ABSTRACT Among six turfgrass genotypes tested, the bigeyed bug, Geocoris uliginosus nymphs varied in ability to reduce fall armyworm, Spodoptera frugiperda, larvae. The six grasses tested (‘Sea Isle 1’ and 561-79 seashore paspalum, Paspalum vaginatum; ‘TifSport’ and ‘TifEagle’ bermudagrass, Cynodon dactylon x C. transvaalensis); and Cavalier and ‘Palisades’ zoysiagrass (Zoysia japonica and Z. matrella) represented a range in resistance to S. frugiperda. In the laboratory, the greatest reduction in S. frugiperda larvae by a low density of G. uliginosus occurred on the resistant Cavalier zoysiagrass. A seven-fold difference in larval weight between those feeding on susceptible versus resistant grasses suggested that on the resistant grass larvae remained for a longer period in a size range susceptible to predation. Results of laboratory studies were not directly translated to the field, where a diverse predatory arthropod community varied in composition depending on turfgrass genotype. In the field, the greatest reduction in S. frugiperda larvae by a low density of G. uliginosus occurred on Sea Isle 1 and 561-79 seashore paspalum grass. In the field predaceous Heteroptera were most abundant in paspalum grasses and bermudagrasses, while Carabidae, Staphylinidae and Araneae were more common in zoysiagrasses as measured by vacuum samples. Carabids from pitfall traps were more common in bermudagrasses, Araneae and Staphylinids were similar among grass taxa, and Cicindellidae were most common in paspalumgrasses and bermudagrasses. Predation was never significantly decreased on resistant turfgrass cultivars in any of the experiments described herein, indicating no negative tritrophic interactions.
Species 1: Heteroptera Geocoridae Geocoris uliginosus (big-eyed bug)
Species 2: Lepidoptera Noctuidae Spodoptera frugiperda (fall armyworm)
Keywords: host plant resistance, biological control
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