Semiochemicals for the larger pine shoot beetle (Tomicus piniperda L.) and its clerid predators

The impact on Scots pine in New York State and the chemical ecology of Tomicus piniperda (L.)(Col., Scolytidae) were studied. Using dendrochronological techniques it was estimated that shoot feeding by T. piniperda caused 50% reduction of the average annual basal area increment of Scots pine. Over a seven-year period trees with severely damaged crowns increased their basal area 37% less than that of trees with moderately damaged crowns. The chemical ecology of T. piniperda was investigated using various laboratory and field techniques. A highly sensitive system, coupled gas chromatography-electroantennography (GC-EAD), for the detection of insect semiochemicals was implemented. Beetle/host odors were sampled throughout the year and analyzed by GC-MS and GC-EAD. Tomicus piniperda can antennally perceive 30 of more than 100 compounds present in aeration and hindgut extracts, including four monoterpenes, one epoxide, two aldehydes, 11 alcohols, five ketones, carbon dioxide and six unidentified compounds. Five compounds are beetle-produced or induced by beetle boring activity. The composition of antennally active compounds during spring reproductive flight was examined with multivariate statistics. Discriminant function analysis separated aeration extracts from female-, male- and non-infested Scots pine into three distinct groups. Factor analysis separated aerations from days 1-3 of female- and from days 2-5 of male-infested Scots pine suggesting that pheromone emission takes place during the early stage of female boring activity. The behavioral responses of T. piniperda were tested in the field by capturing beetles in multiple funnel traps. All compounds were tested for synergism or inhibition to the host attractant, {dollar}alpha{dollar}-pinene. Alpha-pinene oxide, nonanal, trans-verbenol, and myrtenol synergized, and fenchone and cis-3-pinene-2-ol reduced T. piniperda attraction to {dollar}alpha{dollar}-pinene. Ethanol, released at the rates 3-300 mg/day, also synergized attraction to {dollar}alpha{dollar}-pinene. Moreover, attraction to {dollar}alpha{dollar}-pinene and ethanol appears to be temperature dependent. The kairomonal activity of T. piniperda-associated compounds was tested in two predatory beetles, Thanasimus dubius and Th. formicarius (Col., Cleridae). Tomicus piniperda-associated compounds elicited stronger antennal responses in both clerids than Scots pine monoterpenes. Both clerids were attracted by {dollar}alpha{dollar}-pinene oxide, fenchone, trans-4-thujanol, and myrtenal when tested in a low speed wind tunnel.