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TERATOGENIC EFFECTS OF THE FUNGICIDE BENOMYL ON POSTERIOR SEGMENTAL REGENERATION IN THE EARTHWORM, 'EISENIA FETIDA'
Citation:
Zoran, M., T. Heppner, AND C. Drewes. TERATOGENIC EFFECTS OF THE FUNGICIDE BENOMYL ON POSTERIOR SEGMENTAL REGENERATION IN THE EARTHWORM, 'EISENIA FETIDA'. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-86/411.
Description:
Earthworms, Eisenia fetida, were treated by surface exposure to the fungicide benomyl at various stages of posterior segmental regeneration. Teratogenic effects of benomyl were observed when worms were treated 7-11 days after amputation (i.e. during the normal period of segmental replication), but not during days 1-5, 13-17, or 19-23. Teratogenic effects included a reduction in the number of regenerated segments, an increased frequency of segmental groove anomalies, and a variety of monstrosities. The effects of benomyl treatment on the number of regenerated segments and frequency of anomalies were dose-dependent within a narrow concentration range (approximately 0.2-5.0 mg liter-1); at higher concentrations (e.g. 25 mg liter-1) teratogenic effects were less frequent because the onset of segmental delineation was delayed until well after exposure. Non-invasive electrophysiological recordings from treated worms indicated that functional integrity of giant nerve fiber conduction pathways was established in all anomalously regenerated tail segments, except in a two-tailed monstrosity. The evidence supports the hypothesis that these teratogenic effects derive from an antimitotic mode of action of benomyl on segmental regeneration. (Copyright (c) 1986 Pesticide Science.)