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Michael R. Metcalf DVM MS Lloyd P. Tate DVM Loouis C. Sellett MS 《Veterinary radiology & ultrasound》1989,30(2):80-87
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Robert L. Metcalf 《Pest management science》1989,26(4):333-358
The past 40 years have seen insect resistance to insecticides develop from a scientific curiosity to an immense practical problem that threatens man's ability to control not only the insect pests of agriculture but also the insect vectors that transmit major human and animal diseases. The spread of genes for cross and multiple resistance among insect pests has rendered most of our present insecticides obsolescent and very few novel insecticides are under development as substitutes. The most feasible strategy to maintain adequate control of insect pests is integrated pest management or I P M, in which insecticide management is a useful component. However, much of our present planning for the future of insect control is carried out in ignorance of past failures. We must learn from the past if we are to retain the use of chemical insecticides as a viable component of IPM. 相似文献
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The process of antagonism of Sclerotium cepivorum in white rot affected onion roots by Trichoderma koningii 总被引:4,自引:0,他引:4
Trichoderma koningii (strain Tr5) grew in the epidermal mucilage of onion roots without entering healthy epidermal tissue. When placed on the epidermis of Sclerotium cepivorum -infected roots, T. koningii colonized epidermal passage cells, with little colonization of other epidermal tissues, then branched and spread throughout the root cortical tissues damaged by enzymes and toxins which diffused ahead of S. cepivorum hyphae, and impeded the path of the infection. When T. koningii colonized infected tissue, many S. cepivorum hyphae became detached at septa, cell walls dissolved and many hyphal apices burst. Contact between hyphae was not necessary for lysis to occur. T. koningii produced two endochitinases ( R f 0·15 and 0·24) and two exo-acting chitinolytic enzymes ( R f 0·46 and 0·62) during degradation of crabshell chitin and S. cepivorum cell walls. The R f 0·24 and 0·46 proteins were detected when T. koningii colonized S. cepivorum -infected roots and are likely to be a component of the antagonism process. 相似文献
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Larry G. Hansen Elizabeth M. Cozzi Robert L. Metcalf Terry K. Hansen 《Pesticide biochemistry and physiology》1985,24(1):136-148
The oxons of leptophos, its desbromo analog, and its ethoxy analog all inhibit hen brain neurotoxic esterase (NTE) to a similar degree in vitro, but have large differences in minimum effective oral doses for organophosphorus-induced delayed neurotoxicity. The potencies of leptophos and ethoxyleptophos are increased 10-fold when administered to hens intravenously (iv), but the potency of desbromoleptophos is nearly the same whether administered iv or po. Leptophos distributes nearly five times more rapidly from the central compartment than does desbromoleptophos, and its attenuated oral potency may be due to slower net absorption and/or dilution by compartments other than nervous tissue. Intravenously administered phenylphosphonothionates are excreted rapidly into the gastrointestinal tract and a large proportion of the dose is eliminated in the first 48 hr. Indirect evidence indicates that ethoxyleptophos is more rapidly degraded and ethoxyleptophos-inhibited NTE recovers more rapidly than does NTE inhibited by leptophos or desbromomleptophos. It is proposed that differential aging of ethoxyleptophos chiral isomers as well as pharmacokinetic factors may contribute to the apparently anomalous behavior of these three analogs. 相似文献
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