Distinguishing Friend from Foe: Identification of Beetle Pests on Turfgrass in Southern Arizona

Abstract

To maintain a visually appealing and playable condition, golf courses require monitoring and management of insect turfgrass pests. In the United States, the most common and damaging pests are the larvae of several scarab and hybosorid (Scarabaeoidea) beetle species (Scarabaeidae and Hybosoridae). Even though the golf industry in Arizona annually contributes $6 billion to the state economy, turfgrass pests are understudied in the state. We sought to first determine which species damage turf in Arizona and then determine the time of year each species is most active. Larvae were collected from square-foot soil core samples from areas displaying soil damage that could be attributed either to vertebrate digging/pecking activity and/or direct root feeding activity. Adults were collected using black light bucket traps, set nightly from May 1 to August 20, 2022. Adults were first identified with dichotomous keys and thorough comparison with expertly identified specimens in the University of Arizona Insect Collection. We also used DNA sequence data from cytochrome oxidase 1 (COI) to associate adults and larvae of the same species and to molecularly confirm species identifications using the Barcode of Life Database. Of the species collected in light traps during this study, we found three species damaging turfgrass in Arizona: Cyclocephala pasadenae (BOLD:AAY5363), Hybosorus illigeri (BOLD:AEV9441, BOLD:AAH0353), and Ataenius stephani (BOLD:AEU2777). Peak flight activity of these species varied but all occurred between June 26 to August 10. This research provides a crucial baseline to inform future research on best practice management strategies for turfgrass managers in southern Arizona.