The effects of silicon accumulation in corn on the fall armyworm (Lepidoptera: Noctuidae)

Hiltpold, IvanThe fall armyworm [FAW, Spodoptera frugiperda (Smith)] is a major economic pest in the United States and has recently become a significant concern in Africa and Asia. With its acquired resistance to many current control strategies, like pesticide application and transgenic corn, alternative management techniques are becoming a necessity. The use of silicon (Si) as a pest control agent has shown promise in many systems in the past with a variety of plant species due to its ability to alter plant defense responses and mechanically damage herbivorous insects. In this study FAW was used as a model pest species to understand how its growth and ability to survive infection by a parasite are affected when feeding on Si supplemented corn plants. Corn (Zea mays L.) was found to accumulate Si, however, this ability varied between cultivars. Feeding damage from FAW larvae caused the release of volatile organic compounds, but Si did not have a significant effect on these. Feeding on Si supplemented plant material did not have a negative effect on the growth or consumption rate of FAW larvae. A significant reduction in live mass was seen only in FAW pupae that had been fed with Si supplemented plant material. FAW larvae had high mortality rates when exposed to the entomopathogenic nematode Heterorhabditis indica Poinar, Karunakar, & David. Larvae that consumed a high Si diet had a significantly lower mortality rate than larvae that consumed untreated corn. FAW moths had a greater preference for undamaged plants for oviposition than FAW infested plants. Si had little to no effect on the oviposition preferences of FAW moths. These findings do not support the use of Si as a method of controlling FAW on corn.University of Delaware, Department of Entomology and Wildlife EcologyM.S