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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Mycotoxin Prevention and Applied Microbiology Research » Research » Publications at this Location » Publication #325122

Title: Evolution of the Fusarium–Euwallacea ambrosia beetle mutualism

Author
item O Donnell, Kerry

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/30/2016
Publication Date: 9/30/2016
Citation: O'Donnell, K. 2016. Evolution of the Fusarium–Euwallacea ambrosia beetle mutualism [abstract].

Interpretive Summary:

Technical Abstract: The Euwallacea – Fusarium mutualistic symbiosis represents one of the independent evolutionary origins of fungus-farming. Diversification time estimates place the evolutionary origin of this mutualism in the early Miocene approximately 21 million years ago. Fusarium is best known as one of the most important mycotoxigenic plant pathogens. The genus comprises over 300 phylogenetically distinct species distributed among 22 monophyletic species complexes. The lineage of fusaria cultivated by Euwallacea as a source of food, termed the Fusarium Ambrosia Clade (AFC), is nested within the F. solani species complex. Because the highly inbred haplo-diploid Euwallacea ambrosia beetles and the fusaria that they farm are notoriously cryptic morphologically, species limits within both groups were inferred using genealogical concordance phylogenetic species recognition employing multilocus DNA sequence data. These analyses identified 12 AFC species, but only two have been described formally. Nine AFC species are cultivated by seven different Euwallacea spp. The Fusarium-farming Euwallacea clade comprises eight phylogenetically distinct species, six of which represent cryptic species lineages within the morphospecies E. fornicatus. These exotic pests pose a significant threat to avocado production worldwide because at least four of the six phylogenetic species within the E. fornicatus Clade can use it as a reproductive host. Lines of evidence that indicate the Euwallacea – Fusarium mutualism has been driven by host-shift speciation include two of the seven Euwallacea spp. analyzed cultivate two closely related AFC species and cophylogenetic analyses suggest that Euwallacea spp. have switched fusarial symbionts at least five times over the evolutionary history of this mutualism.