ADVANCEMENTS IN THE USE OF A LABORATORY BIOASSAY FOR BASIC HOST PLANT RESISTANCE STUDIES

Modifications were made in laboratory bioassays for resistance of plants to the fall armyworm, Spodoptera frugiperda (J. E. Smith). A bioassay using a 6-mm diameter X 2-cm section of a plastic soda straw filled with a diet mixture proved sufficient to bioassay differences between resistant centipedegrass and susceptible bermudagrass. Chemical solvents used to dissolve plant fractions may in themselves be toxic to test insects. Ethyl alcohol required ca. 5 h to evaporate, when incorporated into an insect diet, before it was nontoxic to the fall armyworm. The bioassay was readily adaptable for use in the search for antibiotic factors from exotic plant species.