engleski

Natural occurence of Trichogramma wasps on European corn borer under different agricultural practices

The aim of this study was to determine the natural infestation of European corn borer (ECB) eggs by Trichogramma wasps (Hymenoptera: Trichogrammatidae) under field conditions. The experiment was duplicated for maize – soybean rotation. It was set by split-split plot method according to randomized block design in three replicates within a 1 ha field in Osijek, Croatia in 2013. The experiment included two levels of irrigations (A1-control, A2-60% to 100% field water capacity (FWC), A3-80% to 100% FWC), two nitrogen rates (B1-control, B2-100 kg N ha-1, and B3-200 kg N ha-1) and two maize genotypes (C1= OSSK 596 ; C3= OSSK 602). Parameters of ECB feeding activity and maize tolerance (cob mass, tunnel length, number of ECB larvae per plant), as well as number of parasitized ECB eggs by Trihogramma wasps were evaluated. The identification of Trichogramma wasps was made to genera.Genotypes were significantly different in terms of tolerance to ECB injury. Statistical analysis of data show higher resistance C3 than C1 genotype. In treatments with nitrogen fertilization, ECB feeding activity was increased at both nitrogen rates. Agricultural practices did not significantly affect parasitism of ECB eggs by Trichogramma wasps. Correlation between parameters of ECB feeding activity and parasitism by Trichogramma wasps was weak to moderate and not significant. Natural occurrence of Trichogramma wasps were not significantly affected by agricultural practices in maize, and population of this parasitoids was at low population to significantly affect ECB feeding activity.

Trichogramma wasps ; irrigation ; hybrid ; nitrogen fertilization

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