Fall armyworm performance on commercial turfgrass cultivars and insecticide susceptibility

Fall armyworm (FAW) is an economic pest in turfgrass systems. Few studies have documented the impact of combining the IPM tactics of host plant resistance and insecticides to manage FAW. The study aims to determine the insecticide susceptibility of FAW rice-strain feeding on turfgrass cultivars with and without known antibiosis resistance to FAW. The study was performed at the UF/IFAS West Florida Research and Education Center in a completely randomized design with 30 replications and FAW rice strain from a field-derived population. Larvae of FAW were fed on zoysiagrass, bermudagrass, and St. Augustinegrass cultivars until reaching the second/third instar and submitted to concentration-response bioassays of three insecticides (bifenthrin, indoxacarb, and chlorantraniliprole) commonly adopted in turfgrass against FAW. Five concentrations of each insecticide were individually prepared in addition to a water control. Stolons of the cultivars of zoysiagrass (‘Zeon’), bermudagrass (‘Celebration’), and St. Augustinegrass (‘Floratam’) were dipped into the solution. Once the excess solution on the stolon dried, it was placed into plastic cups containing agar substrate. One FAW larva was transferred to each plastic cup, and the mortality of each concentration was recorded after 48h (bifenthrin and indoxacarb) or 72h (chlorantraniliprole). The insecticide susceptibility of FAW fed on different turfgrass cultivars was contrasted. The impact of the results of insect resistance management programs in turfgrass systems will be discussed.