Grant: Discovery Grants Program - Individual

Trees wage chemical warfare upon the herbivorous insects that try to feed on them.  For instance, when  bark beetles attack a tree, the tree immediately begins to spread resin, which contains toxins, onto them.  As the attack by the beetles continues, the tree is often able to respond by manufacturing new resin chemicals that are even more toxic in an effort to kill the beetles or to drive them out.  Often, however, the beetles prevail in their attack and the tree is killed, because the beetles have evolved enzymes that effectively detoxify the resin chemicals.  Some of these enzymes are called "cytochromes P450" and any given insect species likely has many different varieties of these enzymes, which each help it to detoxify different plant chemicals.  The intent of my research is to discover the cytochromes P450 that are important to bark beetles attacking conifers.  I intend to both identify cytochrome P450 genes that the beetles "turn on" to produce the detoxification enzymes and to characterize the mechanisms by which the enzymes detoxify the tree resin chemicals.  With this knowledge, it might be possible to design pesticides that inhibit specific enzymes in only certain species of bark beetles.  This type of pesticide would make the beetles more susceptible to the host tree toxins, and thus the tree could "win" the battle with the beetles more often. Since the pesticide would be designed to be very specific to just one or two enzymes in a particular species of beetle, it would not have effects on other important forest organisms.  In addition, a better understanding of which resin chemicals are sufficiently dangerous that a bark beetle will expend considerable energy to detoxify the compound will assist tree breeders in their efforts to produce conifers that are more resistant to bark beetle attack.