Abstract

SALVIO, Carla; MANETTI, Pablo Luis; CLEMENTE, Natalia Liliana  and  LOPEZ, Alicia Noemí. Scarítes anthracinus (coleoptera: carabidae): efecto tóxico de clorpirifos y de cipermetrina en bioensayos de laboratorio. Cienc. suelo [online]. 2015, vol.33, n.1. ISSN 1850-2067.

Carabid predators are mainly located on the soil surface and they are exposed to the negative effects of insecticides. The aim of this study was to evaluate the effect of Chlorpyrifos and Cypermethrin on Scarites anthracinus (Coleoptera: Carabidae). Two bioassays were conducted separately using different doses of Chlorpyrifos (emulsifiable concentrate (EC), 48% active ingredient (a.i.)) and Cypermethrin (CE, 25% a.i.). Each experimental unit consisted of a container filled with 500 g of wet soil and 24 g of vegetal residue where one individual of S. anthracinus was placed. In the Chlorpyrifos bioassay treatments were 0; 24; 48; 120; 240; 480; 960 and 1440 g of a.i. ha^-1 while in the Cypermethrin biassay rates were 0; 12.5; 25; 50; 75 and 100 g of a.i. ha^{-1. A complete randomized experimental design with 12 replicates was set up. Containers were placed in a chamber at 20 ± 2 °C and 14L: 10O. The proportion of dead individuals increased as doses of both insecticides raised. Using a rate of 120 g Chlorpyrifos ha-1} 100% mortality at 120 hours after application was achieved and its median lethal dose (LD₅₀) was 60.44 g a.i. ha^-1. On the other hand, the highest proportion of dead individuals (i.e. 0.6) was achieved using a rate of Cypermethrin of 100 g of a.i. ha^-1 and LD₅₀ was 99.52 g of a.i. ha^-1. Chlorpyrifos was very toxic to S. anthracinus because population was reduced to a half by using a dose less than 8 times the recommended for production. Cypermethrin was less harmful since LD₅₀ was only twice the recommended dose.

Keywords : Carabid; organophosphate; pyrethroid.

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