Terpenoid Resin Distribution in Conifer Needles with Implications for Red Tree Vole, Arborimus longicaudus, Foraging

Tree voles are dietary specialists, feeding almost exclusively on conifer needles and bark. They reduce their exposure to conifer chemical defenses by physically removing resin ducts from many needles before ingesting the remaining tissue. The portion of needle removed differs among tree species, depending on the location of the resin ducts. To evaluate the amount of resin avoided by this behavior we removed the resin ducts from Douglas-fir, Western Hemlock, and Sitka Spruce needles and used gas chromatography to compare volatile resin concentrations in needles with and without the resin ducts removed. Needle tissues without resin ducts contained no terpenoid resin, demonstrating that tree voles can regulate the nutritional quality of their diet by controlling the amount of resin ingested. We suggest that differences in the physical structure (and possibly chemical composition of terpenes) of the needles make it difficult for voles to easily switch between tree hosts

Ethanol and acetone from Douglas-fir roots stressed by Phellinus sulphurascens infection: Implications for detecting diseased trees and for beetle host selection

Phellinus sulphurascens (previously the Douglas-fir form of Phellinus weirii) is an important native pathogen causing laminated root rot in forests of western North America. Visual crown symptoms, or attacks by bark or ambrosia beetles appear only during advanced stages of the disease with extensive infection in the lower bole. Ethanol synthesis is one of many physiological responses in tree tissues stressed by pathogens. Ethanol, acetone and other volatiles from root tissues of healthy and diseased trees were analyzed using headspace gas chromatography. Xylem and phloem from 20 diseased trees at two western Oregon sites contained higher concentrations of ethanol, acetone, or other headspace volatiles than 20 healthy trees on one or more dates in September, November, or the following May. Root cross-sections from eight diseased trees were sampled along perpendicular transects and found to contain extremely variable ethanol concentrations, with highest xylem quantities in a 0–2 cm zone outside the infection boundary and lowest amounts inside the infection. Acetone concentrations were the opposite. Logistic regression models were built and tested to determine which volatiles could predict diseased trees. A model using xylem ethanol concentrations as the only parameter was selected and validated with measurements from 80 trees on the edges of P. sulphurascens infection centers at two different western Oregon sites. This model successfully predicted trees with laminated root rot (78% overall correct classification and 68% for known diseased trees), but worked best for those with infections observed in both root cores and the root collar (100% correct). Early detection of P. sulphurascens infected trees remains a challenge. Our ethanol analysis method is useful for research, but provides limited benefits for identifying individual P. sulphurascens hazard trees, or for extensive ground surveys in the forest. Whether ethanol is released to the atmosphere in sufficient quantities to confirm infection before the late appearance of crown symptoms, or bark beetles remains unknown. If it is, then development of sensors capable of tree side detection requiring minimal tissue sampling would be useful in managing this disease. We also propose a mechanism for how ethanol with host monoterpenes could play a central role in pioneering bark beetle primary host selection of trees infected with this pathogen.Keywords: Root disease detection, Laminated root rot, Pseudotsuga menziesii, Beetle primary attraction, Tree stress, Phellinus weiri

Ethanol Attracts Scolytid Beetles to Phytophthora ramorum Cankers on Coast Live Oak

Ethanol in sapwood was analyzed along vertical transects, through small spot cankers and larger basal cankers, of Phytophthora ramorum-infected stems of Quercus agrifolia at three sites in California. Trees with large basal cankers, known to attract scolytid beetles, had a 4.3 times higher ethanol level than trees with spot cankers that attract fewer beetles. Ethanol concentrations inside cankers, where scolytid beetles preferentially attack, varied by about four orders of magnitude among samples, with a median level of 16.0 mu g.g(-1) fresh mass. This concentration was 4.3 and 15.5 times greater, respectively, than the concentrations at 1 cm or 15-30 cm outside the canker boundaries. In the laboratory, we demonstrated that ethanol escaped through the bark of a Q. garryana log just 3 days after it was added to the sapwood. At the three study sites, traps baited with ethanol captured more Xyleborinus saxesenii, Pseudopityophthorus pubipennis, and Monarthrum dentiger (all Coleoptera: Curculionidae: Scolytinae) than traps baited with ethanol plus (-)-alpha-pinene, or ethanol plus 4-allylanisole (4AA). Logs of Q. agrifolia with a 50 % ethanol solution added to the sapwood were placed at the study sites, with or without additional bark treatments above the ethanol. The number of scolytid beetle gallery holes above the ethanol-infused sapwood was 4.4 times greater than that on the opposite side of the log where no ethanol was added. Attachment of ultra-high release (-)-alpha-pinene pouches to the bark surface above the 50 % ethanol solution reduced scolytid attacks to a density of 19.1 % that of logs without this treatment. We conclude that ethanol in P. ramorum cankers functions as a primary host attractant for scolytid beetles and is an important link in colonization of these cankers and accelerated mortality of Q. agrifolia. The results of this research shed light on the chemical ecology behind the focused scolytid attacks on P. ramorum-infected coast live oaks, and lay the groundwork for future efforts to prolong the survival of individual trees of this keystone species.Keywords: Ethanol, Quercus agrifolia, Phytophthora ramorum, Deterrents . (−)-α-Pinene, Ambrosia beetles, Sudden oak death, Bark beetles, 4-Allylanisol

Rapid Extraction of Sesquiterpene Lactones from Sagebrush for Use as Taxonomic Markers

The sesquiterpene lactones of sagebrush occur in glandular trichomes on the leaf surface and can be extracted in 1 to 2 minutes with chloroform. Analysis of this extract by thin-layer chromatography can be used as a taxonomic characteristic.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Ethanol in ponderosa pine as an indicator of physiological injury from fire and its relationship to secondary beetles

Sixteen days after a September wildfire, ethanol and water were measured in phloem and sapwood at breast height and the base of Pinus ponderosa Dougl. ex P. & C. Laws. with zero (control), moderate, heavy, and severe crown scorch. The quantity of ethanol increased with each level of injury, resulting in trees with severe scorch containing 15 and 53 times more phloem and sapwood ethanol, respectively, than controls. Ethanol concentrations in the sapwood and adjacent phloem were related, probably as a result of diffusion. Upward movement in xylem sap was most likely responsible for the relationship between sapwood ethanol concentrations at breast height and the stem base. As trees recovered from their heat injuries, the ethanol concentrations declined. In contrast, ethanol accumulated in dead trees that lost their entire crowns in the fire. Various bark and xylophagous beetles landed in greater numbers on fire-damaged trees than on controls the following spring and summer, suggesting that ethanol was being released to the atmosphere and influencing beetle behavior. Beetle landing was more strongly related to sapwood ethanol concentrations the previous September than in May. Sapwood ethanol measured 16 days after the fire was the best predictor of second-year mortality for trees with heavy and severe crown scorch

Ethanol in Douglas-fir with black-stain root disease (Leptographium wageneri)

Diseased and healthy Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) were identified at two black-stain root disease centers, caused by Leptographium wageneri var. pseudotsugae Harrington & Cobb, in the Oregon Coast Range near Coos Bay. Phloem and sapwood near the root collar were sampled monthly for 1 year, whereas roots were sampled in October and November. Ethanol concentrations in sapwood of diseased trees near the root collar were 4–24 times higher than in healthy trees for all months of a year, except January and June. Roots from diseased trees in October had 5 times more ethanol in the phloem and 19 times more ethanol in the sapwood than corresponding tissue from healthy trees. Ethanol concentrations in roots from diseased trees in November were no different from October. Within trees, ethanol concentrations varied substantially among positions around the root collar and among different roots. Ethanol may play an important role in the biology of L. wageneri and beetle–pathogen interactions in Douglas-fir. Ethanol also may be useful in detecting stressed or diseased trees