The efficacy of spinosad against the western flower thrips, Frankliniella occidentalis, and its impact on associated biological control agents on greenhouse cucumbers in southern Ontario   总被引：1，自引：0，他引：1  

Jones T  Scott-Dupree C  Harris R  Shipp L  Harris B 《Pest management science》2005,61(2):179-185

Insecticides are the most commonly used tactic to control western flower thrips (WFT), Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), on greenhouse cucumber. However, WFT has developed resistance to several of the insecticides presently in use. In addition, some of these insecticides adversely affect greenhouse biological control agents used to control WFT, resulting in subsequent pest resurgence. Therefore, there is a need to identify novel insecticides with unique modes of action for use in integrated pest management (IPM) programs to effectively control WFT with minimal impact on associated biological control agents. In laboratory bioassays conducted in 2001, immature and adult WFT and three associated greenhouse biological control agents: Amblyseius cucumeris Oudemans (Acarina: Phytoseiidae), Orius insidiosus Say (Hemiptera: Anthocoridae) and Encarsia formosa Gahan (Hymenoptera: Aphelinidae) were exposed to direct, direct/residual, and residual contact applications of the novel biopesticide, spinosad (Conserve 120 SC), and the industry standard for whitefly control, endosulfan (Thiodan 50 WP). In all three types of assay, spinosad was effective against immature and adult WFT life stages. It showed low toxicity to A. cucumeris, moderate toxicity to O. insidiosus and high toxicity to E formosa. Greenhouse studies involving exposure of immature and adult WFT and adult biological control agents to cucumber leaves sprayed previously with spinosad supported the laboratory data. Spinosad showed low toxicity to A. cucumeris exposed to leaves 1 day after treatment (DAT), moderate toxicity to O. insidiosus 1 and 8 DAT, and high toxicity to E. formosa up to 28 DAT. These data, along with spinosad's unique mode of action, suggest it would be a valuable reduced-risk control agent for greenhouse cucumber IPM programs.  相似文献   

A radiochemical and gas-chromatographic study of the determination of dichlorvos residues in stored grain     

Richard A. Hoodless  Frank J. Jackson  Kenneth R. Tarrant  Brenda E. Griffiths 《Pest management science》1974,5(5):555-559

An investigation into the extraction of dichlorvos from stored grain and satisfactory storage conditions for samples received for analysis has been carried out using [³²P]-dichlorvos. It has been shown that samples can be effectively stored at —17° C and that methanol can be used for the extractable dichlorvos but does not remove the organophosphorus residue bound to the grain.  相似文献   

Postlarvae and juveniles of a selected line of Penaeus stylirostris are resistant to infectious hypodermal and hematopoietic necrosis virus infection     

Kathy F. J. Tang  Stephanie V. Durand  Brenda L. White  Rita M. Redman  Carlos R. Pantoja  Donald V. Lightner 《Aquaculture (Amsterdam, Netherlands)》2000,190(3-4):203-210

A susceptibility study of postlarvae (PL) and juvenile Super Shrimp®, a selected line of Penaeus stylirostris, was conducted to compare their resistance to infectious hypodermal and hematopoietic necrosis virus (IHHNV) infection to that of a specific pathogen free (SPF) population of P. vannamei. Super Shrimp® PLs were fed with IHHNV-infected shrimp tissue for 2 days and then maintained on a pelletized ration for an additional 28 days. PLs were sampled at days 0, 1, 2, 3, 4, 6, 10, 15, 20, 25 and 30. There was no apparent mortality during the experimental period. Tissue DNA extracted from the PLs was analyzed for the presence of IHHNV by PCR. Low levels of IHHNV were detected only in DNA extracts from samples at days 1, 2, and 3. No IHHNV DNA was detected from days 4 to 30. The days that the PLs were weakly IHHNV-PCR positive were during the period that they were being fed with IHHNV-tissue, and thus, the IHHNV DNA signal was suspected to be from the infected tissue used as a feed. Through both histology and in situ hybridization, we confirmed that tissues of Super Shrimp® PLs were not infected with IHHNV. PCR results of another IHHNV challenge study with juveniles of Super Shrimp® were similar to those with PLs. These results indicate that IHHNV did not replicate in the PL and juvenile Super Shrimp®. In contrast, P. vannamei juveniles, which were used as a positive control, showed a more intense IHHNV infection, as determined by PCR detection, beginning at 6 days postchallenge and increasing throughout the remainder of the study. In addition, the IHHNV-infected P. vannamei at 30 days postchallenge showed histological changes characteristic of IHHNV infection and had a positive reaction for IHHNV with in situ hybridization. Our studies show that Super Shrimp® are resistant to IHHNV infection. This is the first unequivocal demonstration of resistance to viral infection in shrimp.  相似文献   

Degradation of an Atrazine and Metolachlor Herbicide Mixture in Pesticide-Contaminated Soils from Two Agrochemical Dealerships in Iowa     

Arthur  Ellen L.  Perkovich  Brenda S.  Anderson  Todd A.  Coats  Joel R. 《Water, air, and soil pollution》2000,119(1-4):75-90

The fate of atrazine and metolachlor,applied as a mixture, in soil taken from twopesticide-contaminated sites in Iowa (denoted as Alphaor Bravo) were determined in laboratory studies. Atrazine and metolachlor degradation, as well asatrazine mineralization, were greater in soilcollected from Kochia scoparia L. (Schrader)rhizosphere than in soils from unvegetated areas. Theradiolabeled ¹⁴C-carbinol and¹⁴C-morpholinone metabolites were identified in¹⁴C-metolachlor-applied soil 60 d aftertreatment. The half-life for atrazine in Alpha soilwas significantly less in the rhizosphere soil (50 d)than in unvegetated soil (193 d). Quantities ofspecific atrazine degraders were one to two orders ofmagnitude greater in Bravo soils than in Alpha soils. In an experiment with plants present, significantlymore ¹⁴C-atrazine was taken up by K.scoparia (9.9% of the applied ¹⁴C) than by Brassica napus L. Significantly less atrazine wasextractable from soils vegetated with K.scoparia than from soils vegetated with B.napus or unvegetated soils.  相似文献   

Mutations in RNAi rescue aberrant chemotaxis of ADAR mutants     

Tonkin LA  Bass BL 《Science (New York, N.Y.)》2003,302(5651):1725

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Soil random roughness and depression storage on coffee farms of varying shade levels     

Brenda B. Lin  Paul L. Richards 《Agricultural Water Management》2007,92(3):194-204

Water availability in rainfed coffee agroecosystems is an important factor in determining the production success of the crop. In this study, an estimate of soil water capture and storage was conducted in order to understand the differences of soil water availability among coffee farms or various management intensities, distinguished here by differences in shade cover level. Measurements of effective soil depression storage, leaf litter and soil moisture were taken in each of the sites. These measurements were taken to better understand how different shade coffee systems may gain or lose opportunities to keep water within the system due to contributions of shade. Three sites of varying shade were chosen in the Soconusco region of Chiapas, Mexico. The medium (30-50% cover) shade site was found to be more effective for precipitation capture when compared to the low (10-30% cover) shade site because of a larger value of effective depression storage (t-test, p = 0.05) due to increased soil roughness. This conclusion was supported by significantly higher soil moisture measurements in the medium shade site when compared to the low shade site in the dry season (repeated measure GLM, p = 0.001). The high shade (60-80% cover) site was found to have a greater slope than the other two sites, yielding smaller effective storage capacities; yet the high shade site was able to retain 15% of the available rainfall during the dry season through surface storage, possibly because of greater leaf litter and other shade contributions. Farmers may consider the use of shade trees within coffee farms as a practical method toward preserving water within the agroecosystem.  相似文献   

Microbial Indicators of Faecal Contamination in Water: A Current Perspective   总被引：2，自引：0，他引：2  

Pam Tallon  Brenda Magajna  Cassandra Lofranco  Kam Tin Leung 《Water, air, and soil pollution》2005,166(1-4):139-166

It is well documented that faecal contamination of drinking water has caused numerous disease outbreaks. Because the risks of disease outbreaks correlate with the incidence of faecal contamination, faecal bacteria are used as indicators of faecal contamination and hence, the possible presence of disease-causing organisms. However, different microbiological faecal indicators are used in different countries and jurisdictions. Therefore, it is important to understand the potentials and limitations of these indicator organisms before realistically implementing guidelines and regulations to safeguard our water resources. This review considers the history of indicator organisms, the evolution of the analytical methodologies (biochemical and molecular) and addresses the advantages and limitations of current faecal indicator microorganisms.  相似文献   

Reproductive Biology in Wild and Silvicultural Managed Populations of Escontria chiotilla (Cactaceae) in the Tehuacán Valley, Central Mexico     

Brenda Oaxaca-Villa  Alejandro Casas  Alfonso Valiente-Banuet 《Genetic Resources and Crop Evolution》2006,53(2):277-287

Reproductive biology of the columnar cactus Escontria chiotilla was analysed in wild and silvicultural managed populations in the Tehuacán Valley, Central Mexico, where this cactus is under domestication because of its edible fruits. Anthesis is diurnal, flowers opening between 8:00 and 17:00 h, the period between 12:00 and 13:00 appearing to be crucial in pollination success since at this time the maximum opening of flowers, turgidity of stigma, and activity of flower visitors, as well as the highest nectar production and pollen release occur. The bees Apis mellifera, Bombus pensylvanicus and Xylocopa mexicanorum, and the hummingbirds Amazilia violiceps, Cynanthus sordidus and Cynanthus latirostris were the most frequent flower visitors during the crucial period, and were observed contacting both stamens and stigma of E. chiotilla. No differences were found in anthesis nor in flower visitors among both population types. Distances separating the populations studied and bridges of individuals of E. chiotilla between them are within the radius that bees and hummingbirds may travel, indicating that spatial barrier to pollen flow are unlikely. Breeding system is self-incompatible. Production of flowers occurs during the whole year in both population types, allowing continual pollen flow among them. This observation confirms reports of high gene flow among the populations studied in previous population genetics studies. The high pollen flow among wild and managed population explains that however the occurrence of artificial selection, the process of domestication is in incipient stages presumably because gene flow counteracts effects of artificial selection.  相似文献   

Introduction to special issue: Meeting the challenges of HIV/AIDS in Southeast and East Asia     

Nicola Piper  Brenda S.A. Yeoh 《Asia Pacific viewpoint》2005,46(1):1-5

Out of a total of 38 million people living with HIV/AIDS globally today, the Asia‐Pacific is home to about 7.4 million – a figure which constitutes a sharp rise to previous years. In absolute numbers, infections in Asia are projected to exceed African figures within a decade. This has largely to do with economic changes towards market‐based capitalism, widening socioeconomic disparities and increased levels of mobility (internal and cross‐border), as for instance in China and Indonesia. Overall, the epidemic in Asia has been described as more complex than in Africa involving a multiplicity of transmission modes. The case studies presented in the contributions to this special issue discuss the connections between issues of mobility, gender, (trans)nationalism and sexuality in understanding the HIV/AIDS challenge in the region. The various ways in meeting the challenges of HIV/AIDS in Southeast and East Asia are analysed, whereby non‐governmental and community‐based responses often emerge as more effective than state interventions.  相似文献   

The use of repellents to reduce predation of tree seed by wood mice (<Emphasis Type="Italic">Apodemus sylvaticus</Emphasis> L.) and grey squirrels (<Emphasis Type="Italic">Sciurus carolinensis</Emphasis> Gmelin)     

Ian H. Willoughby  Richard L. Jinks  Geoff W. Morgan  Harry Pepper  John Budd  Brenda Mayle 《European Journal of Forest Research》2011,130(4):601-611

The loss of tree seed through predation by granivores can be a major cause of regeneration failure in direct seeding systems. Five repellents that were of low toxicity or derived from foodstuffs were investigated for their ability to deter feeding by wood mice (Apodemus sylvaticus L.) and grey squirrels (Sciurus carolinensis Gmelin). In experiments in controlled conditions, when given the option of feeding on unlimited amounts of untreated wheat (Triticum aestivum L.), or wheat treated with aluminium ammonium sulphate, sulphonated fish oil, denatonium benzoate, ziram or capsaicin, all the repellents tested initially deterred feeding, although in one experiment mice showed some habituation to the repellents after 4 weeks. Capsaicin was the most effective treatment, and aluminium ammonium sulphate the least effective, possibly because it did not stick to the wheat grains. When ash (Fraxinus excelsior L.) seed were treated with combinations of aluminium ammonium sulphate, sulphonated fish oil or denatonium benzoate, compared to the freely available untreated seed, mice were deterred by any treatment containing aluminium ammonium sulphate, with effectiveness again declining after 4 weeks. When a mixture of broadleaved tree species were sown on farmland, coating seed with aluminium ammonium sulphate or sulphonated fish oil had no effect on seedling emergence. Capsaicin derived from chilli peppers (Capsicum sp.) showed the greatest potential as a repellent in our work, but no repellent product containing this active ingredient is currently approved for plant protection uses in the United Kingdom. Given its relatively low cost, the use of aluminium ammonium sulphate, a non-toxic repellent based on an approved food additive, which is available formulated as a registered plant protection product in the United Kingdom, may be worth considering for direct sowings where predation pressure from mice is predicted to be particularly high, or where tree species with very palatable seed are being used, to complement other predation mitigation strategies.  相似文献