Dienoic acid contents of rats with linoleic acid and pyridoxine deficiencies

Low dienoic acid content of the tissues of rats has been produced in two ways: (a) withdrawal of essential fatty acid from the diet, and (b) exclusion of pyridoxine or thiamine from the diet or severe restriction of food (caloric deficiency).By the first method dienoic acid content of the tissues fell to lower levels, and typical symptoms of the deficiency were produced. By the second procedure, the fall was more rapid in the acute vitamin deficiencies but no symptoms characteristic of linoleic acid deficiency occurred. A similar but less rapid course was followed in caloric restriction.Since no essential difference in dienoic acid content of the tissues of rats was found under these several dietary conditions, it was concluded that pyridoxine under the conditions of these experiments does not exert a special supplementary action in the production or conservation of polyenoic fatty acids.     

The economics of reduced-rate insecticide applications to control aphids in winter wheat

Applications of pirimicarb and fenvalerate at full-rate and at a range of reduced dosages were applied on fields of winter wheat between 1983 and 1988 in West Germany. The relative effects of these treatments on the control of cereal aphids varied according to the growth stage at which spraying took place and the size of the aphid populations. The economic profitability of these treatments depended on the extent of post-treatment recovery of the aphid populations, the cost of control and the crop value. Under certain circumstances the high efficiencies of commonly-used insecticides at full dose-rate are not necessary to gain effective aphid control economically; a better return can be made by reducing the quantity of active ingredient per hectare.