度、宽度以及面积的增长速度最快，而5龄幼虫咽下神经节的长度、宽度以及面积的增长速度略微下降，1~3龄幼虫咽下神经节的长度、宽度以及面积的增长速度大致相同，均小于4龄和5龄幼虫。通过测量外部形态结构重建了舞毒蛾脑和咽下神经节的三维模型。  相似文献   

9.
Scots pine trees (Pinus sylvestris) recovering from a 90–100% defoliation 2–3 years previously were pretreated with small mechanical wounds or inoculations with the blue-stain fungi Leptographium wingfieldii and Ophiostoma canum. Pretreated trees were less susceptible to a subsequent massive inoculation with L. wingfieldii than untreated control trees, which were extensively colonised by the mass-inoculation. A low pretreatment dosage of L. wingfieldii was somewhat more effective in inducing disease resistance than a higher dosage. Pretreatment with L. wingfieldii, O. canum, and mechanical wounding were about equally effective inducers of resistance in Scots pine, even though L. wingfieldii is known to produce much more extensive phloem necrosis than the other pretreatments. Thus, the strength of the induced resistance response did not depend on the amount of host tissues that was destroyed by the pretreatment. Previously, induced disease resistance has been demonstrated in Norway spruce (Picea abies), and the present study shows that similar responses can be activated in Scots pine.  相似文献   

10.
We assessed the seed production and shedding pattern of 10 common weed species in two oat fields in Denmark. The aim was to evaluate the possibility of harvesting retained seeds on weeds at crop harvest by a combine harvester based on estimation of weed seed retention. Before flowering, ten plants of each weed species were selected and surrounded by a seed trap comprising of a porous net. When the plants started shedding seeds, the seeds were collected from the traps and counted weekly until oat harvest. Just before oat harvest, the retained seeds on the plants were counted and the ratio of harvestable seeds and shed seeds during the growing season was determined. The seed production and shedding patterns varied between the 2 years. Across both years, Anagallis arvensis L., Capsella bursa-pastoris L. Medik, Chenopodium album L., Geranium molle L., Persicaria maculosa Gray, Polygonum aviculare L., Silene noctiflora L., Sonchus arvensis L., Veronica persica Poir. and Viola arvensis Murray retained on average 61.6%, 52.7%, 67.2%, 58.4%, 32.05%, 59.5%, 95.7%, 23.5%, 51.7% and 33.9%, respectively, of their produced seeds at crop harvest. Silene noctiflora was classified as a good target for harvest weed seed control; C. bursa-pastoris, C. album, G. molle, P. maculosa, S. arvensis and V. arvensis were classified as intermediate targets; and A. arvensis, P. aviculare and V. persica were classified as poor targets.  相似文献   

11.
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12.
A monoclonal antibody (McAb), 4B8, was developed to whole homogenates of the brown planthopper, Nilaparvata lugens (Stål), using hybridoma technology. It reacted with all the stages of BPH but did not cross-react with other insects and predator species tested with an indirect enzyme-linked immunosorbent assay (ELISA). Immunodiffusion revealed it to belong to the IgG3 subclass. The ascites developed with 4B8?cell lines had high absorbance values until it was diluted over 6.5536?×?107 times tested by indirect ELISA. It could recognize the BPH proteins after one female was ingested by Pardosa pseudoannulata for about 2.13 days at 25°C. The results of extended antigen detection period and the high specificity of the antibody indicated that 4B8 could be used to study interactions between planthoppers and their predators in the field. Application of the McAb to assess relative importance of four major spider species in subtropical rice ecosystem showed that P. pseudoannulata was more important than Ummeliata insecticeps, and those were more important than Tetragnatha sp. and Coleosoma octomaculatum.  相似文献   

13.
Phytophthora root and stem rot of soybean caused by Phytophthora sojae is a destructive disease affecting soybean production worldwide. In nature, soybean is the only economically important cultivated host of P. sojae. The aim of this study was to explain different resistance mechanisms to P. sojae in nonhost common bean and host soybean as a basis for the control of Phytophthora root and stem rot of soybean via nonhost resistance. Observations and measurements of disease resistance-related variables showed slight differences in structural and biochemical resistance mechanisms between common bean and soybean. P. sojae infection induced a stronger hypersensitive response in nonhost common bean than in host resistant soybean. Moreover, phytoalexin phaseollidin synthesis-related vestitone reductase gene was extremely highly up-regulated, and phytoalexin glyceollin synthesis-related isoflavone reductase gene was slightly less up-regulated in common bean than in soybean, which resulted in a higher level of phaseollidin and a lower level of glyceollin in common bean. Phaseollidin had stronger inhibitory effects on mycelial growth and oospore formation of P. sojae than glyceollin, and more cell wall depositions and callose accumulated in common bean, which are probably related to the stronger resistance of nonhost common bean to P. sojae.  相似文献   

14.
The phagostimulatory response of the larvae of the gypsy moth,Porthetria dispar, to ethanolic-aqueous extracts of the leaf powder of different host and non-host plants, was assayed in no-choice experiments using the Styropor® method.Quercus robur L. was the most active at all concentrations tested;Picea excelsa Link, was highly active only at 4%;Pyrus malus L. showed an intermediate activity at 4%; and very slight or no feeding occurred with the extracts ofPinus silvestris L.,Ilex aquifolium L. andTaxus baccata L. The phagodeterrent effect of thePinus silvestris andIlex aquifolium extracts was demonstrated by treating the lamellae with a mixture of each one of them with the highly phagostimulatory extract ofQ. robur. The following monoterpenes tested were highly phagodeterrent at 0.2%: α-pinene, β-pinene, 3-carene; camphene was totally deterrent even at 0.05%, whereas limonene was not phagodeterrent even at 0.2%. Among other substances coumarin and lactic acid were active at 0.2%, whereas citric acid, oxalic acid and tannic acid were not phagodeterrent even at 0.2%.  相似文献   

15.
Root rot of cocoyam (Xanthosoma sagittifolium) caused by Pythium myriotylum is the most devastating disease of this important tropical tuber crop with yield reductions of up to 90%. Bioassays were conducted in vitro and in sterile volcanic soil artificially infested with Pythium myriotylum, isolate CRPm, to test whether Pseudomonas aeruginosa PNA1 can control the cocoyam root rot disease. P. aeruginosa PNA1 (wild type) produces phenazine-1-carboxylic acid and phenazine-1-carboxamide (oxychlororaphin), while its tryptophan auxotrophic mutant FM13 is phenazine negative and secretes anthranilate in vitro. PNA1 and FM13 have previously been shown to control Pythium debaryanum and Pythium splendens on lettuce and bean. PNA1 and FM13 significantly inhibited growth of P. myriotylum in dual cultures, while their supernatants highly reduced mycelial dry weight in potato dextrose broth. However, in the presence of tissue culture derived cocoyam plantlets, only strain PNA1 strongly reduced root rot disease severity. Soil experiments involving strain PNA1 in comparison to phenazine-deficient mutants suggested that the biocontrol activity of PNA1 against P. myriotylum may involve phenazines. Phenazine involvement was further strengthened by the fact that FM13 fed with exogenous tryptophan (so that phenazine production is restored) significantly reduced disease severity on cocoyam. The efficiency of PNA1 to control P. myriotylum on cocoyam was significantly improved when the strain and the pathogen were allowed to interact for 24 h prior to transplanting cocoyam plantlets, while doubling the inoculum density of the pathogen negatively affected its efficiency.  相似文献   

16.
Sunflower chlorotic mottle virus (SuCMoV) is a recently described potyvirus that causes systemic infections in sunflower plants leading to chlorotic mottling and important growth reductions and yield losses. Oxidative damage is expressed after symptom development in this host-pathogen combination. The involvement of antioxidant enzyme activities in disease susceptibility was studied in two sunflower lines differing in the intensity and rate of development of SuCMoV infections: L2 is more susceptible than L33. A transient superoxide production peak was detected in leaves of both lines before symptom development. H2O2 accumulation increased before symptom expression in infected plants of L33 but in L2 such increase was registered only after symptoms became evident. In healthy plants of both lines, superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) showed similar activity levels. In inoculated plants of line L2, but not in L33, SOD and CAT activities increased significantly before the appearance of symptoms, and APX increases were detected later. A 1 mM SA treatment effectively decreased SuCMoV accumulation in plants of L2 but it did not affect it in L33. This treatment increased H2O2 accumulation and prevented the increase in antioxidant enzyme activities in infected plants of L2. It is suggested that increases in antioxidant enzyme activities interrupted the signals generated by the increase in ROS, which may have otherwise triggered defence reactions in the host and thus, resulted in a compatible interaction.  相似文献   

17.
Azoxystrobin was recently registered in Japan for the control of purple seed stain of soybean caused by Cercospora kikuchii, because the pathogen has developed resistance to thiophanate-methyl. To investigate the effects of these fungicides on the frequency of C. kikuchii strains resistant to thiophanate-methyl and on the genotype structure of the population, we sowed purple-stained seeds, approximately 40% of which were infected with resistant strains, as inocula with asymptomatic seeds and applied thiophanate-methyl and azoxystrobin during the reproductive growth of soybeans. The isolation frequency of resistant strains increased more than 99% by thiophanate-methyl but was not significantly increased by azoxystrobin. In amplified fragment length polymorphism (AFLP) DNA fingerprinting, genotypic diversity was significantly decreased by thiophanate-methyl but was not affected by azoxystrobin. In addition, the similarity of the AFLP genotype structure was increased by thiophanate-methyl but not by azoxystrobin. These results suggest that thiophanate-methyl selectively inhibited the proliferation of sensitive strains, which resulted in a small number of genotypes, most of which were resistant strains. Azoxystrobin was found to nonselectively inhibit proliferation of the pathogen, which retained a large number of genotypes including thiophanate-methyl-sensitive or thiophanate-methyl-resistant strains or both. The nucleotide sequence data for the cytochrome b gene are available in the DDBJ/EMBL/GenBank databases under accession number AB231863.  相似文献   

18.
Development of integrated weed management strategies is dependent on a thorough knowledge of the demography of individual species. The current research established eight winter or summer weed species in a winter annual wheat cropping system at Wongan Hills, Western Australia, and investigated emergence of the first cohort of each species, survivorship, plant size, seed production and seed shedding over three years (2016–2019). The winter weeds Bromus diandrus and Lolium rigidum emerged at the same time as the wheat crop, and the initial cohort of marked plants had 100% survival to seed production in each year. By comparison, other winter weed species like Hordeum leporinum, Rumex hypogaeus, Sonchus oleraceus and Polygonum aviculare frequently emerged later than the crop and had a lower percentage of plants surviving to seed production. However, individual S. oleraceus and P. aviculare plants had the greatest seed production compared to other species. All winter weeds had variable patterns of seed shedding between years, with the exception of L. rigidum. Summer weed species emerged at the same time, but plants in the initial cohort of each species did not always survive to produce seed. The early emergence and high survivorship of B. diandrus indicates high competitive ability, but shedding commenced at a similar time to L. rigidum and harvest weed seed control may be a viable control method for this species.  相似文献   

19.
Several species of ambrosia beetles (Coleoptera: Scolytidae) have recently started attacking standing, living beeches (Fagus sylvatica) in southern Belgium. In 2001, 1.3 million m3 of apparently healthy trees were struck. So far the outbreak has been limited to the Ardenne, and partly the Gaume, areas, and Brussels has been untouched. The city of Brussels is surrounded by a vast 4300 ha forest, mainly planted with beech, the Forêt de Soignes, of invaluable ecological and recreational value, of which 1600 ha belong to the regional authorities. In the spring 2001, these latter commissionned a study to assess the new threat to the forest. A 500 m×500 m grid of small traps, baited with ethanol and lineatin, was deployed over the regional part of the forest. The main species caught were Trypodendron domesticum, Anisandrus dispar and, in high numbers, Xylosandrus germanus, an exotic species of Asian origin found for the first time in Belgium in 1994. Whilst there was a consistent homogeneity between catches within the same sites (2 traps/site, distant by 2–6 m), there were no spatial relationships between catches at larger distances for T. domesticum and A. dispar. For X. germanus, spatial autocorrelations were observed within distances of 2000 m, suggesting that this species has sufficient mobility to cover this range. The planning of the 2002 trapping campaign will take this information into account: the traps will be deployed within a smaller grid.  相似文献   

20.
Control of grey mould, caused by Botrytis spp., is a major challenge in open field strawberry production. Botrytis was isolated from plant parts collected from 19 perennial strawberry fields with suspected fungicide resistance in the Agder region of Norway in 2016. Resistance to boscalid, pyraclostrobin and fenhexamid was high and found in 89.1%, 86.0% and 65.4% of conidia samples, respectively. Multiple fungicide resistance was common; 69.6% of conidia samples exhibited resistance to three or more fungicides. Botrytis group S and B. cinerea sensu stricto isolates were obtained from 19 and 16 fields, respectively. The sdhB, cytb, erg27 and mrr1 genes of a selection of isolates were examined for the presence of mutations known to confer fungicide resistance to boscalid, pyraclostrobin, fenhexamid and pyrimethanil plus fludioxonil, respectively. Allele-specific PCR assays were developed for efficient detection of resistance-conferring mutations in cytb. Among B. cinerea isolates, 84.7%, 86.3% and 61.3% had resistance-conferring mutations in sdhB, cytb and erg27, respectively. A triplet deletion in mrr1, resulting in ΔL497, commonly associated with the multidrug resistance phenotype MDR1h, was detected in 29.2% of Botrytis group S isolates. High frequencies of resistance to several fungicides were also detected in Botrytis from both imported and domestically produced strawberry transplants. Fungicide resistance frequencies were not different among fields grouped by level of grey mould problem assessed by growers, indicating factors other than fungicide resistance contributed to control failure, a fact that has important implications for future management of grey mould.  相似文献   

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