Plano de amostragem convencional para trips na cultura do algodão

Abstract

Thrips of the species Caliotrips phaseoli and Frankliniella schultzei are considered to be pests of the cotton crop. According to Integrated Pest Management, the decision to control an insect pest must be made based on its population densities, which must be known through the adoption of sampling systems. However, there is no established sampling system for the thrips in the cotton crop. Thus, the objective of this research was to determine the sample unit, the sampling technique, the statistical frequency distribution and the number of samples to compose a sampling system. The experiment was conducted in 10 commercial farms located in the municipality of Pindaí, in the state of Bahia. The effectiveness of three sampling techniques was evaluated: leaf beat in white plastic tray, direct count of insects on the underside of leaves and beat cloth. Sampling time was recorded and cost, relative variance and economic accuracy were calculated for each sampling technique. It was found that the sampling of C. phaseoli and F. schultzei alone or added, should be performed with the beat of plants in white plastic tray. Once the sampling technique was selected, and using it, we returned to the field to determine the theoretical frequency distribution and the number of samples to compose the sampling plan. The sample data were adjusted to the negative binomial distribution and the number of samples to compose the sample system, at 15% accuracy, is 50.18 (approximately 51 samples) for F. schultzei and 44.07 (approximately 45 samples) for C. phaseoli + F. schultzei, which requires a sampling time of 0.28 hours and 0.50 hours, respectively, and are considered