J. IGRC BARCIC, R. DOBRINCIC, M. MACELJSKI
Faculty of Agriculture, Department of
Agricultural Entomology, Svetošimunska 25, 10000Zagreb, Croatia; mail:
jigrc@agr.hr , tel. 385 1 2393-804
The occurrence of Diabrotica virgifera virgifera LeConte in Croatia was registered in 1995. In the year 2000 WCR was spread on a 14,000 sqkm area. Of that area, there was about 700,000 ha of arable land on which 200,000 ha of corn was sown.
The Department of Agricultural Zoology, Faculty of Agriculture Zagreb has carried out nation-wide survey of Western Corn Rootworm (Diabrotica virgifera virgifera LeConte) in Croatia since 1995.
As in previous years, pheromone and Pherocon AM traps were provided through FAO WCR Network.
The traps were placed out on 145 sites and 75 monitor were involved in the monitoring action. On each site 1 pheromone and 1 Pherocon AM trap were placed 50 m apart. Traps were placed in the field on June 27th. Each 7 days the traps were checked and beetles collected. Fifty five sites (38%) were located at the infested regions, 48 sites (33%) along the line of spread in 2000, and 42 (29%) within uninfested areas. Ten monitoring sites are the permanent ones.
The first catch on pheromone trap was registered on June 28th. Before disposing all results on 130 monitoring sites 16,353 beetles were caught. Most of the beetles were caught on pheromone traps. The maximal catch, 62.5% of all caught beetles were caught between July 10th and August 10th.
The WCR population density varied from locality to locality, we evaluate that the increase factor in the earlier infested area for 2001 is between 1.5 and 2.5. The data from 10 permanent monitoring sites confirms that statement.
Only on one monitoring site located outside of the area infested in 2000 one WCR male was caught until now. We can state that in 2001 WCR spread toward west (60km) to the village Dubrov?ak Lijevi. This spread occurred along the river Sava. No spread along the river Sava was registered in 2000. No further spread along the river Drava and the Hungarian border was recorded until now.
Three monitoring sites were located around the International Airport Zagreb. WCR has not been found on any of these traps.
In 2001, corn roots in the soil insecticide trial in Tovarnik were dug and evaluated for WCR damage. Plants in a few continuos corn fields in the region Baranja were also evaluated. The average root rating in untreated plots in soil insecticide trial was between 2.5 and 3 (same as in 1999). In some inspected fields in Baranja we found lodged plants. The average root rating in these fields was between 3.5 and 4.0. In one seed corn field a high adult population and the silk damage were registered. The yield loss will be established.
Altogether, in 2001 an area of approximately 15,500 km2 is infested with WCR, in which area approximately 220,000 ha of corn is grown.
Further spread and an increase in the root damages in 2002 are expected.