Seasonal Abundance and Spatial Distribution of Wireworms (Coleoptera: Elateridae) in Georgia Sweet Potato Fields

Abstract

Seasonal abundance and spatial distribution of Conoderus wireworms were studied in sweet potato fields in Georgia. Wireworm numbers were highest in July and decreased successively thereafter in the two fields sampled for wireworm abundance. Spatial distribution was determined by comparing data for fit to six mathematical distributions (Poisson, Poisson with zeros, negative binomial, Thomas double Poisson, Neyman’s type A, and logarithmic with zeros). Data collected from seven fields were described using Taylor’s power law and Iwao’s regression techniques. Wireworm distribution was clumped at the beginning of the season at least in O.10-ha plots and became random thereafter. The spatial distribution of C. rudis (Brown) was aggregated (Taylor) and random (Iwao), whereas C. scissus (Schaeffer) and C. amplicollis (Gyllenhal) distribution was mostly aggregated and random, respectively. Small larvae of C. scissus were regular in distribution, whereas distribution of medium and large larvae was mostly random and aggregated, respectively. The general pattern of wireworm distribution was random as obtained from seven fields. Optimum sample size required for a 2.0-ha area for reliable estimate of wireworms in economic management level (40%) was 57, 33, and 19 at 0.5, 1.0, and 2.0 wireworms, respectively, per sample.