Sequential sampling of Brachycaudus helichrysi (Homoptera: Aphididae) in sunflower fields

A sequential sampling plan for the leaf-curling plum aphid, Brachycaudus helichrysi Kaltenbach, on sunflower was developed using the fixed-precision method of Green. Our sequential sampling plan was validated using a resampling simulation approach with 5 independent data sets ranging in density from 5.8 to 188.2 aphids per sample unit. Sampling plans with a relative precision level of 0.30 were not recommended because of the low sample number and high variation that invalidated the normality assumption. Simulated results did not agree with the desired precision level for only 1 data set. This data set also deviated from our Taylor power law model. For the other data sets, simulated precision levels were generally better than the desired fixed levels. Variability of the B. helichrysi sequential sampling criteria was high for mean estimates and for the levels of precision