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Poster: Diseases of Plants: New & Emerging Diseases


Fungi in the wood: The fungi associated with the ambrosia beetle, Xylosandrus germanus and its galleries in Malus domestica
S. VILLANI (1), K. Ayer (2), D. Breth (3), K. Cox (2) (1) North Carolina State University, U.S.A.; (2) Cornell University, U.S.A.; (3) Cornell Cooperative Extension, U.S.A.

The ambrosia beetle, Xylosandrus germanus, is considered an emerging threat to Western New York apple orchards. There are concerns that fungal farms established by X. germanus within vascular tissue play a role in the collapse of young apple trees. To gain further insight into the identity and relationship between fungi associated with X. germanus and decline of Malus x domestica, fungal isolations were performed from X. germanus wood galleries and adjacent vascular tissue, and beetles recovered from galleries. Fungal identity was confirmed by sequencing the 2 internal transcribed spacer regions and the 5.8S gene of ribosomal DNA. Five distinct fungal species were recovered from the exterior of 36 beetles, while only 2 fungal species were recovered from the beetles’ interior. Nectria haematococca (an. Fusarium solani) was most frequently isolated from the exterior and interior of X. germanus, while Ambrosiella xylebori, another common food source of ambrosia beetles, was only isolated from the interior and exterior of one beetle. Interestingly, however, A. xylebori was predominantly recovered from infested wood tissue. Our results suggest that X. germanus can establish fungal gardens of N. haematococca and A. xylebori within vascular tissue of apple trees, however it is unclear if tree decline is likely due to direct tunneling or colonization of A. xylebori. Additional investigations are ongoing to understand the implications of A. xylebori colonization of apple.