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1.
Development duration and reproduction rate of the twospotted spider miteTetranychus urticae Koch (Acarina: Tetranychidae) were studied on five different apple cultivars (‘Amasya’ (local cultivar), ‘Golden Delicious’, ‘Granny Smith’, ‘Starking Delicious’ and ‘Starkrimson Delicious’) at 25°C, 65±10% r.h. and 16:8 L:D. In addition, the same parameters were determined on Golden Delicious leaves at three constant temperatures (20°, 30° and 35°C, 65±10% r.h. and 16:8 L:D) in the laboratory.T. urticae performed better on Granny Smith than on the other cultivars, due mainly to high daily egg production (4.6 eggs/♀/day) and the intrinsic rate of natural increase (r m , which was 0.243 ♀/♀/day). The lowestr m was observed on Amasya variety (0.231 ♀/♀/day). Development periods of immature stages ofT. urticae varied from 6.5 to 15.5 days at 35° and 20°C, respectively, for females, and from 5.9 to 14.5 days at 35° and 20°C, respectively, for males. The development thresholds of the eggs and pre-adult stages, respectively, were 10.78° and 8.43°C, and total effective temperatures were 57.80 and 172.41 degree-days. Mean generation time (T o ) of the population ranged from 9.94 days at 35°C to 25.99 days at 20°C. The net reproduction rate increased from 66.99 ♀/♀ at 20°C to 92.19 ♀/♀ at 25°C, and decreased to 84.34 ♀/♀ at 30°C and to 12.04 ♀/♀ at 35°C. The highest r m occurred at 30°C (0.302 ♀/♀/day) and the lowest at 20°C (0.161 ♀/♀/day). http://www.phytoparasitica.org posting Dec. 19, 2003.  相似文献   

2.
The development time and parasitization rate ofDiaeretiella rapae (M’Intosh) onBrevicoryne brassicae (L.) feeding on differentBrassica cultivars was studied in the laboratory at 20°C. The shortest development time from egg to adult parasitoid was 11.6 days on cabbage cv. ‘Yalova 1’ and the longest was 12.1 days on turnip cv. ‘Antep’ and rapeseed cv. local variety. Females lived significantly longer than males on the host plants used in the study. Females and males had the shortest longevity on rapeseed at 11.1 and 5.1 days, respectively. The highest percent parasitism ofB. brassicae byD. rapae was found on cabbage (40.20%), and the lowest was recorded on turnip (32.64%). Our results demonstrate that parasitism rate could be influenced by the plant quality, probably due to the nutritional status of the aphids or to toxic compounds ingested through the plant. Cabbage, cauliflower and broccoli were found to be suitable plants for the parasitoid, considering the development time of pre-adults, and the parasitization rate ofD. rapae onB. brassicae. http://www.phytoparasitica.org posting Jan. 23, 2007.  相似文献   

3.
The effect of rapid and gradual exposure of entomopathogenic nematodes to osmotic stresses on the induction of a dormant state was determined with the nematodeSteinernema feltiae IS-6 infective juveniles (IJs). Rapid exposure of nematodes to glycerol at concentrations of 24% and 28% (w/w) caused the nematodes to enter a dormant state which was characterized by shrinking and impeded motility of all nematodes within 8 h. However, pre-exposure to gradually increasing glycerol concentrations of 5%, 10% and 18% at 4-h intervals resulted in dormancy after 4 h exposure to 24% glycerol. The total time of exposure to glycerol solution was 16 h in gradual osmotic stress. For nematodes exposed to 24% glycerol solution either rapidly or gradually, recovery occurred after 40 min in distilled water. Infectivity of osmotically stressedS. feltiae IJs was evaluated by two criteria, insect mortality and invasion rate. The assays indicated that infectivity of nematodes desiccated by rapid and gradual osmotic stresses was similar to that of fresh nematodes. Rapid exposure ofS. carpocapsae ‘All’,S. riobravis ‘Texas’,S. glaseri ‘NI’ andHeterorhabditis bacteriophora HP88 IJs to the 24% glycerol solution resulted in dormancy within 8 h. These treatments caused mortality of 48.4% and 11.7% amongS. glaseri Nl andH. bacteriophora HP88 IJs, respectively. Similar effects were observed when these nematode species were exposed to increasing osmotic stress of 5%, 10% and 18% at 6-h intervals. Under these same conditions, mortality ofH. bacteriophora HP88 andS. glaseri Nl IJs was 27.5% and 61.8%, respectively. http://www.phytoparasitica.org posting Sept. 29, 2004.  相似文献   

4.
Thirty-four isolates ofFusarium oxysporum f.sp.melonis (F.o.m.) obtained from 205 fields in melon-producing areas in the southeastern Anatolia Region of Turkey were identified on the basis of colony morphology and pathogenicity by the root dip method. In this region the mean prevalence of wilt disease was 88.1% and the mean incidence of disease was 47.5%. Physiologic races 0, 1, 2, and 1,2 of the pathogen were determined by their reactions on differential melon cultivars ‘Charentais T,’ ‘Isoblon’, ‘Isovac’ and ‘Margot’ in the greenhouse. Race 1,2, representating 58.8% (20/34) of all isolates, was widely distributed. Of the other pathogenic isolates, eight were identified as race 0, five as race 1, and one as race 2. This is the first report of physiologic races ofF.o.m. in Turkey. Of 44 melon cultivars tested in the greenhouse for resistance toF.o.m. races, 36 were found to be moderately resistant to race 0, 17 were susceptible to race 1,2, 34.1% were highly resistant to race 1, and 52.2% had moderate resistance to race 2. http://www.phytoparasitica.org posting July 16, 2002.  相似文献   

5.
Pratylenchus thornei densities were monitored in field plots of two winter wheat cultivars in a dry farming area of southern Spain. Samples were taken fortnightly during the wheat-growing season and from the following dry fallow. Under bread wheat cv. ‘Yecora’, densities ofP. thornei increased for 5 to 6 months and then were maintained or slightly decreased thereafter, surviving the summer dry fallow in an anhydrobiotic state (78.2% and 85.3% survival in soil and roots, respectively). Under durum wheat cv. ‘Donpedro’, nematode densities decreased over the growing season, although densities within the roots increased during the first 2 months of the wheat-growing period, indicating that nematodes could penetrate the roots of this cultivar but were unable to reproduce. These observations suggest resistance of wheat cv. Donpedro toP. thornei.  相似文献   

6.
Six heterocyclic alkylating agents were synthesized and examined for activity against the oat stripe pathogenPyrenophora avenae on agar plates and against the barley powdery mildew fungusBlumeria graminis f.sp.hordei on barley seedlings. Radial growth ofP. avenae was not significantly affected by any of the compounds, but four of them,α,α-bis[4,7-bis(2-chloroethyl)-1,4,7-triazacyclononane]-para-xylene[3], 1,4,8,11-tetra(2-chloroethyl)-1,4,8,11-tetraazacyclotetradecane[4], 8,11-bis(2-chloroethyl)-1,4,8,11-tetraaza-5,7-oxocyclotetradecane[5] and 7,16-bis(2-chloroethyl-1,4,10,13-tetraoxa-7,16-diazaoctadecane[6], gave significant reductions in biomass ofP. avenae grown in liquid culture and in powdery mildew infection on barley when used at 25μM. Polyamine biosynthesis was examined by following the incorporation of labeled ornithine into polyamines inP. avenae. The four compounds3–6 which reduced mildew infection all reduced the flux of label through to the polyamines inP. avenae. Whether the reductions in mildew infection caused by these compounds is related to reduced formation of polyamines is not known and awaits investigation. http://www.phytoparasitica.org posting May 22, 2005.  相似文献   

7.
The potential of entomopathogenic nematodes for biological control of the European corn borer (ECB),Ostrinia nubilalis (Hübner), was evaluated under laboratory, screenhouse and field conditions. The ‘All’ and ‘Mexican’ strains ofSteinernema carpocapsae (Weiser) and the ‘HP88’ strain ofHeterorhabditis bacteriophora Poinar were compared in both dose response assays (5, 50 and 500 infective juveniles [IJ] per petri dish containing five 5th-instar ECB eggs; 72 h of incubation) and exposure time assays (3, 6 and 9 h of incubation). In the dose response assays the highest rates of ECB killing resulted from infestation with the Mexican strain ofS. carpocapsae. In the exposure time assays there were no significant differences between the killing rates of the three nematode strains. Sweet corn plants(Zea mays var.saccharata) grown in a screenhouse, were infested with ECB neonates and 4 days later sprayed with a suspension of the Mexican strain ofS. carpocapsae (50,000 IJ per plant). The number of ECB larvae found on treated corn plants after one week was significantly (P=0.05) lower (3- to 5-fold) than the number found on untreated plants. Similar treatment in the field significantly reduced the rate of economic ear damage from 20% to 5%. Contribution from the Agricultural Research Organization. No. 2260-E, 1997 series  相似文献   

8.
The development time, mortality, survivorship and reproduction of the cabbage aphidBrevicoryne brassicae (L.) were evaluated on detached leaves of sixBrassica species (cabbage cv. ‘Yalova 1’, cauliflower cv. ‘Early Snowball’, broccoli cv. ‘Marathon’, turnip cv. ‘Antep’, rapeseed cv. local variety, and wild mustard) at a constant temperature of 20°C. Total development time ofB. brassicae was the shortest (8.9 days) on cauliflower and the longest (10.4 days) on cabbage. Mortality of immature stages varied from 16% on cabbage to 88% on turnip. Longevity of the cabbage aphid was the shortest (6.2 days) on mustard, and the longest (21.8 days) on cauliflower. The net reproductive rate was highest (35.98) on cauliflower, and lowest (1.89) on turnip. The intrinsic rate of increase was 0.2345 on cauliflower, followed by 0.2009 on cabbage, 0.1976 on broccoli, 0.1662 on mustard, 0.1357 on rapeseed, and 0.0465 on turnip. Cabbage, cauliflower and broccoli were susceptible host plants for the cabbage aphid. Rapeseed, turnip and mustard showed resistance to the pest.  相似文献   

9.
The spider mites Tetranychus urticae Koch and Panonychus ulmi (Koch) (Tetranychidae) cause severe economic losses to vegetable farms and deciduous fruit orchards in Turkey. One of their predators, the ladybird beetle Stethorus gilvifrons (Muls.) (Col., Coccinellidae), aggregates on mite-infested patches of plants. The present study assessed whether there is a role for herbivore-induced plant volatiles (HIPVs) and/or odors emitted directly from these two mite species in the aggregative response of ladybird beetles. The olfactory responses of the predator females to volatiles from T. urticae- and/or P. ulmi-infested sweet pepper (four cultivars, viz. ‘Demre’, ‘Yalova Carliston’, ‘Kandil Dolma’ and ‘Yag Biberi’), kidney bean (cv. ‘Barbunya’) and apple (M9 rootstock) were investigated using a two-choice olfactometer. Our results showed that HIPVs emitted from both T. urticae- and P. ulmi-infested plants significantly attracted S. gilvifrons adults for all plants except the sweet pepper cv. Yag Biberi. In addition, it was found that volatiles from apple plants infested by T. urticae and, especially, P. ulmi are more attractive for S. gilvifrons females than those emitted by other infested plants. The results also suggest that the odors of T. urticae adults and their products might influence the attraction of S. gilvifrons females.  相似文献   

10.
In a study of date fruit damage caused byOligonychus spp., we investigated whether the cultivar affects phenology, and on what hosts the mites over-winter. Samples were taken from ‘Deglet Noor’, ‘Barhi’ and ‘Medjool’ trees from mid-April through mid-September during the years 1999–2002. In the ground-cover mites were monitored by collecting Bermuda grass (Cynodon dactylon) under each sampling tree. Over 99% of the mites collected on Deglet Noor and Barhi fruit were identified asO. afrasiaticus. Mean population levels ofO. afrasiaticus reached ten mites or more (initiation of infestation) on Medjool in the second half of May, whereas on Deglet Noor this did not occur before the first week of July. On Barhi the initiation of infestation varied between plots and years, ranging from the second half of May to the beginning of July, but always occurred earlier than Deglet Noor. Mite populations on the pinnae remained low from June through October, not exceeding seven mites per pinna, whereas on fruit strands they reached peak populations of approximately 4000 mites per strand. The sex ratio (proportion of females) ofO. afrasiaticus on fruit of all three cultivars was highly female-biased, usually above 0.85. During winter,O. afrasiaticus was found on Bermuda grass in the orchard ground-cover as well as on fronds of all three cultivars. http://www.phytoparasitica.org posting Jan. 30, 2003.  相似文献   

11.
Eleven soybean cultivars with different levels of susceptibility to virulent isolate SG915 ofCalonectria ilicicola were examined for reaction to metabolites produced by the isolate. When the culture filtrate from isolate SG915 was applied to trifoliates from 11 cultivars, cvs. ‘Cajun’ and ‘Asgrow 7986’ exhibited reduced wilting severity. However, there was no correlation between sensitivity to culture filtrate and susceptibility to the fungal isolate. Wilting severity on cv. ‘Riverside 699’ was greatest when trifoliates were treated with culture filtrates from isolates SG915 (highly virulent) and C31 (less virulent). The dilution end-point for culture filtrates of virulent isolate SG915 was determined to be 1:8. Nonautoclaved culture filtrates caused complete wilt of soybean trifoliates after 36 h, but autoclaved culture filtrates demonstrated a reduced ability to wilt leaves. Electrolyte leakage from treated leaf tissues increased over time regardless of the concentrations of culture filtrate tested. The greatest electrolyte losses were observed during the initial 30 min incubation of leaf tissues. The highest concentration of culture filtrate (50%, v/v) induced more electrolyte loss than the low concentration (10%, v/v) or control. These results suggest that toxic metabolites ofC. ilicicola may be involved in disease development with leaf symptom expression.  相似文献   

12.
The citrus thrips,Scirtothrips aurantii Faure (Thysanoptera: Thripidae), is a pest of mango in South Africa. The aim of the study was to monitor the different stages ofS. aurantii in mango orchards throughout the year. Populations ofS. aurantii were monitored using different methods,i.e., yellow sticky traps, dispersal/emergence traps, counts on fruit and in flowers. Eggs and emergence holes on the new leaves were recorded. The number of adults increased at the end of flowering (September) and remained at high levels until fruiting (November). Low numbers were present from May to August. Much higher population levels were present during 1995/96 than during the 1996/97 season. There was higher infestation present on the cultivar ‘Sensation’ than on ‘Zill’.S. aurantii was present on the fruit for only a short period (less than 10 weeks) during the season and the population was maintained on flush that was present throughout the year.  相似文献   

13.
Feeding sites induced by the root-knot nematodeMeloidogyne artiellia in turnip (Brassica rapa), cabbage (Brassica oleracea) and barley (Hordeum vulgare) were examined by light and electron transmission microscopy, and compared with those formed byM. javanica andM. hapla. The feeding cells ofM. artiellia in turnip and cabbage showed hypertrophy, hyperplasia and vacuolization, and became multinucleate giant cells. In contrast to the typical simple-shaped giant cells ofM. javanica andM. hapla, those ofM. artiellia had an amoeboid structure containing ‘protuberances’, which are distinct from previously reported ‘projects’ of giant cells induced byM. incognita in other plants. Protuberances expanding between vascular cells were observed in young and developed giant cells. Since no cell-wall fragments were found at the bases of the protuberances, either by light or electron microscopy, it is strongly indicated that these structures were caused by local expansion of the giant cells rather than by fusion with adjacent cells. The giant cells ofM. artiellia in barley had regular shapes of giant cells without protuberances, and resembled those induced byM. javanica orM. hapla in turnip and cabbage. http://www.phytoparasitica.org posting Sept. 17, 2006.  相似文献   

14.
Two distinct races ofDitylenchus dipsaci in Israel were identified: one, which infects and damages onion and garlic, reproduces on pea, but does not infect phalaris grass; and a second, which infects and damages phalaris—and, probably, also ‘Saia’ oats—but fails to infect onion and garlic. A new ‘garlic’ race of the nematode does not appear to have been introduced into Israel together with the ‘Lavinia’ garlic cultivar, as previously speculated, but rather the introduced Lavinia clone is highly susceptible to the existing ‘onion and garlic’ race ofD. dipsaci.  相似文献   

15.
The epidemiology ofMetopolophium dirhodum and its natural enemies on winter wheat was studied from 1975 to 1979 inclusive. AlateM. dirhodum colonize wheat from the middle of May onwards. Immigration occurs until mid-June. Population growth rates ofM. dirhodum can be as high as or occasionally even higher than those ofSitobion avenae. InM. dirhodum alatae are formed in a high proportion throughout the epidemic whereas inS. avenae the % of alatae becomes high at the end. In both species most of these alatae seem to emigrate. Both species have a similar potential to become a pest.Samenvatting De epidemiologie vanMetopolophium dirhodum werd bestudeerd van 1975–1989 en vergeleken met die vanSitobion avenae. Beide soorten migreren naar tarwe in de loop van mei. De relatieve populatie groeisnelheid vanM. dirhodum bleek tijdelijk zeer hoog te zijn (verdubbelingstijd 1,7 dag tegenover 2,0 voorS. avenae). Over de gehele periode van de epidemie is er weinig verschil in dagelijkse relatieve groeisnelheid van de populatie.Bij de ineenstorting, die altijd begint voor het deegrijpstadium van de tarwe, is van belang het ontstaan van gevleugelde bladluizen. Deze verlaten merendeels het gewas. Het belang van de natuurlijke vijanden voor de afname van de populatie is niet altijd duidelijk maar is soms groot en veroorzaakt dan een vroege ineenstorting van de plaag. M. dirhodum heeft even grote mogelijkheden de plaagstatus te bereiken alsS. avenae maar door zijn soms tijdelijk groter vermeerderingsvermogen zal het voorspellen moeilijker zijn.  相似文献   

16.
Consumption of pea (Pisum sativum L.) protein-treated wheat flour by the red flour beetleTribolium castaneum (Herbst.), the rice weevilSitophilus oryzae (L.) and the lesser grain borerRhyzopertha dominica (F.), was significantly reduced compared with wheat flour alone. Consumption was affected when the insects were exposed for 3 days to flour disks containing protein-rich fraction of the ‘Bonneville’ pea variety. Antifeedants present in the pea protein fraction are apparently responsible for the reduced feeding response in these species. http://www.phytoparasitica.org posting May 6, 2004.  相似文献   

17.
Fifteen isolates of rust fungi were collected in the United Kingdom and in the Netherlands from severalAllium species. The samples represented three putative rust species. The morphology of the telia, teliospores and urediniospores was investigated. From urediniospores infection structures were induced on leek, and their morphology was described. Telia and teliospores were not available on every sample. Morphology of the infection structures clearly differentiated between ‘leek’ type and ‘chive’ type isolates. The morphology of infection structures ofPuccinia mixta is very similar to that ofUromyces ambiguus, but clearly distinct fromPuccinia allii sensu Jennings from leek. Quantitative differences in urediniospore characters differentiated between the putative species, but there was overlap between the taxa. We conclude that morphology of infection structures of urediniosporelings is a useful trait for identification of rust isolates fromAllium. This is especially true where more than one rust species may occur on the same host species, as withAllium fistulosum.  相似文献   

18.
Apple proliferation (AP), caused by ‘Candidatus Phytoplasma mali’, is an economically important disease affecting many apple-growing areas in Europe. A new TaqMan real-time PCR assay was established for absolute quantification of ‘Ca. P. mali’ by using a single-copy gene of the host plant as a reference, which is amplified with the pathogen DNA in a single-tube reaction. Normalised estimates of phytoplasma concentration are ultimately expressed as the number of phytoplasma cells per host plant cell. The assay was used to monitor the ‘Ca. P. mali’ titre over the course of two growing seasons in roots and branches of symptomatic and asymptomatic but AP-positive apple trees. All 252 root samples from symptomatic and asymptomatic trees tested positive, with an average number of 59.8 ± 5.68 (standard error) and 55.1 ± 9.83 ‘Ca. P. mali’ per host cell, respectively. From the 378 shoot samples analysed, 81% of the symptomatic and only 20% of the asymptomatic samples were AP-positive with an average number of 9.4 ± 1.04 and 0.7 ± 0.13 ‘Ca. P. mali’ per host cell, respectively. This strengthens evidence that not the pathogen occurrence alone but the presence of a certain quantity of ‘Ca. P. mali’ in the aerial tree sections is involved in symptom expression. In addition, pronounced seasonality of the phytoplasma concentration was found, not only in branches, but also for the first time in roots of symptomatic and asymptomatic apple trees. Highest phytoplasma levels in roots were detected from December to May.  相似文献   

19.
兼抗麦长管蚜和大麦黄矮病毒的小麦种质田间鉴定筛选   总被引：1，自引：1，他引：0  
为鉴定筛选兼抗麦长管蚜和大麦黄矮病毒(Barley yellow dwarf virus, BYDV)的小麦种质,采用自然感蚜/感病系数法,对36个外引和远缘杂交选育的小麦种质材料进行了2年的田间鉴定,并分析了感虫性与感病性的相关关系。结果表明,2年中均兼抗麦长管蚜和BYDV的种质仅有KOKIPPCAS、KOK、Amigo-3和PI137739共4个材料,占总鉴定材料的11.11%;对二者均敏感的有98-10-35q-9、186Tm39、Tam200e12-14a、Tam200(27)7、小偃22、西农1376和小偃6号共7个材料,占19.44%。其它材料仅抗虫或仅抗病,或仅在一年中表现抗病或抗虫,如材料98-10-30和98-10-35a8抗麦长管蚜,但对BYDV敏感;材料Tam200(13)G和PIG23(2)C感蚜,但对BYDV有抑制作用。BYDV发生普遍率(发病株率)和严重度(病情指数)与有蚜株率显著相关,严重度还与感蚜指数显著相关,但感病植株的病级均值与有蚜株率无显著相关性。表明自然界长期的进化和选择使许多抗病虫基因得以保存下来,但较多抗性基因只在抗病或抗虫的某一方面表现有效,需给予更多关注。  相似文献   

20.
Leaf extracts ofVitex negundo L,Synadenium grantii Hook. f. andProsopis juliflora (SW) DC, and cake ofAzadirachta indica A. Juss. were evaluated for their efficacy in reducing the population of the green leafhopper,Nephotettix virescens (Distant), and its transmission of rice tungro virus under field conditions. All four plant species tested reduced the population of the vector significantly in both the nursery and main field. The lowest population of the vector was recorded with application of neem cake at 5 kg/0.032 ha of nursery, followed by foliar spray of neem seed kernel extract at 5% in the main field. Rice tungro disease incidence was also less in this treatment, with maximum grain yield of 3580 kg/ha in ‘Kharif’ (July-Oct.) and 3257 kg/ha in ‘Rabi’ (Nov.-March) seasons, and a cost:benefit ratio of 1:3.9 in both seasons. However, the maximum cost:benefit ratio of 1:5.6 and 1:5.8 in Kharif and Rabi seasons, respectively, was recorded withV. negundo.  相似文献   

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