Incidence of mycotoxins in Bt and conventional corn hybrids in relation to insect pest abundance

Mycotoxins are fungal metabolites that can contaminate foods and feeds causing toxic effects in higher organisms that consume these products. The more common mycotoxins in corn are fumonisin, aflatoxin and deoxynivalenol (DON), and they are known to cause health issues in humans and animals (Hussein, 2001). Dry weather early in the season followed by wet weather during silking stage combined with insect damage on corn ears may increase the amount of fungal infection (Munkvold, 1999). Conventional and Bt corn plots were located in Aurora, South Dakota during 2009 year. Carbaryl was applied at 1.12 Kg[AI]/ha in half the plots to eliminate beneficial arthropods and thus trigger later-season pest resurgence contaminants. Sap beetles in the sprayed Bt plots were 50-fold greater in numbers than that observed in untreated-Bt plots. Corn rootworms were over 3-fold greater in conventional corn plots compared to that found in Bt treatments. Corn leaf aphid numbers were highest in sprayed-Bt plots compared to all treatments. Mycotoxins levels showed no significant differences between hybrids and insecticide treatments. Zearalenone was the only mycotoxin that showed significant differences comparing with fumonisin, aflotoxin and deoxynivalenol (DON) in both hybrids. Zearalenone, aflotoxin, fumonisin nor DON levels were not significantly correlated with the percent of ears with visibly moldy insect-damaged kernels. Based on the levels of mycotoxins results conventional and Bt corn hybrids did not exceed the tolerated mycotoxin levels of human and animal consumption.