Managing fumonisin contamination in maize kernels through the timing of insecticide application against European corn borer

European corn borer (ECB), Ostrinia nubilalis, is the main maize pest in Central and South Europe and it has been shown to promote Fusarium verticillioides infection in maize grains, a well-known fungal producer of fumonisins. Field experiments were performed in 2006 and 2007 in two sites in NW Italy in order to determine the effects of the timing of insecticide applications on maize on ECB damage, fungal ear rot and fumonisin contamination in naturally infected conditions. Different insecticide application timings were compared, from maize flowering to approximately 15 days after the flight peak of the adult. At harvest, the ears were rated for incidence and severity of ECB damage, fungal ear rot symptoms and fumonisin (FB1 + FB2) contamination. In all the years/sites, the treatments applied at the beginning of a consistent ECB flight activity showed the best efficacy to control the insect damage on ears. Fungal ear rot and fumonisin contamination were significantly affected by ECB control. The efficacy of the best timing of insecticide application to control fumonisin contamination was on average 93%, compared to the untreated control. Contamination levels of these mycotoxins increased moving to either an earlier or later treatment; furthermore an earlier insecticide application showed lower fumonisin contamination than a treatment applied after the adult flight peak. The production of maize kernels and maize-based foods that do not exceed the maximum international and EU permitted levels for fumonisins could be enhanced by an appropriate insecticide treatment against the second generation ECB. The optimum insecticide application timing is comprised between the beginning of the consistent adult flight activity and the flight peak