首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 62 毫秒
1.

The effects of the texture of seed coats of three pulse cultivars, of which two, TVu12349 (wrinkled cowpea) and Borno brown (rough cowpea) belonged to Vigna unguiculata, and one, Bunmonu (smooth bambara groundnut) belonged to Vigna subterranea, as well as pre-and post-oviposition application on the efficacy of the essential oils of clove (Syzgium aromaticum), West African black pepper (WABP) (Piper guineense) and ginger (Zingiber officinale), against oviposition and development of Callosobruchus maculatus, were investigated under prevailing storage conditions (32-35°C and 40-50% RH) and 24 h darkness in Maiduguri, Nigeria. Seed coat texture influenced the bioactivity of the essential oils, especially clove oil, against oviposition and the proportion of C. maculatus adults that emerged significantly more than host species: the mean numbers of eggs laid on the smooth-seeded Bunmonu, the rough-seeded Borno brown and the wrinkled TVu12349 were 16.9, 16.7 and 24.2%, respectively; adult emergence was 31.1% in the wrinkled TVu12349, 45.3% in the rough-seeded Borno brownand 10.2% in the smooth-seeded Bunmonu. The smooth-seeded Bunmonu reduced oviposition in seeds treated with clove oil by 91.4% and 98.4% relative to the mean number of eggs laid in the rough-seeded and the wrinkled Tvu12349, respectively; comparable figures of oviposition reduction by Bunmonu in untreated seeds were 4.8 and 15.9% relative to the mean number of eggs laid in Borno brown and Tvu12349, respectively. Both pre-and post-oviposition application of the essential oils significantly suppressed oviposition and/or adult emergence. In the pre-oviposition application, treatment of bambaranut seeds with clove, WABP and ginger oils at the rate of 1 mg/5 g seed reduced the mean number of eggs laid by C. maculatus by 70.7, 98.7 and 86.2%, respectively, relative to the number of eggs laid in untreated seeds. Post-oviposition treatments were, however, more effective on average, than pre-oviposition treatments in reducing the proportion of C. maculatus adults that emerged. In the post-oviposition application, no adult C. maculatus emerged in bambaranut seeds treated with clove oil at the rate of 0.5 or 1 mg/5 g seed.  相似文献   

2.
The cowpea bruchid (Callosobruchus maculatus F.) (Chrysomelidae: Bruchini) is a major pest of stored cowpea grain. With limited available technologies for controlling the bruchid, transgenic cowpeas with bruchid resistance genes engineered into them could become the next management tools. An investigation was made of two different sets of potential transgenic insecticidal compounds using an artificial seed system: (i) CIP-PH-BT-J and recombinant egg white avidin, and (ii) avidin and wheat alpha-amylase inhibitor. CIP-PH-BT-J (0.1%; 1000 mg kg(-1)) and recombinant egg white avidin (0.006%; 60 mg kg(-1)) incorporated separately into artificial seeds caused 98.2 and 99% larval mortality rates respectively. Combining CIP-PH-BT-J and avidin in the same artificial seed provided additional mortality compared with each factor incorporated singly; no insects survived in seeds with the combined toxins. Similarly, when avidin and wheat alpha-amylase inhibitor (alphaAI) (1%; 10 g kg(-1)) were incorporated separately into artificial seeds, this caused 99.8 and 98% mortality respectively. However, in combination, avidin and alphaAI did not increase mortality, but they did cause a significant increase in developmental time of the cowpea bruchids. These results emphasize that the joint action of potential insecticidal compounds cannot be predicted from results obtained separately for each compound, and they suggest potential transgenes for further consideration.  相似文献   

3.

Extracts from nine plant materials were tested in choice and no-choice tests as oviposition deterrents for cowpea bruchid, Callosobruchus maculatus (F.) on chickpea, Cicer arietinum L. Seed treatment with 0.1% crude extract of materials resulted in a significant reduction in ovipositional preference of the bruchid. The highest repellency was found in Rhazya stricta leaves (82%), Azadirachta indica seeds (76.8%), Heliotropium bacciferum aerial parts (59.2%) and citrus peels (58.6%). Progeny production was significantly reduced: only 11.5, 11.9, 12.4, 13.4 and 14.8% of the eggs deposited reached adulthood in R. stricta, neem seeds, Piper nigrum, citrus peels and H. bacciferum, respectively. F1 females laid significantly fewer eggs in response to R. stricta, neem seeds, Eugenia caryophyllata cloves, H. bacciferum, citrus peels and P. nigrum. Percentage reduction in F2 progeny ranged between 71.4% with R. stricta-treated seeds and 24.5% in the P. nigrum treatment.  相似文献   

4.
Hilf ME 《Phytopathology》2011,101(10):1242-1250
Huanglongbing is an economically damaging disease of citrus associated with infection by 'Candidatus Liberibacter asiaticus'. Transmission of the organism via infection of seeds has not been demonstrated but is a concern since some citrus varieties, particularly those used as rootstocks in commercial plantings are propagated from seed. We compared the incidence of detection of 'Ca. Liberibacter asiaticus' DNA in individual fruit peduncles, seed coats, seeds, and in germinated seedlings from 'Sanguenelli' sweet orange and 'Conners' grapefruit fruits sampled from infected trees. Using real-time quantitative PCR (qPCR) we detected pathogen DNA in nucleic acid extracts of 36 and 100% of peduncles from 'Sanguenelli' and from 'Conners' fruits, respectively. We also detected pathogen DNA in extracts of 37 and 98% of seed coats and in 1.6 and 4% of extracts from the corresponding seeds of 'Sanguenelli' and 'Conners', respectively. Small amounts of pathogen DNA were detected in 10% of 'Sanguenelli' seedlings grown in the greenhouse, but in none of 204 extracts from 'Conners' seedlings. Pathogen DNA was detected in 4.9% and in 89% of seed coats peeled from seeds of 'Sanguenelli' and 'Conners' which were germinated on agar, and in 5% of 'Sanguenelli' but in none of 164 'Conners' seedlings which grew from these seeds on agar. No pathogen DNA was detected in 'Ridge Pineapple' tissue at 3 months post-grafting onto 'Sanguenelli' seedlings, even when pathogen DNA had been detected initially in the 'Sanguenelli' seedling. Though the apparent colonization of 'Conners' seeds was more extensive and nearly uniform compared with 'Sanguenelli' seeds, no pathogen DNA was detected in 'Conners' seedlings grown from these seeds. For either variety, no association was established between the presence of pathogen DNA in fruit peduncles and seed coats and in seedlings.  相似文献   

5.
Three insect growth regulators (IGR), the chitin synthesis inhibitors (CSI) teflubenzuron and hexaflumuron and the juvenile hormone mimic (JHM) pyriproxyfen, as well as the organophosphate (OP) pirimiphos-methyl, were evaluated for their activity against the cowpea weevil, Callosobruchus maculatus (F), in cowpea seeds stored for up to 8 months post-treatment. The initial activity data showed that, based on LC50 level, teflubenzuron had strong ovicidal activity (LC50 = 0.056 mg kg(-1)) followed by pirimiphos-methyl (1.82 mg kg(-1)) and pyriproxyfen (91.9 mg kg(-1)). The residual activity data showed that none of the IGRs tested had strong activity when applied at 200 mg kg(-1) in reducing the oviposition rates of C maculatus at various storage intervals up to 8 months post-treatment. However, teflubenzuron reduced adult emergence (F1 progeny), achieving control ranging from 96.2% at 1 month to 94.3% at 8 months. Hexaflumuron showed a similar trend in its residual activity, ranging between 93.8% control at 1 month to 88.2% control at 8 months post-treatment. However, pyriproxyfen was more active than the CSIs tested and caused complete suppression (100% control) of adult emergence at all storage intervals. Unlike the IGRs tested, pirimiphos-methyl applied at 25 mg kg(-1) was more effective in reducing oviposition rates of C maculatus up to 8 months post-treatment. A strong reduction of adult emergence was also observed at various bimonthly intervals (98.6% control at 1 month to 91.6% control at 8 months post-treatment). The persistence of hexaflumuron and pirimiphos-methyl in cowpea seeds was also studied over a period of 8 months. The loss of hexaflumuron residue in treated cowpeas (200 mg kg(-1)) was very slow during the first month post-treatment (4.43%). At the end of 8 months, the residue level had declined significantly to 46.4% of the initial applied rate. The loss of pirimiphos-methyl residue in treated cowpeas (25 mg kg(-1)) was relatively high during the first month post-treatment (36.7%) and increased to 81.6% after 8 months.  相似文献   

6.
Abstract

The efficacy of two application rates of powdered fruits of four types of peppers (Capsicum spp.) was evaluated for the control of Callosobruchus maculatus (F). The various pepper powders at 2.5 g‐5.0 g per 250 g of seed were effective in reducing oviposition and damage to cowpea seeds. The pepper type Capsicum frutescens var. yarmunchi was the most effective in discouraging oviposition and minimizing damage to the seed, as indicated by the significantly lower number of emergence holes. The seed quality and viability were not affected by the powdered pepper fruit treatment. The result is indicative of the potential for the use of powdered fruits of some peppertypes in protecting stored cowpea seeds against C. maculatus.  相似文献   

7.
An experimental protocol consisting in the colonisation of pregerminated bean seeds dressed withTrichoderma sp. was used in order to study the mechanisms correlated with the protective effect againstPythium splendens. Seed dressed with TH-11 (T. koningii) for 24 h presented a higher protective effect and a higher level of seed colonisation as compared to those dressed with TH-13 (T. longibranchiatum). The levels of seed coat colonisation by TH-11 and TH-13 was shown to be correlated with the carboxymethylcellulase activity, as measured in the seed coats retreived from germinating dressed bean seeds. The seed coat colonisation was also associated with an increased activities of endo-1,3--glucanase and endochitinase measured in seed extracts, and an inhibitory effect of seed extracts onPythium sporangia germination. Pretreatment of TH-13-dressed seeds with a commercial cellulase improved all parameters mentioned above, thus suggesting a role of cellulase activity in the colonisation process and the linked protective effect. The possible role of hydrolytic enzymes in the protective effects is discussed.  相似文献   

8.
The insecticidal activity of lauric, oleic and linoleic acids against Callosobruchus maculatus on cowpea was investigated in laboratory bioassays. In pre-oviposition grain treatments, it was found that, at dosages between 1.96 and 11.59 kg-lauric acid had no effect on progeny development, while the oily oleic and linoleic acids were active in reducing progeny development. The active fatty acids had no effect on oviposition (in no-choice experiments) or on mortality of adults or larvae that successfully penetrated treated cowpea seeds, and their insecticidal activity, like that of fixed vegetable oils, depended mainly on ovicidal action. When applied to cowpeas in a pure state, oleic acid had an LC50 value of 1.64mlkg?1, which made it approximately 3 and 8 times more toxic against eggs of C. maculatus than groundnut oil and linoleic acid respectively. When the ovicidal activities of the three fatty acids were tested by dipping egg-infested seeds in acetone- based solutions, they were all found to be similarly toxic, lauric, oleic and linoleic acids having LC50, values of 40, 38 and 26 ml litre?1 respectively (with overlapping 95% C.L.). These values made them 2-4 times more toxic than acetone-based solutions of groundnut and traditional coconut oils. The possibility of employing fatty acids in large-scale and traditional small-scale food storage systems is discussed.  相似文献   

9.
Seedbank density is an important aspect that determines the amount of damage that the parasitic weed, purple witchweed (Striga hermonthica; hereafter, called “Striga”), causes on its crop hosts. The seedbank depletion of Striga was measured in Mali and Niger during the 2004 rainy season under the host crops, pearl millet and sorghum, the non‐host crops, cowpea and sesame, the intercrops of pearl millet or sorghum with cowpea or sesame, and fallow with or without weeding. Two methods were used and compared; namely, a seed bag method and a soil‐sampling method. The fate of the seeds was assessed by a seed press test. Seed germination, as determined by the presence of empty seed coats, contributed most to the seedbank depletion of Striga under a variety of crop covers and fallow. The highest seedbank depletion was found under the monocultures of the host crops. The intercrops of the host and non‐host crops caused less seedbank depletion, followed by the monocultures of the non‐host crops, fallow, and bare soil. The seed bag method and the soil‐sampling method yielded similar percentages of seedbank depletion, while the former allowed for distinguishing between the germinated and diseased seeds. The results suggest that, although all the tested crop species can cause the seed germination and seedbank depletion of Striga, management by using host cereal crops causes the highest amount of germination and has the highest potential to deplete the soil seed bank, provided that seed production is prevented.  相似文献   

10.
BACKGROUND: The present study investigated the effect of seven Bacillus‐species plant‐growth‐promoting rhizobacteria (PGPR) seed treatments on the induction of disease resistance in cowpea against mosaic disease caused by the blackeye cowpea mosaic strain of bean common mosaic virus (BCMV). RESULTS: Initially, although all PGPR strains recorded significant enhancement of seed germination and seedling vigour, GBO3 and T4 strains were very promising. In general, all strains gave reduced BCMV incidence compared with the non‐bacterised control, both under screen‐house and under field conditions. Cowpea seeds treated with Bacillus pumilus (T4) and Bacillus subtilis (GBO3) strains offered protection of 42 and 41% against BCMV under screen‐house conditions. Under field conditions, strain GBO3 offered 34% protection against BCMV. The protection offered by PGPR strains against BCMV was evaluated by indirect enzyme‐linked immunosorbent assay (ELISA), with lowest immunoreactive values recorded in cowpea seeds treated with strains GBO3 and T4 in comparison with the non‐bacterised control. In addition, it was observed that strain combination worked better in inducing resistance than individual strains. Cowpea seeds treated with a combination of strains GBO3 + T4 registered the highest protection against BCMV. CONCLUSION: PGPR strains were effective in protecting cowpea plants against BCMV under both screen‐house and field conditions by inducing resistance against the virus. Thus, it is proposed that PGPR strains, particularly GBO3, could be potential inducers against BCMV and growth enhancers in cowpea. Copyright © 2009 Society of Chemical Industry  相似文献   

11.
In an area of Nigeria where downy mildew of maize is present, histological assessment of maize seed revealed the presence of mycelium and oospores of Peronosclerospora sorghi in the kernels. Seed transmission of downy mildew of maize was demonstrated when grain purchased at local markets gave mean seedling infection rates of 12·3% (untreated seeds) and 10·0% (in metalaxyl-treated seeds) within 7 days of emergence, after storage in a desiccator for 30 days. When untreated seeds taken from nubbin ears of systemically infected plants from four states in southern Nigeria were planted at 9 days (17–22% moisture content) and 27 days (9–22% moisture content) after harvest, 20·0% infected seedlings resulted in both trials. Seeds from Borno state in northern Nigeria had 26·6% systemic seedling infection after 9 months of storage at 11% moisture content. When seeds harvested from maize plants inoculated with P. sorghi through silks were examined histologically, hyphae of P. sorghi were observed mostly in the scutellum of the embryo. Transmission of disease to seedlings was observed when the silk-inoculated seeds (9% moisture content) were planted in pots in a greenhouse; however, no disease transmission was observed when such seeds were planted in the field. The epidemiological significance of seed transmission is discussed with particular reference to survival of inoculum and development of epidemics. Also noteworthy is the overall significance of seed transmission in Nigeria, where the major source of seed is that saved by farmers from their grain crop, occasionally supplemented by seed bought from the local market.  相似文献   

12.
A bioassay procedure for detecting and evaluating pest control agents in plant extracts was developed using the pulse beetle,Callosobruchus chinensis L. Four plant species common in Egypt,Clerodendrum inerme, Nerium oleander, Ipomoea palmata andAtriplex lentiformis, were extracted with petroleum ether. The crude extracts were evaluated as surface protectants for cowpea(Vigna sinensis) seeds againstC. chinensis infestation. All extracts showed some degree of oviposition deterrent effect at one or more of the concentrations applied. The extracts also had conspicuous activity against the eggs ofC. chinensis deposited on treated seeds, leading to a pronounced reduction in F1 progeny. At 0.5%, theI. palmata extract provided 97% seed protection against insect infestation, followed byN. oleander (94%),C. inerme (93%) andA. lentiformis (89%). Moreover, theI. palmata extract showed good insecticidal activity as a result of contact toxicity. TheC. inerme extract was the least toxic material to the insects.  相似文献   

13.
Laboratory and glasshouse experiments demonstrated that priming of carrot seeds infected with Alternaria dauci did not affect the rate of transmission of the pathogen. Iprodione applied as a dust to unprimed, infected seeds at 5 ga.i. per kg seed effectively reduced disease transmission. Iprodione (0.1% a.i.) or thiram (0.1% a.i.) added in polyethylene glycol (PEG; filter paper or bubble-column priming systems) only partially reduced infection. Further dusting of the primed and dried seeds with iprodione, or alternatively application of that fungicide in a polymer film coat as the final stage in the process engineering of carrot seeds, was necessary to achieve complete control. The addition of thiram in the priming fluid, followed by an application of iprodione to the primed and dried seeds, improved the emergence and yield of carrots in the field.  相似文献   

14.
BACKGROUND: Infestation of seeds by pests during storage leads to deterioration in quality. Seed coating is an effective option to overcome the menace. Unlike synthetic fungicidal seed coats, little is known of those based on botanicals. This study aims at developing azadirachtin‐A‐based pesticidal seed coats to maintain seed quality during storage. RESULTS: Polymer‐ and clay‐based coats containing azadirachtin‐A were prepared and evaluated for quality maintenance of soybean seed during storage. Gum acacia, gum tragacanth, rosin, ethyl cellulose, hydroxyethyl cellulose, polyethyl methacrylate, methyl cellulose, polyethylene glycol, polyvinyl chloride, polyvinyl acetate, polyvinyl pyrrolidone and Agrimer VA 6 polymers and the clay bentonite were used as carriers. The time for 50% release (t1/2) of azadirachtin‐A into water from the seeds coated with the different coats ranged from 8.02 to 21.36 h. The half‐life (T1/2) of azadirachtin‐A in the coats on seed ranged from 4.37 to 11.22 months, as compared with 3.45 months in azadirachtin‐A WP, showing an increase by a factor of nearly 1.3–3.3 over the latter. The coats apparently acted as a barrier to moisture to reduce azadirachtin‐A degradation and prevented proliferation of storage fungi. Polyethyl methacrylate, polyvinyl acetate and polyvinyl pyrrolidone were significantly superior to the other polymers. Azadirachtin‐A showed a significant positive correlation with seed germination and vigour, and negative correlation with moisture content. CONCLUSION: Effective polymeric carriers for seed coats based on azadirachtin‐A are reported. These checked seed deterioration during storage by acting as a barrier to moisture and reduced the degradation of azadirachtin‐A. Copyright © 2008 Society of Chemical Industry  相似文献   

15.
Acidovorax valerianellae , the causal agent of bacterial black spot of corn salad and responsible for severe economic losses to this vegetable in France, was successfully transmitted to corn-salad plants by artificially inoculated seeds in glasshouse and field experiments. In the field experiments, climatic data recorded under plastic tunnels indicated that increasing temperature and relative humidity increased symptom development. To investigate the possible contamination of commercial seedlots of corn salad, a seed test was developed consisting of soaking batches of seeds (five batches each of 5000, 1000, 500 and 100 seeds) overnight at 4°C in distilled sterile water, followed by dilution-plating of seed extracts on TSAV (tryptic soya agar for A. valerianellae ) semiselective medium. Suspected colonies were identified by biochemical and pathogenicity tests or, within 24 h, using antibodies specific to A. valerianellae . Acidovorax valerianellae was detected in three lots. Seed infection levels ranged from 0·10 to 0·89% of contaminated seeds and a single seed carried up to 1800 A. valerianellae colony-forming units.  相似文献   

16.
进口大豆上菜豆荚斑驳病毒的免疫捕获巢式RT-PCR检测   总被引：4，自引：0，他引：4  
于翠  杨翠云  宋绍祎  洪健 《植物检疫》2006,20(4):201-204
利用DAS-ELISA对进口大豆上BPMV进行检测发现,从美国进口的部分大豆样品对BPMV的多抗血清呈阳性反应;利用免疫吸附电镜观察发现,ELISA检测阳性的大豆种皮病汁液中存在直径约30nm的球状病毒粒子.根据BPMV外壳蛋白（CP）基因的保守序列设计了2对嵌合引物,建立了BPMV的高灵敏的免疫捕获巢式RT-PCR（IC-nested RT-PCR）检测方法.该方法经免疫捕获、反转录和2轮PCR扩增,能从带毒大豆种子中扩增到预期大小的DNA条带.序列测定与分析表明此条带的序列为BPMV部分CP基因,在系统关系树上与BPMV的其它分离物形成一簇亲缘关系很近.实验表明从进境大豆上检测到了BPMV.  相似文献   

17.
Field control failures with pirimiphos-methyl against the rice moth, Corcyra cephalonica (Stainton), in Weslaco, Texas, USA, led us to investigate the susceptibility of this particular strain to pirimiphos-methyl, spinosad, pyrethrins synergized with piperonyl butoxide, and pirimiphos-methyl combined with synergized pyrethrins. In laboratory bioassays, 50 eggs of C cephalonica were exposed to untreated and insecticide-treated corn and sunflower seeds to determine larval survival after 21 days, egg-to-adult emergence after 49 days, and larval damage to seeds at both exposure periods. Pirimiphos-methyl at both 4 and 8 mg kg(-1) did not prevent larval survival or egg-to-adult emergence of C cephalonica on either corn or sunflower seeds, and seed damage was evident at both rates. The C cephalonica strain was highly susceptible to spinosad at 0.5 and 1 mg kg(-1). At both spinosad rates, reduction in larval survival, egg-to-adult emergence, and seed damage relative to the control treatment was > or = 93% on both corn and sunflower seeds. Pirimiphos-methyl and spinosad were generally more effective against C cephalonica on corn than sunflower seeds. The C cephalonica strain was completely controlled on corn treated with 1.5 mg kg(-1) of pyrethrins synergized with 15 mg kg(-1) of piperonyl butoxide. Many larvae survived and became adults on corn treated with synergized pyrethrins at < or = 0.75 mg kg(-1). Corn treated with pirimiphos-methyl at 4, 6 or 8 mg kg(-1) in combination with 0.38 to 1.5 mg kg(-1) of synergized pyrethrins reduced larval survival by > or = 95%, egg-to-adult emergence by > or = 97%, and seed damage by > or = 94%. Our results suggest that the C cephalonica strain can be controlled on corn by combining pirimiphos-methyl with synergized pyrethrins or with synergized pyrethrins at the labeled rate. Although spinosad is not currently labeled for use on stored corn and sunflower seeds, it appears to be effective against C cephalonica on both commodities at very low rates.  相似文献   

18.
Yarrow (Achillea millefolium L.) has arisen as a problem weed in arable land in New Zealand. A spring-sown yarrow population of 58 plants m?2 produced approximately 243000 seeds. These were capable of immediate germination in the autumn, but virtually no germination occurred in the winter and up to 80–100% at other times of the year. Seeds are positively photoblastic, but a considerable percentage of seed (>30%) may germinate in the dark after chilling, coat pricking, exposure to high nitrate concentrations or to alternating temperatures. Seed buried at 32 cm in undisturbed soil lost viability slowly over 4 years while seed in the top 8 cm lost viability almost completely within 2 years.  相似文献   

19.
江苏省江都市稻田黑褐色谷壳杂草稻种子主要集中在表层土壤,即0～2 cm的土层内,占黑褐色谷壳杂草稻种子数量的92.65%。在土壤种子库中,黑褐色谷壳杂草稻数量在严重危害田块是黄色谷壳稻的17.9倍,中等危害田块为1.58倍,轻度危害田块仅0.17倍。  相似文献   

20.
小麦黑胚病种子带菌的光镜和扫描电镜观察   总被引：6，自引：0，他引：6  
 检测表明京双16、聊89-1、聊89-2、聊91-1、聊91B18-27-1及鲁麦12 6个小麦品种(品系)的黑胚病病粒率为7.6%~45.7%,病情指数为3.2%~13.5%,以聊89-1最轻,鲁麦12最重。借助光学显微镜和扫描电子显微镜对6个品种(品系)的黑胚种子和健康胚种子进行了比较观察,证实了黑胚种子胚中链格孢菌(Alternaria)的存在,此外,亦观察到了黑胚种子寄藏有类似于长蠕孢属(Helminthosporium)、枝孢属(Cladosporium)等真菌的菌体。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号