UPTAKE, METABOLISM AND TOXICITY OF TERBUFOS IN THE EARTHWORM (LUMBRICUS-TERRESTRIS) EXPOSED TO COUNTER (R)-15G IN ARTIFICIAL SOILS

Earthworms (Lumbricus terrestris) were exposed to COUNTER(R)-15G in ar tificial soils for 32 d in four treatment blocks. Simulated rainfall a nd temperatures were used to approximate conditions during planting ti me in the U.S. corn belt. Maximum mean uptake of terbufos was noted on the 8th d following pesticide treatment. Terbufos sulfoxide uptake by earthworms was higher than terbufos uptake, and the concentration max imum was observed on day-16 post-application. Maximum concentrations o f terbufos sulfone were detected in earthworm tissues on day-32 post-a pplication. No significant earthworm mortality was observed on any sin gle collection date, but temporal differences in mortalities were note d between control and treatment groups. Total concentrations of terbuf os and oxidative metabolites in L. terrestris substantiate existing re sidue data from field investigations.