United States Department of Agriculture D E E P R A U R T LT MENT OF AGRICU Forest Service PNW Pacific Northwest Research Station INSIDE Pitting Extracts Against Pests............................ 2 Combating a Cloud-Riding Forest Pathogen................................................. 3 Information From the Forest............................ 4 FINDINGS issue one hundred ninety four / march 2017 “Science affects the way we think together.” Lewis Thomas Northwest Forest Plants Defeat Pests and Diseases! IN SUMMARY Societies use biologically active chemi- Ellen Goheen Ellen cals as medicines and pesticides to protect human and agricultural health. But wide- spread use of synthetic compounds raises concerns about their safety, and resistance development in targeted pests. To find safer alternatives, scientists turned to native plants and trees in Pacific North- west forests using multiyear exploratory surveys. Researchers collected samples from different plant and tree parts for extraction and toxicity testing with a sim- ple brine shrimp bioassay. These bioassays detected strong biological activity in heart- wood extracts from four cedar and one juniper species. In followup experiments, researchers dis- covered that heartwood extracts from yellow-cedar (Callitropsis nootkatensis), incense cedar (Calocedrus decurrens), Port Orford cedar (Chamaecyparis lawsoniana), Volunteers from the Oregon Youth Conservation Corps spread western redcedar heartwood chips on and western juniper (Juniperus occidenta- a trail in the Rogue River-Siskiyou National Forest. A case study indicates that a chemical compound lis) had strong toxicity or repellent activity in the redcedar chips may reduce the invasive plant pathogen that causes sudden oak death and can be toward mosquitoes, ticks, or fleas. A pat- spread by hikers who have walked through an infected area. ent was issued for compounds with activity toward these pests. It has been licensed to a company interested in developing them chemistry at Oregon State University (OSU), “All our wisdom is stored into commercial products. in the trees.” they realized they were doing similar work. In other experiments, researchers found ―Santosh Kalwar, poet That was just the beginning. extracts and compounds from cedar heart- Karchesy was collecting plants in diverse wood possess strong antimicrobial activity n the early 1990s, Rick Kelsey, a landscapes—from temperate rainforests against Phytophthora ramorum, the patho- research forester with the Pacific to semiarid shrub-steppes—and preparing gen causing sudden oak death. To mitigate I Northwest (PNW) Research Station, was extracts for testing. Both scientists were keen movement of P. ramor um spores by hik- busy investigating whether extracts from vari- on finding natural alternatives to modern ers and cyclists, forest health specialists ous native or introduced plants could repel drugs or pesticides, many of which are made have used western redcedar (Thuja plicata) forest insects or deer from feeding. When from petrochemicals and often have undesir- heartwood chips on a popular hiking trail Kelsey met Joe Karchesy, a professor of wood able side effects. on the Rogue River-Siskiyou National For- est, where retreatment continues to show promising results. Most native plants and trees defend them- selves from diseases and insects by producing KEY FINDINGS their own protective substances. Tree chemists like Kelsey and Karchesy call these “bioac- • Strong biological activity was detected in extracts from 13 forest plant species and tive” chemical compounds, because these moderate activity from another 27 species from a total of 128 tested. substances have effects on living organisms, tissues, or cells. The researchers were eager • Heartwood extracts from four species of cedar and one juniper species showed strong to discover native plants in Northwest forests biological activity, indicating the compounds within the extract might be useful to that could yield new bioactive compounds that humans, perhaps as medicine or pesticides. These results led to more thorough follow- would protect humans, animals, trees, or agri- up studies. cultural products. Kelsey and Karchesy both viewed the forest as • Extracts of cedar or juniper heartwood, and individual compounds in the heartwoods a vast library. Karchesy would say, “Each tree have strong antimicrobial activity against Phytophthora ramorum, the microbe causing is like a book. If you bother to read that book sudden oak death. and do the research, you might find something of value.” Karchesy had been reading his way • Compounds from the heartwood of yellow-, incense, and Port Orford cedars, and west- through the forests and rangelands of western ern juniper also demonstrated strong toxicity or repellent activity toward mosquitoes, and central Oregon and western Washington. He ticks, or fleas that affect animal and human health. Some have effectiveness compara- had also been collecting plant and tree tissues. ble to conventional pesticides. “I was curious,” he says. “People around the world use various extracts of forest plants for medicine. We’d sample the heartwood, extracts, like miners using canaries in coal immediately published, instead it was used as the sapwood, the inner bark, the outer bark, mines to detect lethal gases. “You’re using this a guide for further experiments. Discovery of the needles; it was all very exploratory.” live organism as a test,” Karchesy says. “It bioactivity toward brine shrimp was just the Kelsey’s extraction procedure was similar to either kills it or it doesn’t.” If it did, that meant beginning. Further bioassays of the extracts, Karchesy’s, so they decided to collaborate and the extract contained bioactive compounds. and compounds in the extracts, were needed with other organisms. But where to start? It combine their collection of plant specimens. Kelsey and Karchesy’s forest surveys and was not an easy, straightforward task. The researchers, along with Karchesy’s bioassays covered 128 species of plants and students and postdocs, spent many hours trees. Of these, they detected strong bioactive “But, there was a high probability it would preparing extracts and isolating chemical compounds from 13 species and moderate have activity in some other systems, and by compounds from hundreds of specimens. bioactive compounds from 27. The researchers that we mean potentially insects, pathogens, Karchesy’s daughter Yvette performed the detected strong biological activity in heart- or other animals,” Karchesy says. “It was bioassays—short for biological assessment— wood extracts from four species of cedar and somehow impacting the shrimp’s metabolic where brine shrimp were exposed to the one juniper species. When these initial bioas- processes and subsequently it likely would says were completed, the information was not have some activity against other organisms.” Species and their tissues with strong toxicity in the brine shrimp bioassay, listed in Purpose of PNW Science Findings descending order of activity To provide scientific information to people who make and influence decisions about managing Species Common name Active tissue land. Angelica arguta Sharptooth angelica Roots PNW Science Findings is published monthly by: Callitropsis nootkatensis Yellow-cedar Inner bark, foliage, heartwood Pacific Northwest Research Station USDA Forest Service Leucanthemum vulgare Oxeye daisy Aerial tissue P.O. Box 3890 Oplopanax horridum Devil’s club Root and stem barks Portland, Oregon 97208 Chamaecyparis lawsoniana Port Orford cedar Heartwood Send new subscriptions and change of address information to: [email protected] Pitting Extracts Against Pests Rhonda Mazza, editor; [email protected] Karchesy recalls, “When the survey began interested in testing the cedar and juniper Cheryl Jennings, layout; [email protected] there was interest in Lyme disease, a tick- heartwood extracts on some pests. Science Findings is online at: http://www. vectored pathogen, and West Nile virus, Karchesy sent the CDC some extracts and fs.fed.us/pnw/publications/scifi.shtml a mosquito-borne pathogen.” Karchesy they got back to him, quite excited. They said, also recalls that during his surveys, he met To receive this publication electronically, “Wow, these extracts are very active. Send American Indians carving canoes out of west- change your delivery preference here: more! Isolate the compounds!” he recalls. He ern redcedar (Thuja plicata) trees and saving ended up collaborating with CDC researchers http://www.fs.fed.us/pnw/publications/subscription. the shavings to use as flea control in their dog shtml Nicholas Panella, Marc Dolan, and others on beds. So, he contacted the Center for Disease bioassays that pitted extracts from yellow- Control (CDC) in Fort Collins, Colorado, and United States Forest cedar (Callitropsis nootkatensis) with deer Department Service told them about his bioassays. They were very of Agriculture 2 Joe Karchesy The structure of nootkatone, one of the bioactive sesquiterpene (15 carbons) com- The stump of a yellow-cedar tree showing the yellow heartwood pounds found in yellow-cedar heartwood, also occurs in grapefruit. Researchers that contains the bioactive compounds. Once beneficial com- found it repels ticks, and when combined with another heartwood compound, carva- pounds have been identified, they often can be created in a crol, suppressed growth of mosquito and tick larvae. laboratory, eliminating the need to obtain them from trees. ticks, known carriers of the bacteria that Combating