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1.
The apple rust mite Aculus schlechtendali (Nal.) (Acari: Eriophyidae), is a main pest in apple-growing areas in Ankara, Turkey, and chemical control applications have some limitations. Entomopathogenic fungi have a potential for biological control of mites. In this study, an entomopathogenic fungus, Paecilomyces lilacinus (Thom) Samson (Deuteromycota: Hyphomycetes), was first isolated from the mite cadavers on Japanese crab apple leaves and pathogenicity of the fungus was observed in different inoculum densities and relative humidities. The pathogen caused up to 98.22% mortality of the mite population. The effects of some fungicides on the entomopathogenic fungus were determined in in vitro studies. Carbendazim, penconazole and tebuconazole were the most effective fungicides on mycelial growth of P. lilacinus, with EC50 values under 3 μg ml−1. In spore germination tests, captan, mancozeb, propineb were the most effective fungicides, followed by tebuconazole, penconazole, nuarimol and chlorothalonil. Sulphur could not inhibit the conidia germination totally at 5,000 μg ml−1. Copper oxychloride and fosetyl-al prevented conidia formation at concentrations above 1,000 μg ml−1.  相似文献   

2.
The greater wax moth Galleria mellonella L. (Lepidoptera: Pyralidae) is occasionally found in beehives and is a major pest of stored wax. Entomopathogenic fungi have recently received attention as possible biocontrol elements for certain insect pests. In this study, 90 isolates of Beauveria bassiana and 15 isolates of Metarhizium anisopliae were screened for proteases and lipases production. The results showed significant variations in the enzymatic action between the isolates. In the bioassay, the selected isolates evinced high virulence against the 4th instar of the G. mellonella larvae. The isolates BbaAUMC3076, BbaAUMC3263 and ManAUMC3085 realized 100% mortality at concentrations of 5.5 × 106 conidia ml−1, 5.86 × 105 conidia ml−1, and 4.8 × 106 conidia ml−1, respectively. Strong enzymatic activities in vitro did not necessarily indicate high virulence against the tested insect pest. The cuticle of the infected larvae became dark and black-spotted, indicating direct attack of fungus on the defense system of the insects. The LC50 values were 1.43 × 103, 1.04 × 105 and 5.06 × 104 for Bba3263AUMC, Bba3076AUMC and Man3085AUMC, respectively, and their slopes were determined by computerized probit analysis program as 0.738 ± 0.008, 0.635 ± 0.007 and 1.120 ± 0.024, respectively.  相似文献   

3.
Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is an exotic species native to the USA, damaging cotton and other plant families. The feeding potential of different development stages of Cryptolaemus montrouzieri Mulsant, a biological control agent against mealybugs, was investigated on different development stages of P. solenopsis. Fourth instar grubs and adults of C. montrouzieri were the most voracious feeders on different instars of mealybug. The number of 1st instar nymphs of mealybug consumed by 1st, 2nd, 3rd and 4th instar larvae and adult beetles of C. montrouzieri was 15.56, 41.01, 125.38, 162.69 and 1613.81, respectively. The respective numbers of 2nd and 3rd instar nymphs of mealybug consumed were 11.15 and 1.80, 26.35 and 6.36, 73.66 and 13.32, 76.04 and 21.16, 787.95 and 114.66. The corresponding figures for adult female mealybugs were 0.94, 3.23, 8.47, 12.71 and 73.40, respectively. The results indicate that C. montrouzieri has the potential to be exploited as a biocontrol agent in North India; inoculative releases of 4th instar larvae and adults may provide instant control of P. solenopsis. Field experiments should be conducted to determine the efficiency of the ladybird on this mealybug.  相似文献   

4.
Susceptibility of eggs of Tribolium confusum du Val. (Coleoptera: Tenebrionidae), Ephestia kuehniella (Zell.) (Lepidoptera: Phycitidae) and Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) to vapors of essential oil from garlic (Allium sativum L.), birch (Betula lenta L.), cinnamon (Cinnamonum zeylanicum (Blume)) and aniseed (Pimpinella anisum L.) was studied. Preliminary bioassay tests indicated that vapors of the essential oils had a significant effect on the eggs of tested insect species when exposed to a concentration of 20 μl l −1 air for 24 h. Generally, garlic and birch essential oils were more toxic to the eggs of tested insect species than cinnamon and aniseed essential oils (except for eggs of T. confusum). There was also a significant difference between susceptibility of eggs of T. confusum, E. kuehniella and P. interpunctella to tested essential oils. Toxicity data indicated that eggs of T. confusum were more susceptible to tested essential oils, with LC90 values ranging from 3.11 to 33.49 μl l −1 air, than those of E. kuehniella and P. interpunctella; eggs of P. interpunctella were the most tolerant to the essential oils, with LC90 values ranging from 22.02 to 72.42 μl l −1 air. Concentration × time (Ct) products of 0.29, 0.22, 0.13 and 1.37 mg h l −1 for garlic, birch, cinnamon and aniseed essential oil, respectively, were required to obtain 90% kill of T. confusum eggs. Although cinnamon essential oil had a much closer Ct product value to methyl bromide, garlic and birch essential oils were found to be the most promising ones since they had also high fumigant toxicity on eggs of both E. kuehniella and P. interpunctella.  相似文献   

5.
In August 2009, boring lepidopteran larvae were found on aerial parts of tomato (Lycopersicon esculentum Mill.) plants in the Urla District of Izmir Province within the Aegean Region of Turkey. Larvae created blotched leaf galleries and superficial mines on fruits. The pest was identified as Tuta absoluta (Meyrick 1917) (Lepidoptera: Gelechiidae). This is the first report of this pest in Turkey.  相似文献   

6.
The efficacy of a seed treatment of oilseed rape (OSR) (Brassica napus) with the rhizobacteria Serratia plymuthica (strain HRO-C48) and Pseudomonas chlororaphis (strain MA 342) applied alone or in combination against the blackleg disease caused by Leptosphaeria maculans was tested with different cultivars. Seeds were soaked in bacterial suspensions (bio-priming) to obtain log10 6–7 CFU seed−1. Cotyledons were inoculated with a 10 ul droplet of L. maculans spore suspension of log10 7 spores ml−1 and the disease index (size of lesions) was evaluated 14 days later. A mean disease reduction of 71.6% was recorded for S. plymuthica and of 54% for P. chlororaphis. The combined treatment was not superior to the treatment with S. plymuthica alone. The reduction of the disease caused by S. plymuthica was independent of the cultivar’s susceptibility, whereas the control effect recorded with P. chlororaphis increased with decreasing cultivar resistance to blackleg disease. The bacterial colonization of OSR was restricted to the roots and hypocotyl. No significant difference in bacterial colonization of the rhizosphere was observed between different cultivars, nor between single or combined bacterial seed treatments.  相似文献   

7.
Wasabi (Wasabia japonica) is grown for its highly-valued rhizome which is used as a condiment in Japanese food. Symptoms of vascular blackening in the rhizome were first observed in 2005 in plants grown in British Columbia, Canada. Microscopic observations and microbial isolation from infected tissues revealed that most of the xylem tracheid cells were blackened and bacteria were consistently associated with symptomatic plants. The bacterium most frequently recovered was identified as Pectobacterium carotovorum subsp. carotovorum (Pcc) using BioLog™ and sequencing of a specific ~510 bp IGS region. Pathogen-free plants obtained using meristem-tip micropropagation were inoculated with a wasabi isolate of Pcc. Vascular blackening symptoms developed in the rhizome after 8 weeks when the rhizome was first wounded by stabbing or cutting, or if the roots were pre-inoculated with Pythium species isolated from rhizome epidermal tissues, followed by inoculation with Pcc at 1 × 108 cells ml−1. Xylem tracheid cells were blackened and Pcc was reisolated from all diseased tissues. The highest frequency of rhizome vascular blackening occurred at 22°C and 27°C and these tissues occasionally succumbed to soft rot at higher temperatures, but not when inoculated tissues were incubated at 10°C. The rooting medium used by growers for vegetative propagation of wasabi was shown to contain Pcc but the pathogen was not recovered from the irrigation water. Entry of Pcc through wounds on wasabi rhizomes and the host tissue response result in symptoms of vascular blackening.  相似文献   

8.
Sclerotinia sclerotiorum is a worldwide ascomycete fungal plant pathogen, which causes enormous yield losses on major economic crops such as crucifers, grain legumes and several other plant families. The objective of this research was to isolate and characterise some bioactive products from cultures of fungi associated with the marine sponge Axinella sp. In total, nine fungal isolates were obtained from the marine sponge Axinella sp. collected from the South China Sea. A group of test strains, including two G+ strains (Bacillus subtilis and Staphylococcus aureus), two G− strains (Escherichia coli and Pseudomonas aeruginosa) and three fungi including two plant pathogenic fungi Sclerotinia sclerotiorum and Magnaporthe grisea and Saccharomyces cerevisiae, were employed as the indicator organisms for bioactivity screening. Using antagonistic tests and bioactive screening of the ethyl acetate (EtOAc) extracts of the corresponding cultures, fungal isolate JS9 showed the stronger efficacy against the test indicator strains, especially the indicator fungal pathogens. Isolate JS9 was further identified as Myrothecium sp. by a combination of morphological features and 18S rDNA BLAST on GenBank. Two macrocyclic trichothecenes, roridin A (compound 1) and roridin D (compound 2) were purified by tracking the activity of the EtOAc extract fractions and characterised with spectral analyses including MS, 1H-NMR, 13C-NMR and disortionless enhancement by polarization transfer (DEPT). In vitro antifungal tests showed that the two macrocyclic trichothecenes were bioactive against S. cerevisiae, M. grisea and S. sclerotiorum with minimal inhibitory concentrations of 31.25, 125 and 31.25 μg ml−1 for roridin A, and 62.5, 250 and 31.25 μg ml−1 for roridin D, respectively. The present investigation demonstrated that two antifungal trichothecenes including roridin A and roridin D produced by the fungus Myrothecium sp. isolated from the marine sponge Axinella sp. could be potential inhibitors against the plant pathogen S. sclerotiorum. Lian Wu Xie and Shu Mei Jiang contributed equally to this work.  相似文献   

9.
The pathogenicity and reproductive fitness of Pratylenchus coffeae and Radopholus arabocoffeae from Vietnam on coffee (Coffea arabica) seedlings cv. Catimor were evaluated in greenhouse experiments. The effect of initial population densities (Pi = 0, 1, 2, 4, 8, 16, 32, 64, 128, and 256 nematodes per cm3 soil) was studied for both species at different days after inoculation (dai). The data were adjusted to the Seinhorst damage model Y = m + (1-m).zPi-T. Tolerance limit (T) for P. coffeae was zero for the height and the diameter of the coffee plants. For the diameter, the T-value for R. arabocoffeae was 25.6 for 30 and 60 dai and 12.8 for 90 and 120 dai. After 4 months T was zero. The low tolerance limits indicate that Arabica coffee is highly intolerant to both nematode species. At the end of the experiment (180 dai), all plants were infected and most were dead when inoculated with R. arabocoffeae at initial densities of 32, 64, 128 and 256 nematodes/cm3 soil. For P. coffeae plant death was already observed at the lowest inoculation densities. Growth of coffee was reduced at all inoculation levels for both species. Pratylenchus coffeae and R. arabocoffeae caused intense darkening of the roots, leaf chlorosis and a strong reduction of root and shoot growth. It was observed that P. coffeae mainly destroyed lateral roots rather than tap roots, whereas R. arabocoffeae reduced tap root length rather than the lateral roots. At the lowest inoculum densities, the reproduction factor of P. coffeae was 2.38 and 2.01 for R. arabocoffeae, indicating that arabica coffee is a host for both species. Plant growth as expressed by shoot height and shoot and root weight measured 60 dai was negatively correlated with nematode (both species) density as expressed by the geometric mean of nematode numbers at 30 and 60 dai.  相似文献   

10.
Colletotrichum isolates isolated from cowpea in the Hangzhou area of China were identified as C. destructivum based on morphological characteristics, pathogenicity tests, sequence analysis of the internal transcribed spacer (ITS)1, 5.8S RNA gene and ITS2 regions of ribosomal DNA and the infection process. The ability of the C. destructivum isolates to infect Arabidopsis thaliana was investigated under laboratory conditions and showed a two-phase hemibiotrophic infection process. In addition, the sequences of the rDNA ITS region of C. destructivum isolates from cowpea were identical with 100% similarity to that of isolates of C. higginsianum originating from cruciferous plants. This article presents new evidence in support of C. higginsianum as a synonym of C. destructivum.  相似文献   

11.
The tomato pathotype of Alternaria alternata (A. arborescens) produces the dark brown to black pigment melanin, which accumulates in the cell walls of hyphae and conidia. Melanin has been implicated as a pathogenicity factor in some phytopathogenic fungi. Here, two genes of the tomato pathotype for melanin biosynthesis, ALM1 and BRM2-1, which encode a polyketide synthetase and a 1,3,8-trihydroxynaphthalene (THN) reductase, respectively, have been cloned and disrupted in the pathogen. The gene-disrupted mutants, alm1 and brm2-1, had albino and brown phenotypes, respectively. The wild-type and the mutants caused the same necrotic lesions on the leaves after inoculation with spores. These results suggest that melanin is unlikely to play a direct role in pathogenicity in the tomato pathotype A. alternata. Scanning electron microscopy revealed that the conidia of both mutants have much smoother surfaces in comparison to the wild-type. The conidia of those mutants were more sensitive to UV light than those of the wild-type, demonstrating that melanin confers UV tolerance.  相似文献   

12.
The location of Pepper mild mottle virus (PMMoV) within seeds as they developed on inoculated seedlings of pepper (Capsicum annuum) was followed over time by detecting the viral coat protein using immunofluorescence microscopy. Seedlings were inoculated with PMMoV when the flower buds on the first and second branching nodes were in bloom. Fluorescence indicating the presence of PMMoV was first observed around immature seeds and placentas in the ovaries on the fourth branching node at 20 days post-anthesis (20 DPA), which corresponded to 39 days post-inoculation (39 DPI). The area with fluorescence gradually expanded from the placenta into the integument and the parenchyma, and finally reached the tip of the immature seeds by 34 DPA (53 DPI). The embryo or endosperm beyond the endothelium never fluoresced during the experiment [i.e., ending at 81 DPA (102 DPI)]. For visualizing viral routes of invasion from seeds into new seedlings, PMMoV-infected C. annuum seeds that were heterozygous for the L 3 tobamovirus-resistance gene were sown in soil at 30°C. After ~2 weeks, the cotyledon developed virally induced necrosis. These findings shed light on the infection cycle of PMMoV through vertical transmission in C. annuum.  相似文献   

13.
The predatory insect Anthocoris minki Dohrn (Heteroptera: Anthocoridae) is an indigenous Anthocoris species for the biological control of pests in pistachio orchards. The pistachio psylla Agonoscena pistaciae Burckhardt and Lauterer (Homoptera: Psyllidae) is an important insect pest in pistachio trees in Turkey. Similarly, Brachycaudus (Thuleaphis) amygdalinus (Schouteden) (Hemiptera: Aphididae) is a pest of almond trees that is considered as alternative prey for A. minki when pistachio psylla are not available in early spring on pistachio trees. The development time, survival percentage of immature stages, longevity, fecundity, prey consumption, and life table parameters of A. minki fed on A. pistaciae and B. amygdalinus nymphs were determined at 25 ± 1°C, 70 ± 5% r.h., and a 16 h:8 h (L:D) photoperiod under laboratory conditions. The nymphal survival rate was significantly higher when nymphs were fed on A. pistaciae (an average of 96.7%) than on B. amygdalinus (an average of 71.4%). The development time of A. minki was significantly shorter when nymphs were fed on B. amygdalinus (10.3 days) as opposed to A. pistaciae (11.0 days). No significant differences among prey species were found for longevity and fecundity. The total female longevity and fecundity of A. minki was 38.0 days and 247.2 eggs, respectively, when nymphs were fed on A. pistaciae; and 35.4 days and 233.0 eggs, respectively, when nymphs were fed on B. amygdalinus. On average, 104.4 A. pistaciae and 77.7 B. amygdalinus nymphs were consumed during the nymphal development time for A. minki. Adults of A. minki consumed significantly more psyllids than aphids throughout their life span. The greater difference did not significantly inpact the longevity and fecundity of A. minki. Females of A. minki consumed an average of 631.0 A. pistaciae and an average of 273.3 B. amygdalinus nymphs, while female predators consumed significantly more prey than males. The intrinsic rate of increase (r m ) of A. minki fed on A. pistaciae (0.174) was significantly greater than those fed on B. amygdalinus (0.148). The successful development and reproduction of both A. pistaciae and B. amygdalinus indicates that they are suitable prey for A. minki.  相似文献   

14.
Random insertional mutagenesis using a marker DNA fragment is an effective method for identifying fungal genes relevant to morphogenesis, metabolism, and so on. Agrobacterium tumefaciens-mediated transformation (AtMT) has long been used as a tool for the genetic modification of a wide range of plant species. Recent study has indicated that A. tumefaciens could transfer T-DNA not only to plant cells but also to fungal cells. In this study, AtMT was applied to Colletotrichum lagenarium for random insertional mutagenesis. We constructed a binary vector pBIG2RHPH2 carrying a hygromycin-resistant gene cassette between the right and left borders of T-DNA. Optimal co-cultivation of C. lagenarium wild-type 104-T with pBIG2RHPH2-introduced A. tumefaciens C58C1 led to the production of 150–300 hygromycin-resistant transformants per 106 conidia. Southern blot analysis revealed that T-DNA was mainly integrated at a single site in the genome and at different sites in transformants. The T-DNA inserts showed small truncations of either end, but the hygromycin-resistant gene cassette inside the T-DNA was generally intact. The mode of T-DNA insertion described above resulted in highly efficient gene recovery from the transformants by thermal asymmetrical interlaced-polymerase chain reaction. The fungal genomic DNA segments flanking T-DNA were identified from five of eight mutants that had defective melanin biosynthesis. The sequence from one of the segments was identical to that of the melanin biosynthesis gene PKS1 of C. lagenarium, which we previously characterized. These results strongly support our notion that AtMT is a possible tool for tagging genes relevant to pathogenicity in the plant pathogenic fungus C. lagenarium.  相似文献   

15.
Virus-like symptoms—red ringspots on stems and leaves, circular blotches or pale spots on fruit—were found on commercial highbush blueberry (Vaccinium corymbosum) cultivars Blueray, Weymouth, Duke and Sierra in Japan. In PCR testing, single DNA fragments were amplified from total nucleic acid samples of the diseased blueberry bushes using primers specific to Blueberry red ringspot virus (BRRV). Sequencing analysis of the amplified products revealed 95.7–97.7% nucleotide sequence identity with the BRRV genome. This paper is the first report of blueberry red ringspot disease caused by BRRV in Japan. The nucleotide sequence data reported in this paper are available in the GenBank/EMBL/DDBJ database as accessions AB469884 to AB469893 for BRRV isolates from Japan.  相似文献   

16.
Xanthomonas oryzae pv. oryzicola, the causal agent of rice leaf streak disease, was found to be sensitive to streptomycin (an aminocyclitol glycoside antibiotic), by inhibition of protein synthesis resulting from interference with translational proofreading. This study aimed to determine the molecular resistance mechanism of X. oryzae pv. oryzicola to streptomycin. Seven streptomycin-resistant mutants were obtained by UV induction or streptomycin selection. These mutants can grow at 100 μg ml−1 of streptomycin while the wild-type strain (RS105) cannot grow at 5 μg ml−1. Sequencing indicated that the rpsL gene encoding ribosomal protein S12 has 375 bp encoding 125 amino acid residues. In all resistant strains, a mutation in which AAG was substituted for AGG (Lys→Arg) occurred either at codon 43 or 88. Two plasmids, pUFRRS and pUFRRX, were constructed by ligating the rpsL gene into the cosmid pUFR034. The plasmids pUFRRS and pUFRRX containing the Lys→Arg mutation of the rpsL gene conferred streptomycin resistance to the sensitive wild-type strain by electroporation. Both transformants, RS1 and RS2, could grow in the medium containing 50 μg ml−1 of streptomycin. A mutation at codon 43 or 88 in rpsL can result in resistance of Xanthomonas oryzae pv. oryzicola to streptomycin.  相似文献   

17.
Mycosphaerella leaf disease (MLD) is caused by species of Mycosphaerella and several anamorphic form genera that have been connected to Mycosphaerella. Until recently, MLD of eucalypts was largely ignored in Portugal. However, serious damage to Eucalyptus globulus has been reported since 1999 when frequent and severe defoliation of young trees was observed. The severity of this disease prompted a preliminary study of the Mycosphaerella species associated with major symptoms of a leaf blotch disease in commercial plantations of E. globulus in Portugal, which is presented here. The species were identified by molecular methods based on the ITS1-5.8S-ITS2 cluster, together with morphological characters. In addition to confirming the species previously recorded, Mycosphaerella vespa is reported for the first time from Portugal, while the status of Mycosphaerella grandis remains to be resolved.  相似文献   

18.
Yeast-like fungi were isolated from lesions on azuki bean (cv. Shin-Kyotodainagon) seeds that had been sucked by bean bugs in Kyoto Prefecture, Japan. On the basis of morphological and physiological characteristics and sequence data of the internal transcribed spacer (ITS) regions including the 5.8S rDNA, these yeasts were identified as Eremothecium coryli and E. ashbyi. Pathogenicity of those yeasts was confirmed by a reinoculation test. To our knowledge, this is the first report of the occurrence of yeast spot in azuki bean in Japan. The nucleotide sequence data reported are available in the GeneBank/EMBL/DDBJ database as accessions AB478291–AB478309 for E. coryli AZC1–19 and AB478310–AB478317 for E. ashbyi AZA1–8.  相似文献   

19.
In a field experiment between 2004 and 2006, 14 winter wheat varieties were inoculated with either a mixture of three isolates of F. poae or a mixture of three isolates of F. avenaceum. In a subsequent climate chamber experiment, the wheat variety Apogee was inoculated with individual single conidium isolates derived from the original poly conidium isolates used in the field. Disease symptoms on wheat heads were visually assessed, and the yield as well as the fungal incidence on harvested grains (field only) was determined. Furthermore, grains were analysed using LC-MS/MS to determine the content of Fusarium mycotoxins. In samples from field and climate chamber experiments, 60 to 4,860 μg kg−1 nivalenol and 2,400 to 17,000 μg kg−1 moniliformin were detected in grains infected with F. poae and F. avenaceum, respectively. Overall, isolate mixtures and individual isolates of F. avenaceum proved to be more pathogenic than those of F. poae, leading to a higher disease level, yield reductions up to 25%, and greater toxin contamination. For F. poae, all variables except for yield were strongly influenced by variety (field) and by isolate (climate chamber). For F. avenaceum, variety had a strong effect on all variables, but isolate effects on visual disease were not reflected in toxin production. Correlations between visual symptoms, fungal incidence, and toxin accumulation in grains are discussed.  相似文献   

20.
The clustered hrp genes encoding the type III secretion system in the Japanese strains MAFF301237 and MAFF311018 of Xanthomonas oryzae pv. oryzae were sequenced and compared. The strains differ in their pathogenicity, location, and year of isolation. A 30-kbp sequence comprising 29 open reading frames (ORFs) was identical in its structural arrangement in both strains but differed from X. campestris pv. campestris, X. axonopodis pv. citri, and X. axonopodis pv. glycines in certain genes located between the hpaB-hrpF interspace region. The DNA sequence and the putative amino acid sequence in each ORF was also identical in both X. oryzae pv. oryzae strains as were the PIP boxes and the relative sequences. These facts clearly showed that the structure of the hrp gene cluster in X. oryzae pv. oryzae is unique.  相似文献   

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