Potential of Silicon to Improve Biological Control of Fall Armyworm, Spodoptera frugiperda on Maize
Kennedy J. Zimba, Quentin D. Read, Muhammad Haseeb, Robert L. Meagher, Jesusa C. Legaspi
Abstract
Silicon (Si) accumulation in plants confers a mechanical barrier to insect herbivory and may alter plant chemistry to increase the attraction of natural enemies to host insect herbivores on Si−treated plants. The fall armyworm (FAW), Spodoptera frugiperda, is a major insect pest of grain crops, including maize (Zea mays L.). This study examined whether Si supplementation alters maize volatile compounds that mediate host location in Euthyrhynchus floridanus, a generalist predator of FAW. A four-arm olfactometer was used to test the olfactory preference of nymphs and adults of E. floridanus to the odor of maize leaf materials from plants that were; Si−treated and infested, Si−treated without infestation, Si−deprived and infested, and Si−deprived without infestation. The probabilities of individual insects choosing between the four treatments were estimated using a multinomial generalized linear mixed model. There were no statistical differences in the olfactory preference of E. floridanus between Si−treated and Si−deprived maize leaf materials. However, the median estimate showed that nymphs were almost twice likely to be attracted to Si−supplemented leaf material, indicating a potential positive effect of Si. However, a more robust follow-up study is needed to further assess the impact of Si on E. floridanus.