Abstract

RICARDO, Tamara; MAITRE, Maria Inés  and  RODRIGUEZ, Alba Rut. Sublethal effects of lambda-cyhalothrin on Eisenia fetida (Annelida, Oligochaeta, Lumbricidae). Cienc. suelo [online]. 2010, vol.28, n.1, pp.39-46. ISSN 1850-2067.

The intensive use of agrochemicals has deleterious effects on non-target organisms. Among these organisms, earthworms are important because of their role in keeping the soil structure and fertility. Lambda-cyhalothrin is one of the most widely used pyrethroid insecticide in Argentina, but there are not enough studies of the effects of this pesticide on earthworms. The goals of this work were to perform chronic toxicity bioassays to determine the effects of commercial lambda-cyhalothrin (at 5%) on Eisenia fetida. The parameters of behaviour, survival, biomass, reproduction, bioaccumulation and the degradation time of lambda-cyhalotrin in an OECD standard soil were also estimated. Results showed a hard avoidance behaviour in the lowest lambda-cyhalothrin concentration with an EC₅₀ of 1.36 mg kg^-1 (95% C.L 0.24-2.80). Eisenia fetida chronic test survival and feeding were not affected by lambda-cyhalothrin but negative effects on reproduction were significant (P<0.05). Cocoon production and fertility were reduced and incubation time was incremented. The BAF were between 0.005 and 0.08 in the test concentrations and the soil degradation of lambda-cyhalothrin was complete after 86 days.

Keywords : Pesticides; Soil fauna; Toxicity; Bioassays; Insecticides.

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