Generalist Predators and Predation of Black CutwormAgrotis ipsilonLarvae in Close Mown Creeping Bentgrass

Abstract

Predators play a significant role in regulating pest outbreaks in turfgrass (Potter 2001). The most common predaceous arthropods recorded from turfgrass are spiders, predatory beetles (Carabidae and Staphylinidae) (Kunkel et al. 1999; Rothwell & Smitley 1999), predatory hemipterans, and ants (Lopez & Potter 2003; Frank & Shrewsbury 2004a). Natural enemies and their effects can be monitored by pitfall traps (e.g., Kunkel et al. 1999; Frank & Shrewsbury 2004a) or by exposing prey overnight without direct observation (Kunkel et al. 1999; Lopez & Potter 2000; Frank & Shrewsbury 2004a). Furthermore, most studies are conducted in roughs or fairways, which have more biodiversity (Lopez & Potter 2000), greater mowing height, and are less intensely managed than greens. Predation and predator abundance can be significantly different based on mowing heights (Rothwell & Smitley 1999). A better understanding of ecosystem services in putting greens may provide insights into reducing pesticide inputs. The objectives of this study were to determine the types of nocturnal predators in putting greens and determine which taxa are involved in predation of black cutworm larvae (Agrotis ipsilon Hufnagel) in close-mown bentgrass. Black cutworms provide a model system to investigate predation in turfgrass. Black cutworm larvae feed nocturnally on creeping bentgrass ( Agrostis stolonifera L.) greens causing pock marks that interfere with ball roll and aesthetics (Potter 1998). Predation trials were conducted at the Turfgrass Research Unit, Auburn, Alabama and the Grand National Golf Course, Opelika, Alabama. Plots or greens had not been sprayed with insecticides for at least 2 wk prior to each experiment. At the Turfgrass Research Unit, 2 plots of creeping bentgrass were used. A 706 m2 plot was used for larval predation trials, and a 929 m2 plot for predator surveys. Turfgrass in these plots was maintained at 0.33 cm with surrounding turf 2.54 cm high. Putting greens have 'Dominant' creeping bentgrass, whereas 'El Toro* zoysiagrass ( Zoysia japonica Steud), and 'Tifway' bermudagrass (Cynodon dactylon L. Pers Cynodon transvaalensis Burtt-Davy) were established in collars. Greens and collars are maintained at 0.36 and 1.27 cm, respectively. Larvae were obtained from a commercial in-