Sampling Distributions and Sequential Sampling Plans for Eumargarodes laingi and Promargarodes spp. (Hemiptera: Margarodidae) in Australian Sugarcane

Abstract

Sampling statistics were determined for cysts of the margarodids Eumargarodes laingi Jakubski and Promargarodes spp. in sugarcane crops in southern Queensland, Australia. The Poisson distribution, Iwao's regression model, and Taylor's power law were used to determine the relationship between mean and variance of counts of both types of margarodids from sugarcane crops of different ages. All models indicated that the cysts were aggregated in distribution. Taylor's power law generally gave better or equivalent fits to the population dispersion parameters than did Iwao's regression model. Relationships to determine sample sizes for fixed levels of precision and fixed-precision-level stop lines for sequential sampling were developed for each margarodid genus. There were functional relationships between the variance and mean of untransformed population counts for all margarodids and crop ages, and the suitability of three transformation functions is assessed.