Geographic variation in the mycangial mycoflora of Xyleborus glabratus in Florida
A. S. CAMPBELL (1), R. C. Ploetz (1), P. E. Kendra (2), W. S. Montgomery (2). (1) University of Florida, Homestead, FL, U.S.A.; (2) Subtropical Horticulture Research Station, USDA-ARS, Miami, FL, U.S.A.
Laurel wilt kills <i>Persea borbonia</i> and other American members of the Lauraceae. It is caused by <i>Raffaelea lauricola</i>, a fungal symbiont of an exotic ambrosia beetle, <i>Xyleborus glabratus</i>. <i>R. lauricola</i> and other fungi were quantified in <i>X. glabratrus</i> collected from three locations in Florida. A Miami-Dade Co. (MDC) site, 25.8<i>º</i>N, was populated by <i>P. palustris</i>, a Highlands Co. (HC) site, 27.9<i>º</i>N, by <i>P. borbonia,</i> <i>P. humulis</i> and <i>P. palustris</i>, and an Alachua Co. (AC) site, 29.8<i>º</i>N, by <i>P. borbonia.</i> Mycangia from individual females were macerated and plated on CSMA and ½ PDA. Seven putative taxa were identified based on identical LSU genotypes and colony phenotypes. With the exception of <i>R. lauricola</i> and <i>Zygozyma oligophaga</i>, it was not possible to match LSU genotypes/sequences with those deposited in GenBank, as the remaining taxa were 98 to 99% similar to two or more species of <i>Fragosphaeria</i>, <i>Leptographium</i>, <i>Grosmannia</i> and/or <i>Ophiostoma</i>. The numbers of <i>R. lauricola</i> colony forming units (CFUs) in <i>X. glabratrus</i> varied by location (p<0.0003), as beetles from MDC had more CFUs (3,532) than those from HC (2,593) and AC (1,829). The numbers of fungal species also differed by location (p<.0001), as 80% of the individuals from AC and MDC carried ≥3 species, compared to 31% of those from HC. The results indicate that climate and vegetation may affect fungal diversity and the relative abundance of <i>R. lauricola</i> in the mycangia of <i>X. glabratus</i>.
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