Root Compensation of Seven Maize Hybrids Due to Western Corn Rootworm (Diabrotica virgifera virgifera LeConte) Larval Injury

M. IVEZICH1, E. RASPUDICH1, I. MAJICH1, J. TOLLEFSON2, M. BRMEZ1, A. SARAJLICH1 and A. BRKICH3
1 Josip Juraj Strossmayer University of Osijek, Faculty of Agriculture in Osijek, 31000, Croatia
2 Department of Entomology, Iowa State University, Ames, IA, 50011, USA
3 Agricultural Institute Osijek, 31000, Croatia

Abstract

IVEZICH, M., E. RASPUDICH, I. MAJICH, J. TOLLEFSON, M. BRMEZ, A. SARAJLICH and A. BRKICH, 2011. Root compensation of seven maize hybrids due to western corn rootworm (Diabrotica virgifera virgifera LeConte) larval injury. Bulg. J. Agric. Sci., 17: 107-115

The western corn rootworm is the major pest of maize in the USA, and from 1992 became major threat in Europe as well. During 2007, 2008 and 2009 field investigation was conducted in continuous maize to evaluate root injury and tolerance associated traits (root regrowth and root size) of seven commercial hybrids after rootworm larval feeding. Each year adult populations were monitored by pheromone traps that attract both males and females. The pheromone traps were monitored weekly. The greatest adult activity was recorded in 2008 with the capture of 9.60 beetles per trap per day. In 2007 and 2009, captures were 2.60 and 6.00 beetles per trap per day, respectively. Significant differences were observed every year among hybrids for all traits. All hybrids proved to be moderately tolerant to rootworm larval injury in the first year. Hybrid OsSK 602 was significantly different with the least damaged roots (an average root injury rating 1.24), good development of compensatory roots following larval root injury (an average root regrowth rating of 2.66), and this was the highest yielding hybrid. Hybrid OsSK 617 significantly differed as it was the most able to compensate rootworm larval injury with well developed new roots. Hybrids OsSK 602 and OsSK 617 had the best development of compensatory roots in the two years of continuous maize and can be considered as the most tolerant among the commercial maize hybrids evaluated.

Key words: Diabrotica, monitoring, root regrowth, root injury, tolerance
Abbreviations: WCR – western corn rootworm

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