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Mycotoxin analysis of Bt and non-Bt maize from ears inoculated with Fusarium subglutinans and F. temperatum and infested with lepidopteran insects.

Derrick Mayfield: Iowa State University

<div>Prior to 2011, <em>Fusarium temperatum</em> (Ft) was referred to as <em>F. subglutinans</em> Group I and the role of Ft in Fusarium ear rot and mycotoxin contamination in North America has not been established. In 2015 and 2016, field experiments were conducted in Iowa with Fs or Ft silk channel inoculations and with corn earworm (<em>Helicoverpa zea</em>) or European corn borer (<em>Ostrinia nubilalis</em>) infestations on Bt and non-Bt maize. Ear rot severity and insect injury were estimated visually and a multi-mycotoxin analysis was performed on milled grain. In both years, Fusarium ear rot severity and insect injury was lower in the Bt hybrid, and Ft inoculation resulted in higher levels of moniliformin compared to Fs (<em>P</em><0.0001). In 2016, <em>H. zeae</em> infestation increased ear rot severity (<em>P</em>=0.0452) compared to the non-infested control and both insects caused increased moniliformin levels in Ft-inoculated treatments (<em>P</em><u><</u>0.0055). In 2015, grain from Fs-inoculated treatments had higher levels of fusaric acid than Ft treatments (<em>P</em><0.0001). In 2016, Fs-inoculated treatments had the highest levels of fusaproliferin which were increased by insect infestations, whereas Ft-inoculated treatments had the highest levels of beauvericin, also increased by insect infestations (<em>P</em><0.0001). There were large differences between Ft strains regarding moniliformin, fusaproliferin, beauvericin, and gibberellic acid levels. The highest levels of fumonisins in 2015 were detected in non-inoculated, non-Bt, insect-infested treatments. However in 2016, insect infested, non-inoculated treatments of both hybrids had the highest fumonisin levels (<em>P</em><u><</u>0.0001).</div>