Relationship between corn earworm feeding and corn ear fungi contamination

Corn earworm is a widespread agricultural pest in the southern United States, and its feeding on corn ears may influence the growth of ear-rotting fungi by facilitating ear access for infection. Strains of fungi, such as Aspergillus flavus and Fusarium verticillioides can produce mycotoxins harmful to human and animal health, causing a range of problems from respiratory distress to death. Tests were conducted to investigate the relationship between earworm feeding damage on the presence of fungi quantity, type, and mycotoxin concentration in field corn. Corn hybrids with no Bt proteins (non-Bt), Cry1A.105 + Cry2Ab2 (VT2P), and Cry1A.105 + Cry2Ab2 + Vip3Aa (Trecepta) were either sprayed twice weekly with Beseige insecticide directly upon individual ears from silk extrusion to brown silk to reduce corn earworm infestations or left untreated. Corn earworm ear feeding damage and fungi growth were assessed at harvest. Regardless of corn Bt technology or spray regime, fungi contamination was greatest where corn earworm damage was most severe. Fungi identified included Penicillium sp., Aspergillus niger., Aspergillus flavus, and Fusarium verticillioides. There was a significant positive correlation between earworm feeding and amount of ear-rot fungi present for all corn hybrids except Trecepta. While the majority of the fungi samples taken were atoxigenic and do not pose a health threat, their presence still affects corn yield and atoxigenic strains have the potential to be surrogates for toxigenic strains.