|Jimenez-gasco, Maria Del Mar|
Submitted to: Oriental Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2012
Publication Date: 4/9/2012
Citation: Geib, S.M., Scully, E.D., Jimenez-Gasco, M., Carlson, J.E., Tien, M., Hoover, K. 2012. Phylogenetic analysis of Fusarium solani associated with the Asian longhorned beetle, Anoplophora glabripennis. Oriental Insects. 7(4):e32990.doi:10.1371 Interpretive Summary: The Asian longhorned beetle is a wood feeding insect that causes tree mortality by feeding and disrupting the vascular tissue in its host. It is not completely understood how this insect feeds and digests wood, but it is likely that it utilizes symbiotic microbes to aide in digestion. A fungal species, Fusarium solani, appears to be associated with the larval stage of this insect. To better understand this relationship, Asian longhorned beetles from several different geographic locations and grown on different host tree species were surveyed for presence of F. solani in their gut. Despite the geographic origin or host tree species surveyed, a unique strain of Fusarium were consistently found to be associated with the beetle gut, suggesting a strong relationship between these organisms. While little is known about the role of filamentous fungi and their associations with insects, this research suggests that the F. solani isolate found in association with larval A. glabripennis has the potential to provide the gut community with wood degrading activity.
Technical Abstract: Culture-independent analysis of the gut of a wood-boring insect, Anoplophora glabripennis (Coleoptera: Cerambycidae) revealed that a fungal species, Fusarium solani, is consistently associated with the larval stage of this insect. Using the translation elongation factor 1-alpha region for phylogenetic and OTU-based analyses, the presence of F. solani was consistently detected in both colony derived and wild A. glabripennis populations, but genetic variance at this locus was low among A. glabripennis-associated isolates. To better characterize the genetic variation of F. solani associated with A. glabripennis and establish its phylogenetic relationship with other F. solani isolates, monoconidial cultures were created from different populations, and phylogenetic analysis was performed using a combination of the translation elongation factor alpha-1, internal transcribed spacer, and large subunit rDNA regions. These analyses revealed that colony-derived larvae reared in three different tree species or on artificial diet, as well as larvae from wild populations collected from four locations in New York City from three additional tree species, and from a single tree species in Worcester, MA, consistently harbored F. solani within their guts. While there is some genetic variation in the strain carried between populations, within-population variation is low. We speculate that F. solani is able to fill a broad niche in the A. glabripennis gut, providing it with fungal lignocellulases to allow the larvae to grow and develop on woody tissue. However, it is likely that many F. solani genotypes could potentially fill this niche, so the relationship may not be limited to a single isolate. While little is known about the role of filamentous fungi and their symbiotic associations with insects, this report suggests that larval A. glabripennis has developed an intimate relationship with F. solani that is not limited by geographic location or host tree.