Abstract

VECCO, Daniel; PINEDO, Román  and  FERNANDEZ, Miriam. Sampling methods for Pseudophilothrips sp. (Tubulifera: Phlaeothripidae) and its natural enemies: I. Enumerative sequential sampling. Rev. Protección Veg. [online]. 2015, vol.30, n.1, pp. 6-13. ISSN 2224-4697.

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.m^b-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=2,56m^1,50highly 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 E_50% 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=1,30m^1,09 highly significantly (p<0,000, R²=93,5%), with a tendency to a random spatial disposition (b»1). Sampling simulation showed the convenience of E_50% and E_30% when the individuals per plant were higher than 0,18 and 0,55, respectively. Sampling size was reduced in 40 ± 24% for E_50%. For natural enemies, binomial sequential sampling methods were suggested.

Keywords : thrips; inka peanut; Plukenetia volubilis.

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