Management of western corn rootworm (Diabrotica virgifera virgifera)

Abstract

Western corn rootworm (WCR) was registered for the first time in Europe near the Surcin international airport in Serbia in 1992. The spread of WCR on the territory of Serbia and its population density increased fast. The Serbian territory was entirely populated in the following few years, while major damages occurred on corn grown for two or more years in the same field. Data on damages caused to over 140,000 ha under corn until 1999 were collected by organized monitoring. After 2000 and 2003, population abundance of D.v. virgifera, as well as the number of damaged corn fields, significantly decreased due to drought and application of crop rotation. Corn rootworm has one generation per year. It overwinters in the egg stage. Under the climatic conditions of Serbia larvae hatching starts around May 15th. The highest number of larvae on root is observed around June 20th when feeding is most intensive and plants become lodged as they lose roots. First adults emerge by the end of June. Their abundance increases during July and reaches maximum by the end of the month. From the second decade of August the abundance decreases. Adults are present in the field until the first frosts. Larvae are much more harmful and significant than adults. Larvae feed on roots or into roots by boring. Roots can be entirely destroyed under heavy attack and the host plants lodged already at the end of June. Under our climatic and agrotechnical conditions, adults are sporadic pests. Adults are a threat only when sowing is done after the optimal sowing date or in case of stubble corn sowing. Crop rotation is an efficient and most widespread means of WCR control. No damage on corn grown in crop rotation has been registered in Serbia for now. In the first year of production corn does not require protection from Diabrotica virgifera virgifera LeConte larvae. Several insecticides have performed high efficacy by application at sowing and have been registered for commercial use. On the other hand, soil insecticides have never been applied on a significant area in Serbia.