Host-Tree Monoterpenes and Biosynthesis of Aggregation Pheromones in the Bark Beetle Ips paraconfusus

Figure 2

Proposed scheme for the conversion of the host tree compound, myrcene, to the pheromone components (S)-(−)-ipsenol and (S)-(+)-ipsdienol in Ips paraconfusus based on radio-labelling experiments and enantiomers found in the male [5, 7–12, 17, 19]. Conversion arrows with question marks have not been proven. (R)-(−)-ipsdienol does not accumulate in the hindgut but may occur as an enzyme-bound intermediate. However, contrary to the scheme, the amounts of ipsenone, (S)-(−)-ipsenol and (S)-(+)-ipsdienol in males were not correlated with myrcene titres in the host trees.