Dr. Rachel K. Osborn
Evolution, Scolytinae, invasive species, symbiosis, ambrosia beetles.
I was first drawn to study symbiosis as an undergraduate when I learned about the complex relationship between fungi and attine leafcutter ants. I was fascinated by how two vastly different organisms as fungi and insects could maintain a mutually beneficial symbiosis. My intrigue deepened when I learned that two other insect groups (macrotermitine termites, and ambrosia beetles from the weevil subfamilies Scolytinae and Platypodinae) also live with symbiotic fungi. Of all these, ambrosia beetles are the most compelling because they contain multiple repeated independent origins of symbiosis with a variety of different fungi.
This interest brought me to Michigan State University where my dissertation research focused on the diversity of ambrosia beetles from the scolytine tribe Xyleborini and the identities of their fungi in South America. Most of the current knowledge on the diversity of xyleborine beetles and their fungi centers around species found in North America, Asia, and Europe. Little is known about the ambrosia partnerships in the Neotropics even though it is a global center of diversity for these weevils. I completed surveys throughout Ecuador to collect ambrosia beetles and fungi and used molecular analyses to reveal that several Coptoborus species associate with Fusarium fungi from the ambrosia Fusarium Clade (AFC). Morphological examination of some South American xyleborine specimens previously classified as Coptoborus spp. suggested a high similarity to Xyleborus spp. from Africa. Phylogenetic analysis of these South American and African beetles as well as morphological assessment of additional specimens necessitated the designation of a new genus Xenoxylebora gen. nov. containing species endemic to both continents. This unusual distribution demonstrates the ability of these ambrosia beetles to survive long-distance trans-oceanic dispersal.
My PhD research relied heavily on entomological collections. I used loaned specimens to accomplish my taxonomic research and collaborated with local museum staff to complete my field expeditions in Ecuador. I believe than insect collections are a vital key to unlocking more knowledge about life on Earth. They are irreplaceable repositories for biodiversity on our planet and attract interest from a variety of people. Yet the individuals who are generally granted access to collected specimens often do not fully represent the diversity of communities in which the collections are located. I believe that as caretakers of important entomological collections, we cannot forget our duty to widen the circle of who has access to these important resources.