• Comparative Analysis of Two Sampling Methods for Estimating Abundance of Adult Bemisia tabaci in Cotton

      Naranjo, S. E.; Flint, H. M.; Henneberry, T. J.; Silvertooth, Jeff; USDA-ARS, Western Cotton Research Laboratory (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      The leaf turn method and the black pan method, two sampling methods for estimating the abundance of Bemisia tabaci (Strain B) on cotton, were compared over a two year period in Maricopa and Phoenix, AZ Both methods were highly correlated with the density of immature stages prior to the use of insecticides, but more poorly correlated after insecticide use began. The two methods were highly correlated with one another, however, leaf turn counts were better predictors of immature infestation. The leaf turn method was also much less variable between individual samplers than the black pan method. Finally, in terms of cost-efficiency it takes, on average, 71% less time to estimate population density with an acceptable precision using the leaf turn method. Based on these criteria, the leaf turn method is a more reliable and efficient technique for estimating adult abundance.
    • Evaluation of a Leaf-turn Method for Sampling Whiteflies in Cotton

      Diehl, J. W.; Ellsworth, P. C.; Naranjo, S. E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Plans for sampling sweetpotato whiteflies in cotton were evaluated within 8,000 acres of cotton within central Arizona. These plans were found to be a practical and efficient way to track whitefly populations. In general they should add about 8 minutes to a pest sampling regime. Neither time of day nor sampler experience were found to have a significant effect on the number of whiteflies counted. Therefore, this method provides a common currency for growers, PCAs and others to compare whitefly numbers among fields and through time.