Seasonality and Adult Habitat Use by Four <i>Diabrotica</i> Species at Prairie–Corn Interfaces

Although Diabrotica pest species have been well studied in Þeld corn, Zea mays L., relatively little is known about adult habitat use by pest andnonpest species at prairieÐcorn interfaces. Therefore, the objective of this work was to compare seasonal patterns of beetles of four Diabrotica species and their use of remnant prairie and adjacent Þeld cornhabitats in southeasternNebraska. The study was conducted at Þve sites in 2001 and continued at three sites in 2002. TheDiabrotica species included D. barberi Smith and Lawrence, D. cristata (Harris), D. virgifera virgifera LeConte, and D. undecimpunctatahowardiBarber.Cucurbitacinvial trapswereused tomonitorDiabroticapopulations. Available ßowers and Diabrotica use of these ßowers were also documented. The virgifera group species(D.barberi,D.cristata, andD.v. virgifera)wereclosely tied toaprimaryhabitat, cornorprairie, but moved to secondary habitat if relative attractiveness of food sources in the primary habitat decreased; these three species had high initial population densities that decreased over the season. The one fucata group species (D. u. howardi) was found in various habitats, with low initial densities that increased over the season. Habitat type and contrasts in plant phenology seem to be key factors that inßuenced habitat choice by Diabrotica species; this especially affected the level of noncorn habitat use by pest species D. v. virgifera and D. barberi. Use of crop and noncrop parts of the agroecosystem by pest species suggests that a more holistic approach rather than a single Þeld view may be appropriate when managing corn rootworms.