SAMPLING ADULTS OF EOSCARTA CARNIFEX (HEMIPTERA, CERCOPIDAE) AND THEIR ASSOCIATED SYMPTOMS ON SUGARCANE

Sampling statistics were determined for adults of the froghopper Eosca rta carnifex (F.) and associated symptoms on sugarcane crops in northe rn Queensland, Australia. Samples using 10 consecutive stems per sampl ing unit minimized the variance:mean ratios for all sample sizes used to sample adults. The Taylor power law described the relationship betw een mean and variance of samples based on 10-stem sampling units bette r than did the Iwao regression model or the negative binomial model. A ll 3 models indicated that adults were aggregated in distribution. Rel ationships to determine sample sizes for fixed levels of precision and fixed-precision-level stop lines for sequential sampling of adults we re developed. There was a functional relationship between the variance and mean of untransformed froghopper counts, but this was eliminated by the Healy and Taylor transformation. Samples using 5 consecutive st ems per sampling unit minimized the variance:mean ratios for all sampl e sizes used to sample symptoms. The Iwao patchiness regression was th e only appropriate model for symptom data, and the slope indicated tha t damage is distributed uniformly between samples. Relationships to de termine fixed-precision-level stop lines for sampling of symptom data were developed.