Determinación de la Concentración Efectiva CE50 de Dos Plaguicidas Comerciales con Dimetoato como Ingrediente Activo sobre Plántulas de Lechuga (Lactuca Sativa, Fam Asteraceae) Variedad 'Batavia'

Abstract

The present work consisted in finding the effective concentration 50 (EC50) of two pesticides of different commercial house with the same active ingredient, Dimethoate belonging to the family of organophosphorus pesticides, on lettuce (Lactuca Sativa variety Batavia). The experimental design was based on Method 227 of the Organization for Economic Cooperation and Development (OECD) on Terrestrial Plant Testing: Vegetative Vigor Test; Which is designed to evaluate the effects on vegetative vigor of plants after exposure of the test substance. Two bifactorial (2x5) bioassays were performed using a randomized complete design, where the first factor is the insecticide brand (both insecticide A and insecticide B with 40% concentrated emulsion) and the second factor is the insecticide concentration. The first bioassay consisted in subjecting lettuce seedlings to different concentrations of the two insecticides (308,64 ml/L, 154,32 ml/L, 77,16 ml/L, 38,58 ml/L, 19,29 ml/L) and checking from which concentration there is a lethal response or a sub lethal response. From the results of the first bioassay the final assay concentrations were established. In the final bioassay lettuce seedlings were subjected to concentrations of 0.04 ml / L, 0.34 ml / L, 0.64 ml / L, 0.94 ml / L, 1.24 ml / L of insecticide A and concentrations of 0.08 ml / L, 0.91 ml / L, 1.74 ml / L, 2.57 ml / L, 3.4 ml / L of insecticide B. The response variables evaluated were the difference in length, root length, fresh weight and dry weight of the seedling at the end of the observation period. Measurements were taken for 28 days. For the leaf length and root length variables, no statistically significant differences were found, however, there were significant differences between the values of the dry weight variable for both pesticides. In addition, the results obtained in the preliminary bioassay were used to evaluate the percentage of individuals killed by the pesticide and the lethal concentration of both pesticides was found with ProStat software, resulting in values of 23,15 ml / L of Pesticide A and 46.66 ml / L of Pesticide B, for the main bioassay, the effective concentration for each variable was found by the same software. This process was made with both insecticides, A and B.