Improved Transect Sampling to Enhance Efficiency of Corn Rootworm Monitoring

Abstract

Crop monitoring for corn rootworm remains the best means to assess fields at risk from this pest if replanted to corn the following year. Use of sequential sampling reduced the minimum sampling time to about 20 minutes or less per field per visit to make a management decision. With previous funding from the NYSIPM program we developed a transect sampling protocol for sequential sampling that reduced sampling time by an additional 6 minutes per field. Our previous results were based on a relatively small number of fields (3) and simulations over a realistic but limited range of adult CRW spatial dispersion patterns. In this project we compared transect sampling to the commonly used systematic “W” system in 13 fields. Field trials using systematic, and transect sampling in each field were used to compare the categorization of adult corn rootworm densities into “above” or “below” threshold with a sequential sampling plan. Efficiency measured in time to reach a decision, number of corn plants evaluated, and time divided by plants observed were compared between sampling methods.