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POSTERS: Pathogen-vector/insect interactions

What happens in storage: Mold-moth interactions on conventional and transgenic maize hybrids
Julie Aiza Mandap - University of the Philippines Los Banos / Iowa State University. Derrick Mayfield- Iowa State University, Gary Munkvold- Iowa State University, Richard Hellmich- USDA ARS, Mark Busman- USDA ARS

Grain quality of maize after harvest is reduced primarily by mold and insect infestations. When stored under high temperature and moisture conditions, Aspergillus flavus contamination, associated with aflatoxin production, has been known to considerably increase in levels. Indianmeal moth (IMM) or Plodia interpunctella, a Lepidopteran stored-grain pest, directly feeds on kernels thereby potentially predisposes grain to infection and mycotoxin contamination. Insect-mold interactions have been studied thoroughly in the field but not in storage, particularly the effect of Lepidopteran events on IMM. In this study, Bt and non-Bt maize hybrids at 16-17% moisture content, were artificially inoculated with A. flavus and kept at 32oC and 80-85% relative humidity in continuous dark to simulate storage conditions. IMM was allowed to feed and complete one-generation cycle for 28 days. Survival of IMM on transgenic grain expressing Bt proteins Cry1Ab, vip3Aa20, and Cry1Fa2 solely or in combination were none or lower compared to the non-Bt grain. Feeding damage incurred by IMM was contingent on the suitability of grain for IMM development. Deterred feeding of IMM resulted in the reduction of A. flavus and aflatoxin levels. The use of transgenic hybrids with genes for Lepidopteran resistance hinders IMM feeding and mitigates the risk of mold and mycotoxin contamination. This is particularly valuable especially in areas where keeping maize at low moisture levels during storage remains a challenge.