||Sublethal Neurotoxic Effects of the Fungicide Benomyl on Earthworms ('Eisenia fetida').
Callahan, C. A. ;
Drewes, C. D. ;
Zoran, M. J. ;
||Corvallis Environmental Research Lab., OR. ;Iowa State Univ., Ames. Dept. of Zoology.
Nervous system ;
Eisenia fetida ;
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Earthworms (Eisenia fetida) were treated by surface contact exposure for four days with the fungicide benomyl. Non-invasive electrophysiological recordings after treatment with sublethal concentrations of 0.2-25 mg benomyl/litre of water indicated concentration-dependent decreases in conduction velocity for the medial and lateral giant nerve fibers. Threshold concentration for these effects was approximately two orders of magnitude less than the LC50. The effects on velocity were not accompanied by alterations in refractory period or impairment of locomotory reflexes, but persisted for at least several weeks after treatment. It is concluded that benomyl had subtle and sublethal neurotoxic effects on earthworm giant nerve fibers.