Abstract

Three species of Scapteriscus mole crickets were introduced to the southeastern United States around 1900 and have become major pests of turfgrasses, especially bermudagrass, Cynodon spp. The objective of this study was to evaluate genetic resistance among vegetatively propogated Cynodon genotypes to damage by tawny mole cricket, S. vicinus Scudder (Orthoptera: Gryllotalpidae). Genotypes of bermudagrass, including commercial cultivars, were evaluated for their response to the tawy mole cricket, in field screen cages. Adult tawny mole crickets were introduced into replicated cages in which bermudagrass plants were planted. Cage sidewalls extended 75 cm below the soil line to prevent migration. Damage estimates were based on visual ratings and relative reduction in clippings mass of harvested plants of paired Cynodon genotypes. The four cage pairs, mole-cricket-infested and noninfested, thus represented the main plots of a split-plot experiment in four replications. Differences were observed (P < 0.05) in tawny mole cricket damage among 26 genotypes evaluated across two experiments. `Tifdwarf', `Tifgreen', `Sunturf', `Texturf' and `Texturf-1-F' were the most susceptible and sustained more tunneling and feeding damage than any of the other genotypes. All bermudagrass selections tested were damaged, but `Ormond', FL-2400, PI-290659 and PI-291586 showed the least overall damage. Resistance scores (83 to 99) were high for each of these genotypes. `Tifway' and `FLora TeX', were common to both experiments, and each received similar intermediate damage and growth reduction rating. Tifgreen and Sunturf, were also common to both experiments but produced conflicting results. These differences among experiments may have been due to differing preferences exhibited among the different sets of cultivars, a higher infestation rate in one experiment and the corresponding higher feeding pressure by the resulting larger population of nymphs. The field screen cages provided an excellent environment to evaluate plant materials against a highly mobile soil insect such as the tawny mole cricket.