Factors affecting bioactivity of soil insecticides: relationships among uptake, desorption, and toxicity of carbofuran and terbufos
1989
Felsot, A.S. | Lew, A.
Toxicities of insecticides applied to soil vary with soil type. The content of organic matter in soil seems to be most strongly associated with differences in toxicity. To test the hypothesis, that partitioning processes in soil influence toxicity by affecting the availability of the insecticides to the insects, we measured the uptake by southern corn rootworm, Diabrotica undecimpunctata howardii Barber, larvae of two concentrations of terbufos and carbofuran in four soil types. Desorption of the two insecticides from the soil into a calcium chloride solution also was determined. Concentration-response estimates for each insecticide were correlated with measurements of the uptake of the insecticides by larvae and the potential for desorption of the insecticide. Multiple regression analysis indicated that organic carbon content of the soil accounted for the greatest proportion of variability in LC50 and LC95. Uptake and desorption also were significantly correlated with organic carbon content. The data supported the role of partitioning in explaining toxicity of insecticides applied to soil.
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