Diterpene acids are plant defense compounds which are not volatile. I wonder wthether diterpene acid exist in the hind gut of a bark beetle who eat phloem of pints.
page 189 in: Andreas Schaller. 2008. Induced Plant Resistance to Herbivory Springer Science & Business Media,Pp. 462. ISBN1402081820, 9781402081828
http://www.ncbi.nlm.nih.gov/pubmed/26003180
Gerald A. Rosenthal, May R. Berenbaum. 2012. Herbivores: Their Interactions with Secondary Plant Metabolites: The Chemical Participants Academic Press,Pp.452. ISBN032313940X, 9780323139403Hoping this will be helpful
I have read a very interesting and recent chapter on bark beetles and although this is far away from my field but I think it will be useful to your research. It mentioned the role of broad array of microbial symbionts that benefit beetles in many ways including assistance in procuring nutrients from phloem, a direct nutritional substrate and assistance
in overcoming tree defenses through detoxification.
Thanks for all of you. Diterpene acids are constitutive chemical defense of host plants and they will also be induced by bark beetles and fungus. I have extract diterpene acids from phloem of fresh stump.
Article Rapid Induction of Multiple Terpenoid Groups by Ponderosa Pi...