Comparative activity of agrochemical treatments on mycotoxin levels with regard to corn borers and Fusarium mycoflora in maize (Zea mays L.) fields

Field trials were carried out in nine areas located in France during 2004, 2005 and 2006 to study the control of Lepidoptera caterpillars by agrochemical treatments and their consequences on Fusarium spp. mycoflora and mycotoxin levels. Treatments involved either an insecticide or an insecticide–fungicide association. Two species of maize borers: Ostrinia nubilalis Hübner [Lepidoptera: Crambidae] and Sesamia nonagrioides Lefebvre [Lepidoptera: Noctuidae], were monitored. Although the insect populations were controlled by agrochemicals, there was no reduction in Fusarium spp. mycoflora. Conversely a significant reduction of mycotoxin (trichothecenes, fumonisins and zearalenone) levels resulted from insecticide treatment. These experiments and results are discussed regarding the biology of maize borers and relationships with Fusarium spp.