Tolerance in St. Augustinegrass Germplasm Against Blissus Insularis, Barber (Hemiptera:Blissidae)

St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] is a widely used lawn grass in the southern United States due to its stoloniferous growth habit and shade tolerance. However, St. Augustinegrass is prone to thatch accumulation, which is conducive to pest problems, with the southern chinch bug (Blissus insularis Barber, SCB) being the most economically important one. Previous work to identify additional sources of SCB resistance reported genotypes with comparatively high numbers of recovered insects but low damage ratings. This study was conducted (i) to evaluate the performance of these materials in response to varying SCB feeding densities, and (ii) to determine feeding and oviposition under no-choice scenarios. Genotypes exposed to 0, 10, or 30 adult SCBs were evaluated after 4 wk for damage and insect survival. Significant differences were observed among genotypes. Across infestation levels, while recovered insect numbers for susceptible check ‘Seville’ and plant introductions 509038 and 509039 were not significantly different, damage ratings were significantly lower for the latter, indicating that these materials were tolerant to SCB feeding. In the no-choice experiments, survival levels of both males and females on week 4 were significantly lower for resistant check ‘FX10’, PI 365031, and PI 289729. These genotypes, along with PIs 291594, 300129, and 647924, showed significantly lower SCB oviposition and feeding compared with Seville. Our study was able to confirm that two PIs display tolerance to SCB feeding, and five additional PIs have antibiosis activity against adult SCB (likely antibiosis), representing sources of SCB resistance for future St. Augustinegrass breeding efforts.