Variation in concentration of phenolic acid derivatives and quercetin glycosides in foliage of cranberry that may play a role in pest deterrence

Abstract

Several insect herbivores have been anecdotally reported to prefer 'Howes' cranberry leaves (Vaccinium macrocarpon) over those of 'Early Black'. A series of studies were undertaken to determine whether these anecdotal reports are accurate and to compare phenolic profiles in the foliage of 'Early Black' and 'Howes' for compounds that differ in concentration and could be further investigated as possible feeding deterrents. Gypsy moth larvae (Lymantria dispar) demonstrated a significant feeding preference for 'Howes' over 'Early Black'. Red-headed flea beetle adults (Systena frontalis) demonstrated a similar but not statistically significant trend, whereas cranberry weevil (Anthonomus musculus) did not prefer either cultivar. Compounds giving rise to six peaks in the phenolic profile were significantly greater in concentration in 'Early Black' than 'Howes' on at least one of three sampling dates during the growing season. Five of these compounds were isolated from leaves harvested at the June time point coinciding with gypsy moth infestation and identified as: 5-O-caffeoylquinic acid, 3-O-p-coumaroylquinic acid, 5-Op-coumaroylquinic acid, quercetin-3-O-galactoside, and quercetin-3-O-rhamnoside.