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Abstract
The billbugs, Sphenophorus spp. (Coleoptera: Curculionidae), are important pests attacking turfgrass. Evaluation of linear pitfall trap captures revealed Sphenophorus venatus vestitus as the major billbug species (> 98%) in the sod farms of central Georgia. Also, seasonal billbug captures were influenced by turfgrass phenology (e.g., early and late growth stage and fully grown turfgrass). The numbers of Sphenophorus spp. collected were significantly greater in the fully grown turfgrass than in the early- and late-growth stages. Adult billbugs were sampled from harvested and nonharvested areas of sod farms by using linear pitfall traps. A significantly greater number of billbug adults were captured from the nonharvested than from the harvested sod. Sphenophorus spp. adults actively emerged from the harvested and nonharvested sod areas. A series of laboratory, semi-field, and field assays were conducted to determine the influence of abiotic factors on the walking behavior of adult S. venatus vestitus. S. venatus vestitus males and females moved further when the temperature increased from 15 to 28 °C under laboratory and semi-field assays. The increase in temperature and relative humidity did not affect the distance moved by adults in the outdoor assay, but the increase in wind speed reduced the distance moved.
The spatial distribution patterns of S. venatus vestitus larvae and adults were analyzed at four sod farm sites in central Georgia using SADIE and variograms. Analyses revealed a significant aggregation pattern for adults, whereas aggregated distributions were detected for larvae with variogram analyses. The average ranges of spatial dependence for larval and adult samples were 3.9 m and 5.4 m, respectively. A survey was conducted to determine the major pests and current management practices in the commercial turfgrass industry. Most golf courses, and sod farms respondents identified fall armyworm, white grubs, and mole crickets as major pests than billbugs, chinch bugs, and others. Also, respondents use insecticides multiple times a year and indicated that management of the major pests is driven mainly by insecticide use.