Population dynamics of western corn rootworm (Diabrotica v. virgifera) in Slovenia | Populacijska dinamika koruznega hrosca (Diabrotica v. virgifera) v Slovenji

The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte (Coleoptera, Chrysomelidae), is a non-native insect species in Europe. In Slovenia it was first identified in 2003. The outbreak and spreading of the species was determined in frame of a systematic surveillance using PAL pheromone traps and yellow sticky traps. In 2005, KLP trap baited with the floral bait, which also attract females were placed on the locations in Pomurje and Podravje. The outbreak of WCR was also monitored in pumpkin plantations (Cucurbita pepo L.) using pheromone traps and the control of blossoms. The first 19 specimens of the species were caught with PAL traps in Pomurje and Podravje near the border with Hungary and Croatia and in the area of northern Primorska (Coastal region) near the Slovene-Italian border in 2003. While in the period 2003 - 2006 the population of WCR in Primorska did not increase the number of WCR caught in the attacked areas of NE Slovenia in 2006 reached the total number of 4082. From 2003 on the pest has spread in Slovenia gradually towards the interior of the country and in 2006 it reached the wider area of the valley Savinjska dolina, i.e. more precisely the environment of Dramlje. At the time of WCR outbreak more females than males were caught on the average using KLP flor traps. The first specimens of WCR by means of yellow sticky traps were caught in 2005 at the borderland with Hungary (2 beetles/yellow sticky trap/week). Also, in 2006 the catch remained pretty much the same so that the economic damaging level had not been exceeded. In the pumpkin plantations the adult specimens were caught for the first time in 2004 by means of pheromone traps, and two years later the WCR were found directly in pumpkin blossoms by visual observations. Within the previous monitoring of WCR outbreak it was established that the first specimens appear each year in the second week of July while the peak of outbreak occurs at the beginning of August. The WCR were observed on individual fields up to the month of October.