Biotype development in turfgrass insects - southern chinch bug

Southern chinch bug [Blissus insularis Barber] populations in Texas have changed significantly from populations present in the Southeastern U.S. Populations in Florida overcame the resistance in 'Floratam' St. Augustinegrass [Stenotaphrum secundatum Waltz (Kuntze)] in 1987 after the grass had provided resistance for ~ 14 years of field life. Subsequent releases of 'FX-10' (1990) and 'Captiva' (2008) cultivars have provided high antibiosis of chinch bugs (80-100% mortalities of confined bugs) in Florida. Populations were discovered in south-central Texas in 2005 that expressed low antibiosis (less than 20% mortalities) after 7 days of confined feeding on Floratam. Additional sampled populations across the state show that Floratam and FX-10 killed 20% of confined bugs in 7 days while Captiva killed 19% in 7 days and only 27% in 14 days. Some Texas populations were extremely non-responsive to these "resistant" cultivars; i.e. Floratam (4%), FX-10 (2%), and Captiva (4%) mortality at 7 days and Floratam (42%), FX-10 (48%), and Captiva (8%) mortality after 14 days of confined feeding in no-choice tests. Other populations were highly variable; Floratam (80%), FX-10 (88%), and Captiva (54%) mortality after 7 days of confined feeding. I believe enough evidence has been developed to designate the very virulent populations in Texas that has overcome the resistance in Captiva as Biotype 2, with the populations that overcame the resistance in Floratam as Biotype 1 and the original strain of southern chinch bugs that could not survive on Floratam as the Wild Type. A total of 26 different populations have been samples ranging from Longview, Dallas, Waco, Austin, San Antonio, Corpus Christi, College Station, Bryan, Wharton, Bay City, Huntsville, Houston, and League City, TX.