THE INFLUENCE OF ABIOTIC FACTORS ON THE PRESENCE OF EUROPEAN CORN BORER (Ostrinia nubilalis Hubner)

Field experiments with natural population of European corn borer (ECB) were conducted in three vegetation seasons (2012-2014) at Agricultural Institute in Osijek. The experiment was set up in a randomized block design as split-split plot method, with three repetitions. This plot has been constantly maize - soybean rotation for already 15 years. It was a 3x3x4 factorial experiment with three irrigation levels (A1- non-irrigated (only natural precipitation), A2-from 60% to 80% field water capacity - FWC and A3-from 80% to100% FWC), three nitrogen fertilizer levels (B1-0, B2-100 and B3-200 kg N/ha) and four different genotypes (C1-0SSK 596; C2-0SSK 617; C3-0SSK 602 and C4-0SSK 552).The aim of this study was to determine the effect of different levels of irrigation, nitrogen fertilization and genotypes on occurrence and damage of maize plants by the European corn borer larvae and relation between leaf feeding larvae with nitrogen and silicon concentration as well as C/N ratio. At the end of each growing season, ten maize plants from each variant were cut. Ear weight for each specific plant (g), tunnel length (cm), number of larvae in stalk, number of larvae in the ear shank, ear shank damage (cm) and total number of larvae in maize plantwere determined. In silking stage (middle of July) ten leaves (below the ear), from 10 maize plants were sampled on each variant. Nitrogen, carbon and silicon concentrations were determined in maize leaf (%) and C/N ratio calculated. In 2014, a significantly lower ECB attack was determined taking into account lower temperatures and higher amount of precipitate compared to the previous years. Dominance of Z-type European corn borer on pheromone traps in the area of eastern Slavonia was confirmed. Increasing the level of soil water content, damage from larvae was reduced and increasing the level of nitrogen fertilization feeding activity was increased. We have confirmed different hybrid resistance in regards to damage from larvae, so C4 (OSSK 552) genotype was the most resistant while C1 (OSSK 596) was the most susceptible. Concentration of nitrogen and silicon in a maize leaf was in negative correlation as well as nitrogen concentration and C/N ratio. Hybrid resistance didn't entirely depend on nitrogen and silicon concentrations, even though there was greater damage on most hybrids with higher concentration of nitrogen, while damage was reduced with higher concentration of silicon.