A Flavonoid, Luteolin-7-Glucoside, as well as Salicin and Populin, Stimulating the Feeding of Leaf Beetles Attacking Salicaceous Plants

Abstract

Luteolin-7-glucoside was isolated as a feeding stimulant to leaf beetles, Chrysomela vigintipunctata costella and Plagiodera versicolora distincta in addition to salicin from the leaves of Salix gracilistyla. Feeding response of three species of Salicaceae-feeding leaf beetles, C. v. costella, P. v. distincta and Lochmaea capreae cribrata, to the three chemicals, luteolin-7-glucoside, salicin and a salicin derivative, populin, varied species-specifically. Salicin and populin stimulated the feeding in C. v. costella and P. v. distincta but not in L. c. cribrata, while all three species responded to luteolin-7-glucoside.Salicin was found in all Salix species examined, and populin was always accompanied by salicin in the genus Populus. Luteolin-7-glucoside was also distributed in Salicaceae. These results suggest that host specificity of C. v. costella and P. v. distincta depends on the presence of salicin and populin as well as luteolin-7-glucoside. On the other hand, the cue substance in L. c. cribrata seems to be flabonoids such as luteolin-7-glucoside.