Evaluation of cool- and warm-season grasses for resistance to multiple chinch bug (Hemiptera: Blissidae) species.

Chinch bugs are common pests of many agronomic and horticulturally important crops and turfgrasses. The extensive overlap of plant hosts and geographic distribution of Blissus leucopterus leucopterus (Say), Blissus leucopterus hirtus Montandon, Blissus insularis Barber, and Blissus occiduus Barber underscores the importance of identifying resistant germplasm. Cool- and warm-season turfgrasses and sorghum, Sorghum bicolor (L.) Moench, were evaluated for resistance to chinch bugs in the Blissus complex, and the presence of multiple resistance was documented. Greenhouse studies established that B. occiduus-resistant ('Prestige', formerly NE91-118) and -susceptible ('378') buffalograsses,, Buchloë dactyloides (Nuttall) Engelmann, were susceptible to all other chinch bug species. KS94 sorghum exhibited resistance to both B. occiduus and B. l. leucopterus, whereas B. insularis-resistant St. Augustinegrass, Stenotaphrum secundatum (Walter) Kuntze ('Floratam'), was also resistant to B. occiduus. B. l. leucopterus-susceptible sorghum ('Wheatland') and B. insularis-susceptible St. Augustinegrasses ('Raleigh' and 'Amerishade') were highly resistant to B. occiduus. Endophyte-free and -enhanced fine fescues (Festuca spp.) were moderately to highly susceptible to B. l. hirtus but moderately to highly resistant to B. occiduus. The results of this research showed the buffalograsses evaluated, including B. occiduus-resistant Prestige, are moderately to highly susceptible to the three other chinch bug species. In contrast, B. occiduus did not cause considerable damage to any of the turfgrasses or sorghum cultivars evaluated, other than buffalograss, irrespective of whether or not they are resistant to another chinch bug species. This information is increasingly important as various grasses become adapted to regions that may possess chinch bug species other than those with which they are typically associated. These levels of Blissus resistance should be included when selecting resistant germplasm for managing Blissus species pests.

Chinch bug (Hemiptera: Blissidae) mouthpart morphology, probing frequencies, and locations on resistant and susceptible germplasm.

Chinch bugs are common pests of many agronomic and horticulturally important crops and turfgrasses. Previous research has indicated that some grasses exhibit resistance to multiple chinch bug species, whereas others are resistant to only one species. The objectives of this research were to document differences in the probing frequencies and locations among Blissus species as well as differences in mouthpart morphology as a first step in understanding the differential responses of grasses to chinch bug feeding. Scanning electron microscopy detected differences in the total lengths of proboscises as well as individual mouthpart segments among the four species studied. Blissus occiduus Barber probed significantly more often on buffalograss, Buchloë dactyloides (Nuttall) Engelmann, than any other plant material. Probing locations of B. occiduus and Blissus leucopterus leucopterus (Say) were similar on both B. occiduus-resistant and susceptible buffalograsses and KS94 sorghum, Sorghum bicolor (L.) Moench (B. occiduus-resistant, B. l. leucopterus-resistant). However, on 'Wheatland' sorghum (B. occiduus-resistant, B. l. leucopterus-susceptible), stylet tracts of B. l. leucopterus most often terminated in the bundle sheath cells, whereas those of B. occiduus generally terminated in the vascular tissues.