Photos from the WFIWC Archives:
Mexico
Figure A. From left: Furniss on stump of "The Devil," David Cibrián, Edgardo Hernandez, Armando Delgado. A strip of bark was removed to facilitate felling because the saw had a 24-inch blade, well short of the tree radius.
{This is the fourth of four entries; view the first, second or third entry.}
Return to Chihuahua, Mexico - 1977. In April 1977, David Cibrián and Edgardo Hernandez of the University of Chapingo, Mexico, and I visited the location in Chihuahua where I had discovered the Douglas-fir beetle in 1974 (see previous account). We traveled in my camper truck, which was outfitted with a "motor sierra" for falling trees, axes, assorted collecting gear, and containers for bringing back live Douglas-fir beetles (under permit) for a mating test with Idaho beetles.
Figure B. Downed Devil. I took 12, 1-sq-ft bark samples at ten-ft intervals along the stem and collected 400 live Douglas-fir beetle brood for a mating test with Idaho beetles.
East of La Magdalena, we located a large, 212-year-old, infested tree and I proceeded to fall it. However, it was already a bit late so I quit after removing a strip of very thick bark to lessen the diameter and putting in the undercut. In the next morning, I eventually felled the monstrous tree (photos A, B), which my buddies were now jokingly calling "El Diablo," and I collected several hundred adult beetle progeny. I also took bark samples for comparison with data from Idaho. A mix of similarities and differences was apparent. For example, it was evident that the braconid parasite, Coeloides vancouverensis, so common in the U.S., was absent in this and other trees that we felled.
Figure C. Mating of Idaho X Idaho beetles produced egg galleries with 10-13 alternate groups of eggs; Mexico X Mexico matings produced egg galleries having only 3-4 such groups in galleries of similar size (D). This difference led to anatomical studies and describing the Mexican population as a sub-species after Lauro Barragan who guided me in 1974 when the beetle was found in Mexico.
After returning to Idaho, I replicated a test of the "intra-specific" and reciprocal crosses. Cross-mated beetles from Chihuahua and Idaho produced 67% fewer progeny than did pairs of beetles from within either locality (Furniss & Cibrián Tovar 1980, Furniss 1981). Upon examining the galleries of Mexican pairs and Idaho pairs, another striking difference was seen. The number of times a female crossed her gallery to deposit a series of eggs was consistently greater for Idaho pairs (10-13, photo C) than for Mexico pairs (3-4, photo D) for galleries of comparable length. The galleries of scolytids are characteristic for each species; such a distinct difference is indicative of considerable genetic drift between the disjunct populations involved. Later, I compared their anatomical features and described the Chihhuahau population as the sub-species D. pseudotsugae barragani (Furniss 2001) after Lauro Barragani of San Juanito who guided me during discovery of this beetle in Mexico in 1974 (see previous account). -- Malcolm M. Furniss
References
Furniss, M.M. 2001. A new subspecies of Dendroctonus from Mexico. Ann. Entomol. Soc. Am. 94:21-25.
Furniss, M. M. 1981. Pruebas de cruzamiento entre poblaciones de Dendroctonus pseudotsugae Hopk. procedentes de Chihuahua, Mex. e Idaho EUA. Proceedings 1 Simposio Nacional sobre Parasitologia Forestal, Uruapan, Mich., Mexico, 18 y 19 de Febrero, 1980. p. 178-186.
Furniss, M. M. and D. Cibrián Tovar. 1980. Compatibilidad reproductiva e insectos asociados a Dendroctonus pseudotsugae (Coleoptera: Scolytidae) de Chihuahua, Mexico e Idaho, E. U. A. Folia Entomologica Mexicana No. 44:129-142.
{This is the fourth of four entries; view the first, second or third entry.}
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