Métodos de muestreo para Pseudophilothrips sp. (Tubulifera: Phlaeothripidae) y sus enemigos naturales: I. Muestreo secuencial enumerativo

El presente articulo es el primero de dos publicaciones que abordan el estudio de metodos de muestreo secuencial: 1) enumerativo y 2) binomial, para el monitoreo de Pseudophilothrips sp.y sus enemigos naturales. En el periodo 2007 - 2009 se realizaron 202 registros de poblacion en una parcela agroecologica de Plukenetia volubilis L. Se tomaron 10 hojas por tercio, 10 inflorescencias y 10 frutos, siguiendo un diseno sistematico aleatorizado. Las medias (m) y sus respectivas varianzas (s2) se ajustaron a la funcion de la Ley del Poder de Taylor (LPT) y se calcularon los limites de confianza del coeficiente de agregacion b para t 0,95. Adicionalmente, se propuso la simplificacion de la unidad de muestreo de trips. Se calcularon los tamanos de muestra n=E-2.a.mb-2; se disenaron cartillas de muestreo secuencial enumerativo y realizaron simulaciones que fueron comparadas con los registros para n=25. Las medias y las varianzas de Pseudophilothrips sp.se ajustaron a la ecuacion s2=2,56m1,50 en forma altamente significativa (p<0,000; R2=82,7%) y se confirmo su disposicion agregada . La unidad reducida de muestreo, constituida por frutos y hojas del tercio superior, se comporto como buen estimador de la poblacion total de trips (R2 = 94%). Se demostro la conveniencia del uso de los margenes de error E50% para evaluar bajas densidades y reducir el tamano de muestra necesario en 64 ± 16%. Las medias y las varianzas de la poblacion del complejo de enemigos naturales se ajustaron a la ecuacion s2=1,30m1,09 en forma altamente significativa (p<0,000, R2=93,5%), con una disposicion espacial tendiente al azar (b»1). La simulacion del muestreo demostro la conveniencia de E50% y E30%, a partir de 0,18 y 0,55 individuos por planta, respectivamente. El tamano de muestra se redujo en 40 ± 24% para E50%. Se sugirieron metodos de muestreo secuencial binomial, para el caso de los enemigos naturales. Palabras clave : thrips, sacha inchik, Plukenetia volubilis. Sampling methods for Pseudophilothrips sp. (Tubulifera: Phlaeothripidae) and its natural enemies: I. Enumerative sequential sampling ABSTRACT: The present paper is the first of two approaching the determination of sequential sampling methods, (1) enumerative and (2) binomial, for monitoring Pseudophilothrips sp . and its natural enemies. During 2007- 2009, a total of 202 population samplings were carried out in an agroecological plot of Plukenetia volubilis L. Initially, ten leaves per each of the three plant thirds, ten inflorescences and ten fruits were taken. The means (m) and their respective variances were adjusted to the function of Taylor‘s Power Law (TPL), and the confidence limits of the aggregation coefficient b were calculated for t 0,95. Additionally, simplification of the sampling unit of thrips was proposed. Sample sizes were calculated by n=E-2.a.mb-2; primers for the enumerative sequential sampling were designed, and simulations compared with records for n=25 were carried out. The means and variances of Pseudophilothrips sp . fitted to the equation s2=2,56m1,50highly significantly (p<0,000; R2=82,7%), and the aggregated disposition of the thrips was confirmed. The reduced sampling unit, composed of fruits and leaves of the higher plant third, performed as a good estimator of the total population of thrips (R2 = 94%). The use of the error margins E50% was shown as convenient for evaluating low densities of thrips and reducing the necessary sampling size in 64 ± 16%. Means and variances of the population of the complex of natural enemies fitted to the equation s2=1,30m1,09 highly significantly (p<0,000, R2=93,5%), with a tendency to a random spatial disposition (b»1). Sampling simulation showed the convenience of E50% and E30% when the individuals per plant were higher than 0,18 and 0,55, respectively. Sampling size was reduced in 40 ± 24% for E50%. For natural enemies, binomial sequential sampling methods were suggested. Key words : thrips, inka peanut, Plukenetia volubilis.