Effects of varying ethanol and turpentine levels on attraction of two pine root weevil species, Hylobius pales and Pachylobius picivorus (Coleoptera: Curculionidae)

The pales weevil, Hylobius pales (Herbst), and the pitch-eating weevil, Pachylobius picivorus (Germar), are part of a weevil complex causing extensive damage to plantation pines throughout the Lake States. A means of monitoring weevil populations has been developed using pitfall traps baited with ethanol and turpentine. The relative attractiveness of six combinations of ethanol and turpentine were compared. Traps were monitored throughout the 1988 and 1989 growing seasons in a Scots pine Christmas tree farm. Both species were more strongly attracted to ethanol/turpentine ratios above 1:1. Pales weevils preferred slightly higher ethanol/turpentine ratios than did pitch-eating weevils. Within species, both sexes responded equivalently among treatments. The implications of these behavioral responses to weevils' locating stressed trees, the role of chemical ecology in niche partitioning, and IPM of pine root weevils are discussed.