Intestinal modifications of oak leaf tannins by Lymantria dispar L-(Lep., Lymantriidae) and possible effect on larval development

The mode of action of polyphenols within an insect is not well understood a nd it would be useful to investigate the behaviour pattern of single phenol ic compounds within the gut of an insect in this context. Tn the present st udy, the phenolic composition of the food of the gypsy moth, Lymantria disp ar, was compared with that of its frass by using high-performance liquid ch romatography. The main difference was a shift in the concentration of pheno lics in the frass with short retention times to those with longer ones, whi ch, additionally, resulted in the appearance of new phenolic compounds. The se new phenolics were hydrolysable tannins because after a cleavage via hyd rolysation the hydrolysate contained high amounts of gallic acid. The appea rance of these new phenolics in the frass of the larvae influenced growth n egatively, as there was a negative correlation (P < 0.05) between their con centrations and the growth percentages of the larvae.