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United States Department of Agriculture

Agricultural Research Service


Location: Bacterial Foodborne Pathogens & Mycology Research Unit

Title: Characterization and host range of the symbiotic fungus Fusarium euwallaceae sp. nov., vectored by the invasive ambrosia beetle Euwallacea sp.

item Freeman, S -
item Sharon, M -
item Maymon, M -
item Mendel, Z -
item Protasov, A -
item Aoki, T -
item O Donnell, Kerry

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 24, 2013
Publication Date: N/A

Technical Abstract: A novel symbiotic Fusarium euwallaceae fungus that serves as a specific nutritional source for the invasive Asian ambrosia beetle Euwallacea sp. (Coleoptera, Scolytinae, Xyleborini) is farmed in the galleries of host plants. This beetle-fungus complex, which has invaded Israel and California, is closely related to the tea shot-hole borer (E. fornicatus) and its obligate symbiont, F. ambrosium, occurring in Sri Lanka and India. Both fusaria produce clavate macroconidia, they exhibit distinctive ecologies and comprise a genealogically exclusive lineage within Clade 3 of the Fusarium solani species complex (FSSC) that can be differentiated using arbitrarily-primed PCR. The beetle-fungus complex poses a serious threat to avocado (Persea americana) production in Israel and causes damage to several other tree species, including oak (Quercus spp.). The fungal symbiont, which is maintained within paired mandibular mycangia, is transported within and from the natal galleries by adult female beetles. Damage caused to the xylem is associated with disease symptoms that include sugar exudates, dieback, wilt and finally host tree mortality due to the fungus. Certain tree species such as persimmon allow initial penetration of the bark, however, the fungus does not manage to colonize the xylem; therefore disease does not develop. However, sawdust and xylem tissue of persimmon incorporated into the growth medium allowed the fungus to proliferate, which in turn provided nutrition that allowed the beetle to complete its lifecycle in vitro. Specificity of the fungus/beetle development in vitro vs. in vivo culturing conditions will be discussed.

Last Modified: 4/24/2014
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