Aggregation pheromone components of two species ofPissodes weevils (Coleoptera: Curculionidae) Isolation,identification, and field activity

Two related volatile compounds were identified from each of two species ofPissodes bark weevils and implicated as components of their aggregation pheromones. Grandisol (cis-2-isopropenyl-1-methylcyclobutaneethanol), and its corresponding aldehyde, grandisal, were isolated from males of bothP. strobi andP. approximatus and were found in the abdomens and hindguts of the respective species. In field tests synthetic grandisol and grandisal together with odors from cut pine acted synergistically in attracting both sexes ofP. approximatus. This response was similar to that elicited by maleP. approximatus feeding on cut pine. Males and females of natural populations ofP. strobi were more responsive to caged males feeding on leaders of white pine than they were to leaders alone. The combination of grandisol, grandisal, and leaders was less attractive than males on leaders, but more attractive than leaders alone. From isolation of pheromone components at different times of the year, it was determined that males of both species produced grandisol and grandisal only at times when cohort females were reproductively mature.