Categories of Resistance in St. Augustinegrass Lines to Southern Chinch Bug (Hemiptera: Blissidae)

Abstract

The southern chinch bug, Blissus insularis Barber (Hemiptera: Blissidae), is the most important insect pest of St. Augustinegrass, Stenotaphrum secundatum (Walt.) Kuntze, in Florida and other Gulf Coast states. Resistance to southern chinch bug was identified previously in St. Augustinegrass lines 'FX-10' and NUF-76. Choice and no-choice tests and ovipositional and developmental studies were conducted to determine the categories of resistance in FX-10 and NUF-76 to southern chinch bug. When adult chinch bugs had a choice among attached stolons of three susceptible lines ('Floratam', 'Bitter Blue', and 'Palmetto') and the two resistant lines, chinch bugs were found significantly more often over a 5-d period on the susceptible lines. This result indicates the presence of antixenosis in the resistant lines FX-10 and NUF-76. In a no-choice study, chinch bugs produced less than half as many excretory spots on FX-10 as on the susceptible lines. Significantly fewer excretory spots produced by chinch bugs confined on NUF-76 accumulated by days 3 and 5 after release; however, on the first 2 d, the accumulative number of excretory spots was not significantly less than that found on susceptible lines. The no-choice study confirmed a high level of antixenosis in FX-10, a moderate level of antixenosis in NUF-76, and possible antibiosis in NUF-76. Ovipositional and developmental studies were conducted using only Floratam (a widely planted cultivar that was formerly resistant to B. insularis) and the two resistant lines. Adults released on Floratam produced 11 and 5 times more eggs and 18 and 9 times more offspring than adults on FX-10 and NUF-76, respectively. Plant anatomical and biochemical studies are required to investigate the exact cause of antixenosis in FX-10 and NUF-76 and possible antibiosis in NUF-76.

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

“…The fact that enzyme induction differs between the two resistant cultivars suggests that the mechanisms of resistance also differ. This corroborates our finding (Rangasamy et al 2006) that while FX-10 shows antixenosis to southern chinch bug, Captiva exhibits both antixenosis and antibiosis. Together, our results support the hypothesis that oxidative enzymes play a vital role in herbivore resistance in plants.…”

“…Lipid peroxidation end products could be deterrent to insect feeding and operate via antixenosis, or be toxic and function via antibiosis (Felton et al 1994a). Both modalities of resistance occur in St. Augustinegrass against the southern chinch bug (Rangasamy et al 2006). Shukle and Murdock (1983) demonstrated that LOX could act directly as a defense against insect attack in soybean.…”

“…We have shown that both FX-10 and Captiva deter feeding of southern chinch bugs (i.e., through antixenosis) (Rangasamy et al 2006). Captiva also had adverse effects on the biology of the southern chinch bug (i.e., antibiosis) (Rangasamy et al 2006), suggesting a metabolic basis for insect resistance.…”

Role of Leaf Sheath Lignification and Anatomy in Resistance Against Southern Chinch Bug (Hemiptera: Blissidae) in St. Augustinegrass

“…Plant material was supplied by R. Nagata (Everglades Research and Education Center, Belle Glade, FL). The plants were grown as described by Rangasamy et al (2006). In brief, rooted sprigs from single node cuttings were grown in plastic pots (12.5 cm in diameter by 12.5 cm in depth) containing a potting medium of 1:1 (vol:vol) sand and Fafard mix #2 (Conrad Fafard, Agawam, MA).…”

“…Both FX-10 and Captiva have high levels of antixenosis to southern chinch bug and Captiva may exhibit antibiosis (Rangasamy et al 2006). Electrical penetration graph (EPG) studies revealed that southern chinch bugs took longer to begin ingestion and spent less time ingesting on FX-10 and Captiva compared with their susceptible controls Floratam and ÔPalmettoÕ (Rangasamy 2008).…”