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ARS Home » Southeast Area » Miami, Florida » Subtropical Horticulture Research » Research » Publications at this Location » Publication #316849
Title: Geographic variation in mycangial communities of Xyleborus glabratus

Author
item CAMPBELL, ALINA - University Of Florida
item PLOETZ, RANDY - University Of Florida
item DREADEN, TYLER - University Of Florida
item Kendra, Paul
item Montgomery, Wayne

Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/7/2016
Publication Date: 9/1/2016
Citation: Campbell, A., Ploetz, R., Dreaden, T., Kendra, P.E., Montgomery, W.S. 2016. Geographic variation in mycangial communities of Xyleborus glabratus. Mycologia. 108(4):657-667.

Interpretive Summary: Interpretive summary The redbay ambrosia beetle (RAB) is an exotic wood-boring pest that vectors laurel wilt, a lethal disease of American trees in the laurel family, including native forest species and commercial avocado. The disease is caused by Raffaelea lauricola, one of several fungal symbionts carried by RAB (in specialized pouches called mycangia) and introduced into host trees. Little is known about the fungal communities within RAB mycangia, and what factors influence the species diversity and abundance. Scientists at the USDA-ARS (Miami, FL) collaborated with plant pathologists from the University of Florida to study the fungal symbionts carried by RAB collected in north, central, and south Florida. Six species of Raffaelea were found, with R. lauricola the predominant symbiont. However, there were significant differences in the quantity of R. lauricola recovered from beetles at the three sites, suggesting that climate and host tree species may affect the abundance of pathogenic fungi in RAB mycangia. This research improves our understanding of the complex relationships among RAB, its fungal symbionts, and host trees, and may potentially lead to development of methods to manipulate RAB mycangial communities and reduce the spread of R. lauricola.

Technical Abstract: Abstract Factors that influence fungal communities in ambrosia beetle mycangia are poorly understood. The beetle that is responsible for spreading laurel wilt in the SE USA, Xyleborus glabratus, was examined at three sites along a 500 km N-S transect in Florida, each populated by host trees in the Lauraceae. Fungal phenotypes were quantified in mycangia of individual females that were collected from a site in Miami-Dade County (MDC), 25.8oN, with swamp bay (Persea palustris), one in Highlands County (HC), 27.9oN, with silkbay (P. humulis) and swamp bay, and another in Alachua County (AC), 29.8oN, with redbay (P. borbonia). Based on combined LSU, SSU, and beta-tubulin datasets, the most prominent phenotypes were Raffaelea lauricola (cause of laurel wilt), R. subalba, R. subfusca, R. fusca, R. arxii, and an undescribed Raffaelea sp. Mean numbers of colony forming units (CFUs) of R. lauricola varied by location (p<0.003), and a multivariate analysis, which accounted for the presence and relative abundance of fungal species, indicated that there were significant variations in mycangial communities among the sites; thus, climate and vegetation may have affected fungal diversity and the relative abundance of these fungi in the mycangia of X. glabratus. Statistically, it was unlikely that any of the species influenced the presence and prevalence of another species