St. Augustinegrass
How are the Southern Chinch Bugs doing in Texas?
Dr. James A. Reinert
Professor of Entomology &
TAES Regents Professor
Texas A&M University Res. & Ext. Center
Dallas, TX 75252-6599
J-Reinert@tamu.edu
The Southern Chinch Bug, Blissus insularis Barber, is the most destructive pest of St. Augustinegrass throughout its area of adaptation from coast to coast across the southern USA and it is a pest where ever the grass is grown from Bermuda to Hawaii. In many residential and commercial landscapes, it is the single limiting stress to St. Augustinegrass turf and has been responsible for a loss-of-stand and a need to re-establish the turf with new sod.
St. Augustinegrass is the preferred host, although this chinch bug will also feed on several other grasses including bermudagrass. As the bugs feed, they suck the plant juices and inject a toxin into the plant which causes the grass to turn yellowish and then brown and die. If left uncontrolled, an entire lawn will be destroyed.
In 1973, Floratam St. Augustinegrass was developed jointly by the Texas Agricultural Experiment Station and the Florida Agricultural Experiment Station (Horn et al. 1973). At that time, I identified outstanding resistance to the Southern Chinch Bug in ‘Floratam’ (Reinert and Dudeck 1974; Reinert 1978). In fact, this new grass actually killed from 80% to >90% of the bugs that were confined on the stolons within only 7 days. Floratam exhibited a high level of antibiosis (the host kills the pests). As a result, Floratam was widely planted throughout the Southeast and across to Texas. It was also resistant to the St. Augustinegrass virus (SAD) (Reinert, et al. 1980) but its weakness was its sensitivity to cold temperatures in the northern parts of Texas.
The resistance lasted until 1985 when populations of Southern Chinch Bug in central and southern Florida were reported killing stands of Floratam in both sod production and in landscapes. Laboratory studies confirmed that the resistance in Floratam had been compromised after a successful ‘field life’ of ca. 12 years (Busey and Center 1987). In lab studies, nymphs of this new biotype were able to survive for 62 days, produce abundant eggs and were able to develop to adults when confined on Floratam stolons. The breakdown of Floratam resistance was confirmed by Cherry and Nagata (1997). Reinert et al. (2004) provided an in-depth review of host resistance in St. Augustinegrass to the Southern Chinch Bugs. The resistance in Floratam still serves as an excellent example of host resistance, since insect resistance in other crops such as wheat, corn and sorghum often only lasts for about half that long.
Since the breakdown of the Floratam resistance, researchers in Florida and more recently the St Augustinegrass Breeding Program at Texas A&M-Dallas has been searching for a good replacement grass with resistance to chinch bugs. ‘FX-10’ was developed and released in Florida by Busey (1993). This grass is highly resistant to chinch bugs in Florida and kill >90% of the bugs within 2-weeks. Also, a diploid breeding line, NUF-76, of St. Augustinegrass was identified with good resistance to the Floratam resistant biotype (Nagata and Cherry 2003). Floratam and the other resistant cultivars were all polyploid.
Recent Findings:
What we know about the Chinch Bugs in Texas
- Southern Chinch Bugs in Texas appear to be a new biotype of
virulent bugs (VTSCB-2005)
- Texas Southern Chinch Bugs have also overcome the resistance in Floratam
- Southern Chinch Bugs in Texas are not susceptible to the resistance in FX-10
Our recent studies show that a population of Southern Chinch Bugs from the Bay City –Wharton Area (the heart of the St. Augustinegrass production area of Texas) is not affected by the resistance in cultivars of either Floratam or FX-10. In at least two different experiments both of these cultivars only killed 20% or less of the confined adult chinch bugs within a 7-day feeding period in the laboratory. We are currently evaluating the new breeding line from Florida, NUF-76 which has shown high levels of antibiosis against the Florida strains of the Southern Chinch Bug.
How other new Cultivars of St. Augustinegrass
Respond to the new Virulent Texas (VTSCB-2005)
Cultivar % dead after 7 days
----------------------------------------
Delmar 16
Mercedes 16
Palmetto 20
Seville 16
Winchester 16
FX-10 16
Floratam 15
TX Common 10
None of the newer cultivars that I evaluated that have entered the market within recent years show any resistance to VTSCB-2005, the Texas strain.
The Future is Bright
In the St. Augustinegrass breeding program headed by Drs. M.C. Engelke and Dennis Genovese, we have several new breeding lines that are exhibiting greater than 65% kill of the confined (in no-choice studied) bugs in replicated laboratory studies. Two of the hybrids are providing 74 and 83% mortality of the chinch bugs.
The future looks good for a new cultivar with a high level of resistance to VTSCB-2005.
References Cited
Busey, P. 1993. Registration of FX-10 St. Augustinegrass. Crop Sci. 33: 214-215.
Busey, P. and Center, B.J. 1987. Southern chinch bug (Hemiptera: Heteroptera: Lygaeidae) overcomes resistance in St. Augustinegrass. J. Econ. Entomol. 80: 608-611.
Cherry, R.H. and R.T. Nagata. 1997. Ovipositional preference and survival of southern chinch bugs (Blissus insularis Barber) on different grasses. Int. Turfgrass Soc. Res. J. 8: 981-986.
Horn, G.C., Dudeck, A.E. and Toler, R.W. 1973. ‘Floratam’ St. Augustinegrass: A fast growing new variety for ornamental turf resistant to St. Augustine decline and chinch bug. Florida Agric. Exp. Stn. Circ. S-224. 13 p.
Nagata, R. and Cherry, R. 2003. New source of southern chinch bug (Hemiptera: Lygaeidae) resistance in a diploid selection of St. Augustinegrass. J. Entomol. Sci. 38: 654-659.
Reinert, J.A. 1978. Antibiosis to the southern chinch bug by St. Augustinegrass accessions. J. Econ. Entomol. 71: 21-24.
Reinert, J.A., Bruton, B.D. and Toler, R.W. 1980. Resistance of St. Augustinegrass to southern chinch bug and St. Augustine decline strain of Panicum mosaic virus. J. Econ. Entomol. 73: 602-604.
Reinert, J.A. and Dudeck, A.E. 1974. Southern chinch bug resistance in St. Augustinegrass. J. Econ. Entomol. 67: 275-277.
Reinert, J.A., M.C. Engelke and J.C. Read. 2004. Host resistance to insects and mites,
a review – A major IPM strategy in turfgrass culture. 1st Int. Soc. Hort. Sci. Conf.
Turfgrass Manage. Sci. Sports Fields. Athens, Greece. Acta Hort. 661: 463-486.