Testing the suitability of simlep decision support system for protection of potato against colorado potato beetle (Leptinotarsa decemlineata [Say], Coleoptera, Chrysomelidae) in Slovenia

Abstract

In a period from 2007 to 2008 we studied the suitability of German decision support system SIMLEP, which was elaborated for protection of potato against Colorado potato beetle (Leptinotarsa decemlineata). In a field experiment in Ljubljana (Slovenia) we weekly assessed the number of egg clusters, young larvae (L1/L2), old larvae (L3/L4) and adults on 25 plants (5 places with five successive plants). The counting was performed between May 14 and August 6 2007 and between May 26 and August 4 2008. Model SIMLEP 1, which is used for a regional forecasting for the first occurrence of hibernating beetles and the start of egg laying, showed itself in both years as not suitable, while it forecasted the first occurrence of egg clusters 15 (2007) respectively 17 (2008) days too early. Model SIMLEP 3, a field-specific model which forecasts the occurrence of the developmental stages of Colorado potato beetle demonstrated as suitable. Namely, in both years this model very precisely forecasted the first occurrence of young and old larvae (in none of the cases the forecast differed from actual situation for more than 5 days) and also the occurrence of the highest number of egg clusters and young larvae (difference between forecasted and actual situation was from 0 to 7 days). With eventual future use of model SIMLEP 3 in Slovenia, a better effectiveness and economy in controlling Colorado potato beetle will achievable, by enabling us to define the optimum time of insecticide application. Model results may contribute to the reduction of pest resistance development to insecticides.