Photos from the WFIWC Archives:
Equipment and Methodology
From left: Paul Tilden, Lloyd Browne, and Dave Wood rolling up a sticky coated plastic screen vane removed from a pheromone-baited trap. The entrapped western pine beetles and other insects were removed for identification and counting by immersing the vane in heated solvent. (M. Furniss photo)
Western pine beetle pheromone trap-out, 1970. In 1970, only a few years after the first scolytid aggregative pheromone was discovered, a robust "trap-out" experiment involving the western pine beetle (Dendroctonus brevicomis) was implemented near Bass Lake on the Sierra N.F., California. Hundreds of sticky traps baited with a mixture of pheromones (exo-brevicomin and frontalin) and myrcene (a pine resin monoterpene) were deployed throughout an infestation encompassing 35 square miles. At the time, I was experimenting with Douglas-fir beetle pheromones (including frontalin) in Idaho and arranged to visit the California test, during which I took the accompanying photos. I bunked at the Miami Field Base (see related Facilities item), just south of Yosemite National Park. Bill Bedard (W.D. Bedard, Jr.) was one of the researchers involved with the test and was stationed there at Miami with the Forest Service. Other researchers involved in the test were David L. Wood, Lloyd Browne, and Donald L. Dahlsten, of the University of California, Berkeley.
Bill Bedard dismantling a 4-vane pheromone trap. A mixture of two attractant pheromones and a host volatile was eluted from vials within an inverted "salt shaker" container. The sticky-coated plastic screen vanes were rolled up and carried in a card- board box mounted on a pack board. Some 350 such traps were deployed in this test. (M. Furniss photo)
At the outset, I need to emphasize a couple of points. This was, I believe, the biggest such endeavor ever undertaken and it was well designed in all its technical aspects. However, for reasons that I still don't understand, it fell flat in the reporting stage. I know of no subsequent publication; this brief account is gleaned from WFIWC proceedings (1970 and 1971). I encourage surviving participants to provide me with their recollections. Why were the results not published? Here are excerpts from the cited proceedings:
"Populations of the beetle and its insect natural enemies and associates are being measured throughout the 35 sq. mile study area for four successive generations, one preceding suppression and three following. Over 250 suppression traps were erected in four one-half square mile suppression plots on an eight-chain grid. Over 100 survey traps were placed throughout the study area on a 40-chain grid. Traps were erected before spring emergence, and suppression traps were removed at end of spring flight, while the survey traps remained out for the duration of the entire flight season."
"Suppression: Four one-half-square-mile treatment areas and two one-square-mile check areas will be established. Traps will be established on 8-chain (528 ft) centers in each of the four treatment areas. At each trap, exo-brevicomin, frontalin, and myrcene will evaporate from glass vials at the rate of 10 mg/day in a 1:1:1 ratio during the spring emergence period.
Survey: Traps will be established on 40-chain centers throughout the 35-square-mile infestation area. At each trap, exo-brevicomin, frontalin, and myrcene will evaporate from glass vials at the rate of 1 mg./day in a 1:1:1 ratio throughout the entire flight season."
Bedard reported the following at the 1971 WFIWC: "The data are not completely gathered and only partially analyzed, but these preliminary results are available. We started with over 100 infested trees before the treatment. Now, two generations after suppression treatment, we have located only five infested trees. Suppression traps trapped 427,000 western pine beetles while the survey traps caught 330,000. One hundred and fifty trees were attacked adjacent to suppression traps, but only 15 or so were killed. We feel these preliminary results are very promising."
With that, I can find no further reference to this historical endeavor. -- Malcolm Furniss
References
Panel: Field testing attractants. Proceedings 21st WFIWC , Seattle, WA, 1970.
Panel: Bark beetle attractant tests of 1970. Proceedings 22nd WFIWC, Glenwood Springs, CO, 1971.
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