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Title: Mycodiplosis infestation of rust fungi is frequent, wide spread, and possibly host specific

Author
item Henk, Daniel
item Farr, David
item Aime, Mary

Submitted to: Fungal Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2011
Publication Date: 6/19/2011
Citation: Henk, D.A., Farr, D.F., Aime, M.C. 2011. Mycodiplosis infestation of rust fungi is frequent, wide spread, and possibly host specific. Fungal Ecology. 4:284-289.

Interpretive Summary: Rust fungi are a very large and diverse group of parasites that attack plants and each year cause billions of dollars crop loss in the United States and throughout the world. Many aspects of the basic biology of rust fungi are still unknown. Rust spores are generally thought to be distributed by the wind, yet we have observed that insect larvae commonly feed on rust spores and thus may effect the distribution of rust spores. These insect larvae are fungus-feeding gall flies. To determine the extent of their occurrence, over 500 collections of rust fungi were examined. Approximately 20% of these collections were infected with the insect larvae. This frequency suggests that the larvae can have an impact on the distribution of the rust fungi. Knowledge of the distribution of these fungi is useful to agronomists and plant pathologists who are working to control these destructive plant pathogens.

Technical Abstract: Larvae of some Mycodiplosis species (Insecta, Diptera) feed primarily on spores of rust fungi (Basidiomycota, Pucciniales). The number of rust-feeding species and their relative frequency, distribution, and degree of host-specificity are not known. A survey of 200 recent rust collections from around the world, and a systematic survey of 333 herbarium specimens from Maryland show that Mycodiplosis infestation is very common. Desiccated larvae were found on specimens dating back as far as 1886, the oldest collection in the survey. Greater than 20% of all rust collections examined were infested with Mycodiplosis larvae. In Maryland infestation frequencies were similar at different spatial scales, but different rust species varied in their frequency of infestation. Primers were designed to target Mycodiplosis 28S rDNA, and sequence data reveal genetic variation between Mycodiplosis isolates from different rust species and different geographic locations.