Influence of Abiotic Factors on Walking Behavior of Hunting Billbugs (Coleoptera: Curculionidae)

The hunting billbug, Sphenophorus venatus vestitus Chittenden, is an important insect pest of warm-season turfgrass. Larvae and adult S. venatus vestitus feed on turfgrass and affect normal grass growth and development. In sod farms and golf courses, management sprays are typically confined to affected areas because of the high insecticide and application costs. Understanding the walking behavior of S. venatus vestitus adults would help us to refine management tactics. Thus, the objective of this study was to determine the influence of abiotic factors on the walking behavior of adult S. venatus vestitus. A series of laboratory, semifield, and field assays were conducted in 2019 and 2020. For the laboratory assays, field-collected S. venatus vestitus adults were acclimated at 15, 18, 21, 28, and 32°C for 24 h, and the distances walked by these pre-acclimated adults were measured on sand and filter paper substrates using Noldus EthoVision XT software. For the semifield assays, the total and net distances walked by pre-acclimated adults were measured on a paved indoor surface. Sphenophorus venatus vestitus males and females moved farther when the temperature increased from 15 to 28°C in the laboratory and semifield assays. For the field assays, field-collected S. venatus vestitus adults were not acclimated. The total and net distances walked by the adults were documented on a paved surface. Increases in temperature and relative humidity did not affect the distance moved by adults, but an increase in wind speed reduced the distance moved.