EFECTOS DEL ETIL PARATHION Y DDYP SOBRE LARVAS DE CENTOLLA L IT H O D E S A N T A R C T IC U S JACQUINOT

Abstract

The tox icity o f two pesticides, ethil - parathion (DNTP) and DDVP, organophosphorous insecticides extensively used in commercial formulations, was evaluated. Standard short-term exposure (108 h) static toxicity bioassays were performed with Southern king crab larvae (1 st. zoeae) obtained from ovigerous females of Beagle Channel (Ushuaia). Each 12 h lethal concentrations for the 50% of the individuáis (LC 50) were estimated by Finney’s formal probit analysis. Three speed computing methods were used furthermore, obtaining not unbiased estimates in case of asymmetrical tolerance distribution. The data show that the two pesticides are acutely toxic at low concentrations. The 96 h of exposure LC50 are 33 /ag/1 for DNTP and 3.6 mg/¡ for DDVP. The DNTP toxicity curve indicates that lethal treshold concentration is smaller than 33 p.g/1. Apparently treshold for acute lethality were not found for DDVP.Both drugs induced suble'thal effects. There are: swimming and appendix inactivity, expansión of the posterior carapace area and rigid abdomen or eontinuously twisted.