ATTRACTION OF BARK BEETLES, TOMICUS-PINIPERDA, HYLURGOPS-PALLIATUS, AND TRYPODENDRON-DOMESTICUM AND OTHER INSECTS TO SHORT-CHAIN ALCOHOLS AND MONOTERPENES

Several Scandinavian forest insects, Hylurgops palliatus, Tomicus piniperda, and Trypodendron domesticum (Coleoptera: Scolytidae), Rhizophagus ferrugineus (Coleoptera: Rhizophagidae) and Pollenia spp. (Diptera: Calliphoridae) were attracted to window traps baited with ethanol and placed on Scots pine trees (Pinus sylvestris) in May-June, 1986. Release of ethanol at increasing relative rates of 0, 0.01, 0.1 and 1.0 (800 mg/day) from the window traps on trees in 1987 caused H. palliatus, T domesticum, and R. ferrugineus to be increasingly attracted, while T piniperda was equally attracted at both 0. 1 and 1.0 rates. The attraction of T piniperda to ethanol was weak compared to attraction to a monoterpene mix, (+/-)-alpha-pinene, (+)-3-carene, terpinolene. The terpene mix plus ethanol was significantly more attractive to H. palliatus than ethanol alone, but terpenes significantly reduced the attraction of T. domesticum to ethanol. Baiting of pipe traps with a series of short-chain alcohols (methanol to hexanol) each alone showed that ethanol was greatly preferred by H. palliatus, T domesticum, and R. ferrugineus over alcohols of one more or one less carbon, while longer-chain alcohols were not attractive. However, Glischrochilus hortensis (Col.: Nitidulidae) was attracted only to propanol. A series of 10-fold increasing release rates of ethanol (0.0001-1.0, where 1.0 = 800 mg/day) with either a "low" or "high" release of the terpene mix had various effects on the sexes during their attraction to pipe traps and subsequent entering of holes. Release of (-)-verbenone at 0.25 mg/day had no significant effect on H. palliatus or R. ferrugineus attraction to ethanol, but the response of T domesticum to ethanol was reduced. Several theories on olfactory mechanisms of host selection by T. piniperda are integrated and placed in ecological perspective.