Physiological responses of resistant and susceptible buffalograsses to Blissus occiduus (Hemiptera: Blissidae) feeding.

The impact of Blissus occiduus Barber feeding on resistant ('Prestige') and susceptible ('378') buffalograsses, Buchloë dactyloides (Nuttall) Engelmann, was evaluated through measurement of carbon exchange rate, light and carbon assimilation (A-C(i)) curves, chlorophyll a fluorescence, and nonstructural carbohydrates. No significant differences in carbon exchange rates were observed between infested and control plants for 378 at 5 and 10 d after infestation; however, at 20 d after chinch bug introduction, significant differences in carbon exchange rates between infested and control 378 plants were detected. Carbon exchange rates were similar between infested and control Prestige plants at 5,10, and 20 d after infestation, suggesting that resistant plants can allocate energy for recovery from chinch bug injury. Significant differences in the photochemical efficiency of photosystem II (PSII) and the apparent photosynthetic electron transport ratio were observed between infested and control 378 plants, whereas, no significant differences in the photochemical efficiency of PSII and the electron transport ratio were detected between control and infested Prestige plants. Blissus occiduus-infested 378 and Prestige plants consistently had similar or higher levels of nonstructural carbohydrates compared with their respective control plants. These data suggest that both resistant and susceptible buffalograsses increase levels of nonstructural carbohydrates in response to B. occiduus feeding. This research also suggests compensatory photosynthesis takes place in Prestige but not in 378.