“Bug Poop Grows Trees” (BPGT)

By Lee Anna Sherman

In Andrew Moldenke’s forest ecology course, students get the BPGT acronym drilled into their heads from Day One. Oregon’s fabled old-growth forests owe their existence to insect digestion, and the professor wants to make sure nobody forgets it.

“Old, decayed, and decaying logs and other detritus,” Moldenke explains to author Jon Luoma in the 1999 book The Hidden Forest: The Biography of an Ecosystem, “have been ground, digested, and redigested many times over” by relentless legions of hungry arthropods (invertebrates with segmented bodies, external skeletons and jointed limbs).

By the thousands, specimens of these voracious dirt makers — millipedes, mites, centipedes, beetles, springtails, microspiders, pseudoscorpions — are preserved, labeled and catalogued in Cordley Hall, home of the Oregon State Arthropod Collection, one of the most extensive university collections in the United States. The museum’s 6,000 glass-topped drawers, stored in endless rows of stainless-steel cabinets, also hold pollinators — the bees, butterflies and moths that inhabit the forest understory and canopy. Aquatic insects are archived there, too, along with larval insects and those that live in grasslands and deserts. There are water striders, stinkbugs, cicadas, leafhoppers, scorpions, grasshoppers, crickets and conifer pests such as the hemlock wooly adelgid and the spruce budworm. Even insects from a rare, glacier-dwelling order called “ice crawlers” can be viewed in OSU’s bug museum.

This “taxonomic library of arthropod life,” as Luoma calls it, houses the largest repository of Pacific Northwest insects in the world. Among the scientists who pore over the collection are researchers from the H.J. Andrews Experimental Forest, an old-growth research site in the Cascades jointly managed by OSU and the U.S. Forest Service. Bug life can be a “precision barometer” — what Luoma calls an “arthropodmeter” — of site-specific ecological conditions. “A knowledgeable entomologist might, by simply analyzing the species of tiny organisms in a handful of soil, describe in astonishing detail the ecosystem above,” he explains.

Entomologist Chris Marshall, hired in 2005 to manage and curate the collection, has been energetically building upon the existing 3 million samples preserved with pins on archival foam called Polyzote (dry-mounted), on glass slides (slide-mounted) or in borosilicate vials (wet-mounted). His recent expedition to South America, for example, added thousands of specimens to the collection’s tropical holdings. Lab renovations, including new microscopes with fiber-optic lights, nine-digit barcode scanners and a searchable database of the 700-volume library are among the improvements spearheaded by Marshall. The latest: a high-grade digital imaging system purchased with a $70,000 grant from the OSU Office of Research.

“Our goal,” says Marshall, “is to make the collection an increasingly valuable resource for entomologists, forest scientists, geologists and agronomists the world over.”

To arrange a visit to the collection, see osac.science.oregonstate.edu