Characterization of impressions created by turfgrass arthropods on clay models

Lepidopteran pests such as Spodoptera frugiperda (J.E. Smith) (Noctuidae) and black cutworm, Agrotis ipsilon (Hufnagel) (Noctuidae) are serious problems of turfgrass in the U.S. Several predators that occur in turfgrass systems are capable of attacking larval stages of lepidopteran pests; however, their predaceous activity is rarely recorded, as they leave hardly any evidence of predation. Predaceous activity can be studied using clay models, but this approach is rarely employed in turfgrass. Regarding the utility of a clay model for studying predation in turfgrass, little is known about the types of impressions that common predators create on such models. Thus, laboratory assays were conducted to determine the types of impressions that common turfgrass arthropods leave on clay models simulating lepidopteran larvae. Nine impression types were characterized after exposing arthropods to the clay models for 48 h in enclosed arenas, including scratches, paired marks, pricks, deep distortions, disturbed surfaces, detached segments, granulated surfaces, dents, and elongated scratches. Most of the arthropods produced scratches and paired marks, whereas granulated surfaces and elongated scratches were produced by only a few of the selected arthropods. To ensure that the impressions were correctly identified, non-expert volunteers reviewed the impressions, and > 85% of the responses accurately identified the impressions as we had identified them. Knowledge of the impression types caused by common arthropods will improve the utilization of the clay model technique for field studies in turfgrass.