Validation of phenology models for Halyomorpha halys (Hemiptera: Pentatomidae) using field data from climatically different ecoregions.

Halyomorpha halys (Stål), an invasive species of Asian origin, has become a key pest of tree fruit in areas of the Eastern and Pacific Northwest United States. This study used a 5-yr dataset of pheromone trap captures from 4 ecoregions (Mountains, Piedmont, Southeastern Plains, and Atlantic Coastal Plain) of North Carolina to validate temperature-driven phenology models previously reported for oviposition by overwintering adults and eclosion of F1 adults using semi-field cage studies. Cumulative proportion of pheromone trap captures of F1 adults and nymphs over cumulative degree days was compared to predictions based on the previously reported models' quadratic equation curves for adult eclosion (y = -0.0000015x2 + 0.004736x - 2.664) and oviposition (y = 0.0000032x2 - 0.010853x + 9.050). The oviposition model was validated using projected oviposition curves to predict nymphal populations over time by using life stage-specific development and mortality rates. Analysis of coefficients of determination (R2) for all regressions showed that F1 adult model predictions varied by region and year. Mean R2 values in the Mountain, Piedmont, and Southeastern Plains ecoregions for F1 adults were 0.88, 0.93, and 0.93, respectively. Nymphal regressions also varied by ecoregion, with mean R2 values of 0.95, 0.86, and 0.88 in the Mountains, Piedmont, and Southeastern Plains, respectively. Differences among regions were mostly associated with lower R2 values at sites with low population densities. Results are discussed in relation to the value of these models in studying the ecology of invasive species and in informing pest management decisions.