SPECIAL SESSION: Mycotoxin Mayhem: Insect Pests In The Mix
Influence of insects on fumonisin contamination of maize grain by Fusarium and Aspergillus species
Gary Munkvold - Iowa State University. Derrick Mayfield- Iowa State University
Fumonisins and other mycotoxins can accumulate in maize grain and reduce grain quality and value, due to the effects of these compounds on the health of livestock and humans. Fumonisins are primarily produced by Fusarium verticillioides and other species in the F. fujikuroi complex, but they also can be produced by Aspergillus species in section Nigri. Most fumonisin-producing fungi are not aggressive pathogens of maize ears, but they readily colonize damaged kernels, especially those damaged by insect feeding. Insects in several orders including Lepidoptera, Coleoptera, and Thysanoptera have been implicated as vectors and/or as damaging agents leading to mycotoxin contamination of maize. Widespread use of maize hybrids with transgenic resistance to insects has significantly altered the epidemiology of fumonisin-producing fungi by reducing insect damage to kernels and suppressing populations of the European corn borer. However, insects continue to play an important role in grain contamination by fumonisins and other mycotoxins, due to the limited spectrum of activity of insect-resistance genes, and reduced sensitivity of target insects in some environments. Other fungi that do not produce fumonisins also interact with insects; in some cases these fungi have been shown to compete with fumonisin-producing species, reducing fumonisin contamination but causing grain contamination by other mycotoxins. Insect management continues to be a key component in strategies to reduce the risk of mycotoxin contamination of maize.