Toxicity of pesticides to Allobophora caliginosa (Oligochaeta: Lumbricidae

Abstract

Juvenile (4-week-old) earthworms reared in a laboratory were kept individually for 7 days in soil treated with several concentrations of various pesticides. Mortality and weight change were recorded. The relative toxicity of each pesticide - i.e., the cOlicentration (mg/kg of dry soil) of pesticide causing zero growth - compared with the standard, carbofuran (0.10), was aldicarb (0.09), phorate (0.30), aldoxycarb (0.40), methomyl (0.54), ox amyl (0.59), isazophos (0.93), fenamifos (5.72), fensulfothion (7.35), diazinon (12.4), copper (106), and citowett (525). Field trial data from 33 published reports show similar relative toxicity results. The toxicity of carbofuran to Lumbricus rubellus and Allobophora caliginosa was similar. Decreasing concentrations of carbofuran caused mortality, suppression of growth, and suppression of egg capsule production in mature (clitellate) A. caliginosa collected from the field. The concentrations of carbofuran safe to juvenile and clitellate A. caliginosa were similar. Use of a single batch of natural soil, an artificial soil, or the silica powder and glass bead media used in one of the proposed EEC tests could reduce variation between tests. The latter media would provide the most standardised conditions for a toxicity test. Juvenile A. caliginosa which are easily reared would be a more appropriate species for the EEC test than Eisenia fetida. © 1986 Taylor & Francis Group, LLC.