[The use of scales to estimate tetranychid mites in cassava]

anglais. We determined the relationship between a population scale used in the field and direct counts of tetranychid mites in the laboratory. We also determined the stability of the scale in different plant strata. The data were collected during two crop cycles at CIAT Palmira, of the cassava clone CMC-40. Counts were made every two weeks in 20 plots of 144 plants each. A central plant was chosen and every other leaf after the first completely developed leaf was sampled. Phytophagous mites were counted on individual leaves from 5 randomly selected plants under a stereo-microscope, discriminating mobile stages and species. All phytoseiid mites present were counted collected and identified in order to determine their within-plant distribution.

espagnol; castillan. El estudio se desarrollo durante dos ciclos de cultivo en el CIAT-Palmira con la variedad CMC-40 y para ello se hicieron muestreos quincenales de 20 parcelas de 144 plantas cada una, escogiendo una planta central y colectando una hoja de por medio a partir de la primera completamente desarrollada. En hojas individualizadas de 5 plantas al azar se realizo bajo el estereoscopio, el recuento discriminado por estado movil y por especie de los fitofagos. Se colecto la totalidad de los fitoseidos por cada nudo evaluado para establecer su distribucion vertical en la planta. Se lograron definir los coeficientes que permiten convertir la calificacion de campo, en estimaciones de las poblaciones reales para acaros Tetranychidae en yuca y se establecieron los limites de confiabilidad del sistema de muestreo.