Spatial dispersion and binomial sequential sampling for the potato psyllid (Hemiptera: Triozidae) on potato.

BACKGROUND The potato psyllid is a serious pest of potatoes. Sampling plans on potatoes for the potato psyllid have yet to be developed, thus the authors' objectives were (1) to determine the most efficient within-plant sampling unit, (2) to determine the spatial dispersion of potato psyllids in potato fields and (3) to develop a binomial sequential sampling plan for this pest. RESULTS Significantly more potato plants were infested with potato psyllids on the edges of the field, and significantly more plants were infested with psyllids on the 'top' and 'middle' of the potato plant. Significantly more psyllids were also found on the undersides of leaves. The potato psyllid has an aggregated distribution in potato fields. Binomial sequential sampling plans were developed for three action thresholds representing 0.5, 1 and 5 psyllids per plant. The average sample numbers for these action thresholds were between 12 and 16 samples, depending on the action thresholds. However, based on the shape of the operating characteristic curve, the 0.5 and 1 sampling plans were more reliable than the 5 psyllids per plant plan. CONCLUSION The binomial sequential sampling plans are useful for detecting potato psyllids at low levels of infestation, which will be useful for pest management purposes.