New Source of Southern Chinch Bug (Hemiptera: Lygaeidae) Resistance in a Diploid Selection of St. Augustinegrass

Abstract

Over 400,000 ha of St. Augustinegrass, Stenotaphrum secundatum (Walt.) Kuntze, are managed as a turfgrass in the southern United States, and the southern chinch bug, Blissus insularis Barber, is its most important insect pest. New sources of host plant resistance to southern chinch bugs became necessary due to the development of virulent populations of chinch bugs which were able to feed on the only acceptable resistant cultivar, Floratam. Initial testing evaluated 14 lines for chinch bug resistance using insects collected from five locations from Palm Beach Co., FL. Host plant resistance was determined by mortality of adult chinch bugs held on a turfgrass for 14 d. A second study was conducted with five lines from the first test with southern chinch bugs collected from nine locations throughout Florida. Tests showed a high level of southern chinch bug resistance in NUF 76, NUF 216 and FX-10. Leaf blades of NUF-76 are significantly shorter and narrower than other tested St. Augustinegrass lines when evaluated 2 wks after mowing. NUF-76 is unique because for the first time, resistance to the southern chinch bug has been identified within a diploid line of St. Augustinegrass. Prior to this, southern chinch bug resistance was only associated with polyploid lines which generally have large leaves and reduced or no seed set due to sterility problems. This discovery will allow chinch bug resistance to be more easily bred into other St. Augustinegrass lines.

Interploid St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] hybrids recovered by embryo rescue

“…The most notable of the recovered progeny had African polyploid genotypes as maternal parents. For example, FX-10 is a cultivar derived from African polyploid germplasm known to possess genes conferring the most stable form of resistance to chinch bug (Busey 2003;Nagata and Cherry 2003). Future breeding efforts should focus on crossing these exotic genetic resources with superior diploid cultivars to improve sod production, cold hardiness, color, texture, shade tolerance, and marketable turf quality in St. Augustinegrass.…”

“…Floratam was the industry standard for chinch bug resistance until being rendered obsolete by the polyploid-damaging population (PDP) biotype of the pest (Busey 2003). With the identification of a diploid cultivar (NUF-76 also known as 'Captiva') possessing resistance to the PDP chinch bug (Nagata and Cherry 2003), it is technically feasible to stack resistance genes by crossing Floratam or FX-10 with NUF-76. Turf quality characteristics of NUF-76, however, are unknown and warrant evaluation.…”

“…For St. Augustinegrass, it was initially thought that only polyploids were resistant (Reinert et al 1986). One exception is the recent identification of a diploid with resistance to the southern chinch bug biotype that overcame the resistance in Floratam (Nagata and Cherry 2003). Various genetic resistances among the polyploids include (as has already been indicated) resistance to some biotypes of southern chinch bug (Reinert and Dudeck 1974); resistance to the SAD virus (Horn et al 1973); and resistance genes to the sting nematode, Belonolaimus longicaudatus Pace (Busey et al 1993).…”

Oxidative Responses of St. Augustinegrasses to Feeding of Southern Chinch Bug, Blissus insularis Barber

“…Floratam, a polyploid variety of St. Augustinegrass with resistance to southern chinch bug, was released in Florida and other Gulf Coast states in 1973 (Horn et al 1973). However, in 1985, a population of chinch bug in Florida was reported to have overcome Floratam's resistance (Busey and Center 1987); this ability to use Floratam as a host is now widespread throughout Florida (Nagata and Cherry 2003).…”

“…As potential alternatives to Floratam, two southern chinch bug resistant St. Augustinegrass varieties were developed: a polyploid line, FX-10 (Busey 1993) and a diploid line, Captiva (Nagata and Cherry 2003). We have shown that both FX-10 and Captiva deter feeding of southern chinch bugs (i.e., through antixenosis) (Rangasamy et al 2006).…”