engleski

Corn hybrids tolerant to Corn Rootworm (Diabrotica virgifera virgifera LeConte) larval feeding

Western corn rootworm (Diabrotica virgifera virgifera LeConte (WCR) is known as a economic pest of corn in the USA. In the USA, insecticides are regularly used to control WCR, but the cost is high, can pose environmental risks, and may become ineffective due to resistance. As a new corn pest in Europe WCR was recorded 1992 in Serbia and pest arrived in Croatia in 1995. Investigations on resistance to western corn rootworm (Diabrotica virgifera virgifera LeConte) began over 60 year ago. Growing corn resistant to corn rootworms would be a valuable alternative to insecticides. The aim of this investigation is find out more tolerant corn hybrids to larval feeding. Ten Croatian (Institute of Agriculture, Osijek) and two Pioneer Hybrid Inc. (Johnston, Iowa, USA) commercial corn hybrids were evaluated for WCR resistance at four locations using a randomized block design with four replications. Two locations were in east Croatia (Gunja, Osijek) and two were in the USA (Iowa, Missouri). At the Missouri location the plots were artificially infested with WCR eggs ; the others contained natural rootworm infestations. At all locations, root injury was rated using the Iowa State University Node-Injury Scale (0- 3) and the hybrids’ tolerance to larval feeding was compared by evaluating root size and root regrowth. In an analysis of variance combined across locations, root injury, size and regrowth were significantly different among hybrids and there was a significant location by environment interaction for each response variable. Root injury ratings in the USA were higher than in Croatia. Analysis by location showed the hybrids differed significantly in root injury, root size, and lodging at Croatia and USA side. Growing hybrids more tolerant to WCR does not eliminate corn rootworm, but it could reduce the amount of insecticides that needed to be applied.

corn ; WCR ; tolerant hybrides

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