Absolute Sampling Technique for Corn Rootworm (Coleoptera: Chrysomelidae) Adult Emergence that Adjusts to Fit Common-row Spacing

An absolute sampling technique for northern and western corn rootworm, Diabrotica barberi Smith and Lawrence (NCR) and D. virgifera virgifera LeConte (WCR), respectively, adult emergence was developed that could be used in cornfields of different inter-row spacings. The sampling technique was used in 12 commercially grown cornfields from 1979–1983 to obtain estimates of sampling variability. The optimum sampling scheme for emergence of NCR and WCR field populations involved sampling at a single site within each of a large number of quadrats located throughout the field. Sample sizes needed to obtain an estimate with a standard error within 10% of the mean for WCR and NCR are 80 and 222, respectively.