Toxicity of Organic Phosphates to the Two-Spotted Spider Mite and the Foxglove Aphid

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Abstract
Low dosages of aerosols containing hexaethyl tetraphosphate, tetraethyl pyrophosphate, or tetraethyl dithiopyrophosphate in methyl chloride were more toxic to Tetranychus bimaculatus and to Myzus convolvuli than to Trialeurodes vaporariorum and to Pseudococcus citri. At dosages recommended for commercial greenhouses they were toxic to all 4 spp. Tetraisopropyl pyrophosphate and tetraethyl monothiopyrophosphate were equivalent to tetraethyl dithiopyrophosphate in their toxicity to 2-spotted spider mites and foxglove aphids. Tetraethyl pyrophosphate gave a max. kill of aphids and spider mites during the first 15 min. after release of the aerosol and began to lose its toxicity to aphids at the end of 30 min. and to spider mites after the 2d hour. Tetraethyl dithiopyrophosphate gave a higher speed of killing action and remained highly toxic to mites for 4 hrs. Aerosols containing octamethyl pyrophosphoramide applied to greenhouse crops gave slow but complete mortality of 2-spotted spider mites including the parathion-resistant strain and to 6 spp. of aphids. Octamethyl pyrophosphoramide was translocated to foliage from soil applications to a number of crops and from treated to untreated turnip leaves on the same plant.

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