Influence of insecticide treatments against the European corn borer (Lepidoptera: Crambidae) on the Incidence of Fusarium ear rot

Maize production is often threatened by numerous phytophagous insect species and diseases, among which the European corn borer (ECB) Ostrinia nubilalis and ear rot caused by Fusarium species stand out. The damage to maize ears caused by the European corn borer larvae can represent access points for Fusarium spores, increasing the probability of infection. The main objective of this study was to evaluate the efficacy of insecticide treatment against the European corn borer and its subsequent impact on reducing the incidence of ear rot caused by Fusarium species. Additionally, the study sought to assess the prevalence of Fusarium species throughout the four-year experimental period. The study was performed from 2013 to 2016 and included a treatment and a control, with four replications. Each experimental year, a combination of chlorantraniliprole and lambda-cyhalothrin at a recommended dosage was applied as an insecticide treatment, while in the control treatment no insecticides were applied. The obtained results indicated that the insecticide treatment significantly reduced the number of ECB larvae on maize ears in all years of the study, except in 2015. The efficacy of the insecticide treatment in reducing the total number of damaged ears was significant only in 2016, while in other years, the efficacy varied. The insecticide treatment had a significant effect on the disease severity index and significantly reduced ear rot only in 2013. During the four-year study, F. verticillioides was the most commonly identified fungal species on maize, except in 2014, when F. graminearum was dominant. The insecticide treatment had no effect on the species diversity within the Fusarium genus.