Western corn rootworm control in Switzerland, yet a successful story

Since 2000 Switzerland belongs to the 22 European countries where the quarantine pest Diabrotica virgifera virgifera LeConte, Western corn rootworm, has been detected. It’s reported to be the most important maize pest worldwide with an economical damage up to 1,5 Billion $. In Switzerland, it’s constantly present in the southern part of the Alps, while few beetles are sporadically found in the northern part. Observations during 12 years allowed to determine that the populations in the southern part of the Alps are generated by yearly migrations from the principal foci of neighbored Lombardy. The correlations referred to space and time versus the distance to the south border are hardly leaving doubts. Control measures enacted by Swiss authorities were principally based on a severe crop rotation without the use of chemicals as in the European Union. The effect of crop rotation has been tested in a 5 year field trial. Results showed that no economic population has been built up during this period in the crop rotation treatment, confirming observations of the actual practice.