Sorghum

By John P. Roche, Ph.D. The fall armyworm (Spodoptera frugiperda) is native to the Americas, but in the past six years has become invasive to Africa, Asia, ...

On pigeon pea, most of the larvae had only reached the third instar stage, and on cotton most larvae had only reached the second instar stage. They suggest that many of the plant species that were previously listed as host plants are damaged by fall armyworm in its armyworm mode but do not serve as hosts through the insect’s whole life cycle and thus are not truly host plants. “It is important to examine the preference of moths and the behavior and performance of larvae using whole plants. Professional experience includes serving as a scientist and scientific writer at Indiana University, Boston College, and the University of Massachusetts Medical School, and as an editor-in-chief of science periodicals at Indiana University and Boston College. The majority of the crop damage in agriculture has been to maize and sorghum. Volp says, “Our findings—overwhelming oviposition preference for maize and superior larval performance on maize—align with the infestation patterns we are seeing in the field.” Importantly, Volp and colleagues saw feeding damage from fall armyworm on all of their maize and sorghum plants, but on only some of their peanut, pigeon pea, and cotton plants. Ninety-five percent of larvae on maize had reached the third instar stage by the fifth day, whereas only 22 percent of larvae on cotton had become third instars. More than half of the larvae on maize, sorghum, and peanut had reached the fourth instar. To investigate host preference in fall armyworms, the team performed experiments on egg laying, larval performance, and larval growth. Larval survivorship was highest on maize and lowest on cotton, and larval development up to five days was fastest on maize and slowest on cotton. Because the species causes large amounts of crop damage, knowledge of which plants are preferred by fall armyworms will be invaluable for control strategies.