Model of Colorado potato beetle
Risk model For the calculation of the occurrence of the Colorado potato beetle we take into consideration: x) the duration of sunlight of the day (14 hours or 15hours of sunlight)
x) Soil temperature above 12°C
x) Average air temperatures during the last four days in combination with the day length give a value from 1- 4 (severity): 1= very low risk of colorado potato beetle 2= low risk of colorado potato beetle 3= average risk of colorado potato beetle 4= high risk of colorado potato beetle
The calculation of the risk is based on the detemination of the soil temperature and air temperature during a time period of the last 4 days. Soil temperature has to be above 12°C and in sum about 100800 degreeminutes (soil temperature * time) have to be reached to lead to beetle occurrence (basic condition for occurrence). Different severity classes are figured out (from 1- to 4, see above). On the graph you see that till the beginning of June the risk was 0 or very low. At the beginning of June conditions for the occurrence of the colorado beetle (more than 14/ 15hours sunlight and average air temperatures of 20-23 °C) have been good and a severity of 3, which means a moderate risk was determined.