Toxicity of Pesticides on Natural Enemies of Agricultural Pests

A simple, precise and economic method was developed to evaluate the residual toxicity of a pesticide to natural enemies. The highest commercial dose recommended by the manufacturer was sprayed on Petri dishes using a Potter tower or immersing the dishes in a diluted solution of the pesticide. The relative toxicity of a pesticide was compared using mean lethal time (TL 50 's) in 4 categories. The first category comprised the most toxic responses between 0h< TL 50 < 2h, and included: Azinphosmethyl on Neoseiulus chilenensis (Dosse) and Phytoseiulus persimilis Athias-Henriot; Chlorfenvinphos on Amitus spiniferus (Brèthes), Lysiphlebus testaceipes (Cresson), Pauridia peregrina Timberlake and Scutellista caerulea (Fonscolombe); Chlorpyrifos on A. spiniferus , L. testaceipes , Metaphycus flavus (Howard); P. peregrina and P. persimilis ; Diazinon on M. flavus and P. persimilis ; Esfenvalerate on P. persimilis ; Formetanate on Orius insidiosus (Say); Imidacloprid on A. spiniferus , L. testaceipes , M. flavus , P. peregrina , S. caerulea ; Methamidophos on O. insidiosus ; Methomyl on O. insidiosus ; Permethrin on N. chilenensis and P. persimilis . The second category consisted of TL 50 's between 2h< TL 50 < 5h and included: Chlorpyrifos on S. caerulea . The third category consisted of TL 50 's between 5h< TL 50 < 24h and included: Copper oxychloride on A. spiniferus and L. testaceipes . The fourth category consisted of TL 50 's after 24h>>TL 50 and included: Copper oxychloride on S. caerulea . The results of this study agree with those obtained by other researchers who used methods accepted by the International Organization for Biological Control of Noxious Animals and Plants (IOBC), which differ from the methodology utilized in this study. The results suggest that Lethal Time for 50% mortality is a quick, precise and economical method to establish the preliminary toxicity of a pesticide to natural enemies. Se desarrolló un método simple, preciso y económico para evaluar la toxicidad residual de los pesticidas, sobre adultos de enemigos naturales. Se aplicó la dosis comercial más alta recomendada por el fabricante, sobre placas de Petri en la Torre de Potter o por inmersión del sustrato en la solución del pesticida. La toxicidad relativa de pesticidas fue comparada en Tiempo letal medio (TL 50 ) en 4 categorías. La primera categoría comprende los de mayor toxicidad, correspondió a los TL 50 ubicados entre 0h