Predatory potential of geocoris spp. and orius insidiosus on fall armyworm in resistant and susceptible turf

Abstract

Predatory potential and performance of the predaceous heteropterans, Geocoris punctipes (Say), G. uliginosus (Say) (Geocoridae), and Orius insidiosus (Say) (Anthocoridae), were evaluated using fall armyworm, Spodoptera frugiperda (J. E. Smith), as prey on different turfgrass taxa (resistant zoysiagrasses, 'Cavalier' and 'Palisades'; moderately resistant Bermuda grass, 'TifSport'; and susceptible seashore paspalum, 'Sea Isle 1') through laboratory and field studies. When background mortality was taken into account, in small arena trials in the laboratory, the greatest mortality by predators occurred on TifSport. The predator impact on TifSport by O. insidiosus was 92.6% above the mortality in the no-predator treatment on that grass. Predator induced mortality was rarely significant on the highly resistant zoysiagrass cultivar Cavalier because mortality, even in the absence of predators, was so high. Survival of larvae on TifSport Bermuda grass was significantly reduced by the addition of just two O. insidiosus per pot in laboratory pot trials. An increase in predator density to 4, 6, 8, or 10 further suppressed larval survival. O. insidiosus reduced larval survival on Sea Isle 1 at all densities. On Sea Isle 1, a density of two O. insidiosus resulted in >50% reduction in live fall armyworms compared with the no predator treatment in laboratory trials. However, addition of O. insidiosus did not significantly reduce survival of fall armyworm larvae on this cultivar in the field in the presence of alternative prey and predators. O. insidiosus densities of six or higher per 181.4 cm 2 did significantly reduce larval survival on TifSport Bermuda grass by as much as 80% during a 5-d trial period in the field. Predator-induced mortality among all trials was most consistent on a grass of intermediate resistance, TifSport Bermuda grass. © 2009 Entomological Society of America.