Sampling plans for spittlebug eggs in pastures of Brachiaria decumbens

Abstract

A sampling study of spittlebug eggs in pastures of Brachiaria decumbens was conducted by using a sample unit of 15 x 15 cm. The number of samples required for a certain level of precision was inversely proportional to population density. A crude estimate of number of samples necessary for 10, 15 and 20% of precision were 133,59 and 33, respectively. A study of sampling variation showed that differences between plots were much more important than the block differences; therefore plot to plot variation must be considered while sampling spittlebug eggs. The distribution pattern of numbers of eggs per 225 cm² of pasture fitted the negative binomial series. The sequential sampling plan presented here would reduce the sampling time over the conventional (fixed sample numbers) sampling.