Substantial destruction of northern hemisphere forests by bark beetles, including the pine engraver beetles ( Ips pini), is a serious concern. We hypothesize that these beetles must have special detoxification enzymes that allow them to tolerate toxic alleochemicals in host tree resin. Many insect detoxification enzymes are cytochrome P450s. Utilizing our expressed sequence tag (EST) library, we sequenced and cloned six different P450 cDNAs.

Interestingly, real time PCR showed that expression of one of these P450 genes, EST 002G06, may be an unidentified enzyme at the end of the pheromone biosynthetic pathway. This enzyme may convert myrcene to the I. pini pheromone, ipsdienol. This hypothesis is supported by the following experimental observations: (I) basal levels of 002G06 are much higher in males than females, (II) 002G06 transcript is upregulated in feeding males, (III) 002G06 transcript is upregulated in juvenile hormone III treated males, and (IV) preliminary molecular modeling of 002G06 shows that myrcene is a potential substrate for this P450 enzyme.

Experiments to further characterize 002G06 and other potential detoxification P450s are underway. Molecular modeling and functional assays will identify the substrates for these P450s.