Development and usage of sequential sampling in an eggplant biological control intensive pest management program

Over a four year period (1988-1991), Colorado potato beetle eggmass, larvae and adult populations in 17 commercial eggplant fields were sampled twice weekly using a 100 plant fixed sampling program. Eggmass and adult/larvae (placed on an equivalent feeding basis) densities were determined. The spatial dispersion of eggmasses and combined motile forms was determined using Iwao's regression technique and Taylor's Power Law. Each technique described aggregated distributions for both eggmasses and combined motile forms. Taylor's Power Law, however, more accurately described Colorado potato beetle dispersion and was used as the basis for estimating optimal sample sizes and the creation of two sequential sampling plans, one for eggmasses (ET=1 eggmass/plant) and one for combined motile forms (ET=8 individuals/plant). The resultant plans were implemented in two commercial eggplant fields during 1992. Field verification showed a high degree of agreement between the decisions made by each plan and the densities determined from separate 100 plant samples.