Sampling Methods and Spatial Distribution Patterns for Threecornered Alfalfa Hopper Nymphs (Homoptera: Membracidae) on Soybean

Estimates of Spissistilus festtnus (Say) nymphal populations in soybean by ground-cloth, ground-cloth plus plant-base inspection, and whole-plant inspection methods were compared with absolute estimates obtained by bagging plants. Spatial distribution patterns were described by Taylor’s power law for each sampling method. Whole-plant inspection was the most suitable method because of the high fidelity of its population estimates to absolute estimates and the absence of marked age-class bias. Both ground-cloth methods exhibited severe age-class bias, detecting late instars much more effectively than early instars, and gave lower population density estimates than the other methods. The value of the groundcloth methods as research sampling tools for S. festinus nymphs is questionable. Parameters for Taylor’s power law were influenced by sampling method, sample size, and instar. Wholeplant inspection yielded parameter estimates that were most readily interpretable in light of previously reported aspects of S. festtnus . biology.