Seasonal and Regional Distributions, Degree-Day Models, and Phoresy Rates of the Major Sap Beetle (Coleoptera: Nitidulidae) Vectors of the Oak Wilt Fungus, Bretziella fagacearum, in Wisconsin

• DOI: 10.1093/ee/nvy080
• Publication Date: 2018-06-06T11:08:12Z
• Authors: Stephanie M Jagemann; Jennifer Juzwik; Patrick C Tobin; Kenneth F Raffa
• Keywords: Propagule; Limiting

Oak wilt is a lethal disease caused by the invasive fungus Bretziella fagacearum, which transmitted belowground via root grafts and aboveground sap beetles (Nitidulidae). Attempts to limit spread impact of B. fagacearum emphasize limiting harvesting pruning periods vector inactivity. However, there limited information on beetle activity periods, responses temperature, phoresy frequencies fungi. We sampled two major vectors in Wisconsin, Colopterus truncatus Carpophilus sayi, for 2 yr quantify their seasonal geographic abundances. Trapping was performed 12 oak stands, were assayed fagacearum. C. captured from March until November, peaking during April May. sayi May July. Relative abundances (N = 15,980) 59.3% 40.7% sayi. more abundant southern whereas evenly distributed. Both species present at asymptomatic sites. All sites with centers yielded viable fungal propagules, frequency association ranging 1 50%. Sites contained both species, but no vector-borne pathogen. Degree-day models constructed improve generality these results estimate cumulative emergences across latitudinal range over previous 10-yr means extremes. Because spans activities vectors, can help guide management practices.