Damage determination of western corn rootworm(Diabrotica virgifera virgiferaleconte) in soil disinfected, continuous corn

Abstract

Introduction Corn is one of the most important cultivated plants of Hungary (Varga and VargaHaszonits 2003), for the last years its sowing area can be said unchanged ranging from 1.1-1.2 million ha. In the last decade its yield per ha increased considerably, between 2003 and 2005 the average quantity of corn harvested on one ha was 7.52 t and the total corn yield of Hungary surpassed 9 million t (Hingyi 2006). Easy to see that disclose the biotic yield decreasing factors of this economically important crop is an essential task. The success of corn production in Hungary is fundamentally determined by the American origin invasive western corn rootworm (WCR). Since its first Yugoslavian description in 1992 (Baca 1993) the pest has extremely rapidly spread and settled in Europe. According to a survay made in 2004 the species has caused economic losses in an area of 300000 km 2 in Europe (Ripka 2004). The successful European acclimatization of the pest can be explained partly by the soil cultivation base of crop production (Bayar et al. 2003, Jug et al. 2006), partly by the optimum Middle-European climatic conditions required for its development and spreading (Ilovai et al. 1998). The WCR’s damage in the field may show a wide range from a 100% yield loss due to a total lurch to the economically negligible leaf peeling (Ivezic et al. 2006, Hatalane Zseller et al. 2004). The manifestation of these symptoms in a given area is greatly influenced by the pressure of the pest (Keszthelyi 2005), the actual annual precipitation conditions (Hadi 2004, Riedell 1994) and the agrotechnical operations of the corn field (Hatalane Zseller et al. 2004), However, it can be declaired that without soil disinfecting insecticides used in the case of monocultures successful corn production is today is almost unimaginable (Little et al. 1992).