SIMAGRIO‐W: Development of a prediction model for wireworms in relation to soil moisture, temperature and type

As a result of increasing cultivation of corn and potatoes, the polyphagous larvae of the click beetles (Coleoptera: Elateridae), called wireworms, become a problem in agriculture (Parker and Howard 2001). The hypothesis that the vertical distribution of wireworms depends on soil moisture, soil temperature and soil type had to be verified. In field experiments, investigations on wireworm activity in relation to soil moisture and soil temperature were carried out over a period of 2 years. Bait traps were buried in soil, and the appearance of larvae was recorded during the seasons. In laboratory, the optimum soil moisture for larvae was tested with four soil types. Correlations between the percentage of observed wireworms and soil moisture were analysed. The results were taken as the basis for the prediction model SIMAGRIO‐W (SIMulation of the larvae of AGRIOtes (Wireworms)), which appraises the risk of damages on field culture caused by wireworms in relation to soil moisture and soil temperature. With logistic and Gaussian regressions, a first approach of a prediction model was developed. One output of the model displays the risk for damages in form of a binary response, which identifies two risk classes (risk and no risk). A second output displays for four soil types the percentage of appeared wireworms in relation to soil moisture, starting with an undefined amount of wireworms on a field. With a R² from 0.81 to 0.89, the percentage of occurred wireworms could be calculated well. The correlations were significant in all tested soil types (P ≤ 0.05). With data collected in 2010 and 2011, an independent validation was carried out to get information about the predictions quality of the developed model SIMAGRIO‐W. The hit rate was validated within two classes, risk and no risk. With correct results in over 85% of the cases, the class was predicted correctly.