RESUMO
Hylurgopinus rufipes male and female beetles were attracted to American elms infected with Dutch elm disease, and to American elms killed by injection of cacodylic acid.H. rufipes was also attracted to solvent extracts of elm, or to Porapak Q-trapped volatiles from elm. The major components of attractive fractions of Porapak Q-trapped volatiles were isolated, identified, and tested in field bioassays. Several artificially compounded mixtures of sesquiterpenes were attractive toH. rufipes, although no bait tested was as attractive as diseased tree controls. Laboratory bioassays with H. rufipes were marginally successful. In laboratory bioassays, nine of 14 sequiterpenes identified from active fractions of Porapak extracts elicited significant response from Scolytus multistriatus male and female beetles: δ- and γ-cadinene, α-cubebene, γ-muurolene, and ß-elemene were most active. However, in field tests, none of the sesquiterpenes alone or in combination significantly attracted S. multistriatus, nor did they significantly enhance the attraction of S. multistriatus to female-produced pheromone components (4-methyl-3-heptanol [H] and α-multistriatin [M]). In other field tests, α-cubebene (C) significantly enhanced response of S. multistriatus to H plus M, but foliage, logs, or chips of healthy elm did not enhance trap catch to HMC.
RESUMO
Diseased elms, treated with various doses of cacodylic acid in northwest England, became attractive to elm bark beetles (Coleoptera: Scolytidae). This attraction seemed to be independent of pheromone baits. However attractive the trees became, they were unsuitable to the beetles as breeding sites since significantly more beetles visited the trees than were stimulated to penetrate and attempt to breed. It seems as if colonization of trap trees by the bark saprophytePhomopsis oblonga following cacodylic acid treatment made the trees unsuitable to beetles for breeding.
