Sugars and free amino acids in weed and crop host plants of the Mexican rice borer, Eoreuma loftini (Dyar)

Five weed and forage host plant species and three crop host plant species were ranked by oviposition preference shown by the Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), and nutritonal biochemicals, free amino acids and sugars, in the host plant tissues were quantified in order to determine which of them predicate the observed selection preference. Of the free amino acids, free histidine, which has been identified in other studies as being important to sugarcane, Saccharum hybrids) pests, most closely followed the oviposition preference for sudangrass (Sorghum bicolor [L.] Moensch spp. drummondi [Nees ex Steud.] de Wet & Harlan)>johnsongrass (S. halepense [L.])>barnyardgrass (Echinochloa crus-galli [L.] P. Beauv.) >Vasey's grass (Paspalum urvillei Steud.) >broadleaf signalgrass (Urochloa platyphylla [Munro ex C. Wright] R. Asch. & Graebn.; and among the crops, corn (Zea mays L.)>sugarcane>sorghum (S. bicolor [L.] Moensch). Of the three principal sugars (fructose, glucose, and sucrose), fructose was the most closely associated with Mexican rice borer oviposition preference. Implications of these associations for pest trapping and possible varietal development are discussed.