European spruce bark beetle

Bark beetles oxidise toxic monoterpenoid hydrocarbons in their respiratory air, which originate from the resin of the tree they colonise, and thereby circumvent this defense barrier of the tree. Converting these compounds into less toxic secondary metabolites serves another purpose, by providing pheromones to attract insects of the same species, of both sexes. Therefore, an oxygen function is often introduced species-specifically and stereoselectively. European spruce bark beetles oxidise (-)-a-pinene to (S)-cis-verbenol, whereas pine beetles produce (R)-trans-verheno. In the California fivespined engraver Ips paraconfu-sus), myrcene is converted into (S)-ipsdienol and (S)-ipsenol. But Ips pint and Ips paraconfusus are also able to synthesise their pheromones de novo via the classical mevalonate biosynthetic pathway. 

Fig. 94.3 Conifer tree defense against bark beetles with induced resin production, (a) Resin flow on Norway Spruce (Picea abies) bark after attack by bark beetles, (b) The European spruce bark beetle Ips typographus), the most serious bark beetle pest of Norway spruce, attacking spruce bark with phoretic mites, which are probably involved in the transmission of fungal tree pathogens...

B) Western balsam bark beetle, Dryocoetes confusus formation of endo-brevicomin [(1 F ,5S,7S)-7-ethyl-5-methyl-6,8-dioxabicyclo[3.2.1 ]octane] from ( )-6-nonen-2-one (Vanderwel et a/., 1992a) (C) Spruce beetle, Dendroctonus rufipennis formation of frontalin [(1S, 5fl)-(-)-1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane] from 6-methyl-6-hepten-2-one (Perez ef a/., 1996 Francke etai, 1995 Francke and Schulz, 1999) (D) European elm bark beetle, Scolytus multistriatus hypothetical formation of oc-multistriatin [(1 S,2F ,4S,5F )-(-)-2,4-dimethyl-5-ethyl-6,8-dioxabicyclo[3.2.1]octane] from 4,6-dimethyl-7-octen-3-one (Francke and Schulz, 1999) and E The colored... 

Another company (624, 625) supplies a controlled release dispenser, which is a three-layer plastic laminated sheet consisting of a bottom protective layer, a middle pheromone reservoir layer, and a top permeable layer through which the pheromone diffuses. The sheet can be cut into ribbons and applied over an area. Formulations have been field tested on a number of insect pests gypsy moth, pink bollworm, peachtree borer, lesser peach tree borer, soybean looper, cabbage looper, European elm bark beetle, tobacco budworm, fall armyworm, tussock moth, eastern spruce budworm, and Mediterranean fruit fly. 

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