Buffalograss resistance to the chinch bug, Blissus occiduus: An investigation of tolerance and antixenosis.

摘要

In recent years, buffalograss, Buchloe dactyloides (Nuttall) Engelmann, has received considerable attention as an alternative turfgrass species because of its low maintenance requirements and excellent drought tolerance. Although few arthropods are injurious to buffalograss, the chinch bug, Blissus occiduus Barber, has emerged as an important insect pest of this warm-season grass. In my research I evaluated selected buffalograss germplasm for resistance to B. occiduus and explored antixenotic and tolerance mechanisms of chinch bug-resistant buffalograsses.; Based on turfgrass damage, NE91-118, 'Tatanka', 'Bonnie Brae', and 'Cody' were highly to moderately resistant. These four buffalograsses exhibited minimal chinch bug damage, although all were heavily infested with chinch bugs. NE84-45-3 and '378' were highly susceptible to B. occiduus.; The relative levels of tolerance, antibiosis, and antixenosis among the resistant buffalograsses (NE91-118, Cody, and Tatanka) were determined by choice and no-choice studies. From the no-choice studies, NE91-118, Cody, and Tatanka were characterized as tolerant to B. occiduus. Antibiosis studies found no significant differences in chinch bug fecundity, nymphal development, and chinch bug survival among the resistant and susceptible buffalograsses. Choice studies indicated the presence of antixenosis in NE91-118, whereas Cody and Tatanka showed little or no antixenosis.; Another component of this research investigated physiological and biochemical mechanisms underlying buffalograss tolerance to chinch bug feeding. Studies investigating physiological differences between chinch bug susceptible and tolerant plants by measuring rates of photosynthesis demonstrated photosynthetic compensation in the tolerant buffalograss, NE91-118. Enzyme activity assays and protein profiles showed that chinch bug feeding leads to a loss in catalase activity in susceptible buffalograsses. Resistant buffalograsses, on the other hand, may be able to tolerate chinch bug feeding by increasing their peroxidase activity.; Development of chinch bug-resistant buffalograsses offers the most effective, economical, and environmentally-responsible approach for managing chinch bug populations affecting buffalograss. Results of this research provide essential information for developing improved turf-type buffalograsses with enhanced chinch bug resistance and for investigating the mechanisms of chinch bug-resistance in buffalograss.