Submitted to: American Society of Sugar Cane Technologists
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/31/2008
Publication Date: 11/14/2008
Citation: Reagan, T.E., Akbar, W., Showler, A. 2008. Free amino acids - determinant of sugarcane resistance/susceptibility to stalk borer and sap feeders. American Society of Sugar Cane Technologists. 28:44-45. Interpretive Summary: Two key pest species of Louisiana sugarcane, the Mexican rice borer and the sugarcane aphid, are assessed for their preference and performance on different sugarcane varieties. Free amino acids in the host plant were analyzed and associated with observed oviposition preference, reproductive rate, and performance of the two pests on the varieties. We found that preferences and performance of each pest species was associated with free amino acids that are essential to insect growth and development, and this may be used to characterize observed cultivar resistance.
Technical Abstract: Two relatively new key species in Louisiana that conform to the plant stress hypothesis are the Mexican rice borer, Eoreuma loftini (Dyar) and the sugarcane aphid, Melanaphis sacchari (Zehntner). High performance liquid chromatography differentiated insect resistant and susceptible sugarcane cultivars based on nutritional profiles involving free amino acids (FAAs). For E. loftini susceptible cultivar LCP 85-384, concentrations of essential and nonessential FAAs in whole leaf tissue samples were more than twice as high as in the resistant cultivar HoCP 85-845. Similarly, M. sacchari susceptible L 97-128 exhibited more than three fold higher concentrations of essential FAAs in the phloem sap compared to the resistant cultivar, HoCP 91-555. Two essential FAAs, histidine and arginine, were detected only in the sap of L 97-128. A novel approach to evaluate insect resistant and susceptible cultivars is proposed.