Geographic variation in mycangial communities of Xyleborus glabratus

Abstract

Factors that influence fungal communities in ambrosia beetle mycangia are poorly understood. The beetle that is responsible for spreading laurel wilt in SE USA, Xyleborus glabratrus, 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), 25.8N, with swamp bay (Persea palustris), one in Highlands County (HC), 27.9N, with silkbay (P. humulis) and swamp bay and another in Alachua County (AC), 29.8N, 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 might 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.

• ambrosia beetle
• avocado
• laurel wilt
• mycangia
• Raffaelea lauricola
• symbiont
• Xyleborus glabratus

Acknowledgments

This research was financed partially by USDA NIFA grant 2009-51181-05915. We thank Dr James Colee (UF-IFAS-Statistics Department) for help with the statistical analysis. Thanks also to Josh Konkol, Jill Ploetz and Ronald Wideman for their help with finding and processing the beetles.