Identifier

etd-04042013-104148

Degree

Master of Science (MS)

Department

Plant Pathology and Crop Physiology

Document Type

Thesis

Abstract

There are more than 7800 species of Pucciniales (rust fungi) described. Aeciospores and urediniospores of rust fungi are a food source for the larval stage of members of the fly genus Mycodiplosis, hence these could be of interest as potential biological control agents. Currently, Mycodiplosis contains 49 described species based on adult male morphology. A survey of 1,350 rust-infected plants from 44 countries was recently conducted to assess the occurrence of Mycodiplosis fly larvae across a broad spectrum of Pucciniales. Larvae were found on 261 collections from 25 countries. Statistical analyses explored the distribution of larvae in relation to host species. Five of 127 rust species in the survey data were identified as infested at a greater frequency than expected using binomial probability analysis of presence/absence. DNA was extracted from individual larvae and 28S nuclear ribosomal RNA and mitochondrial cytochrome c oxidase subunit 1 (COI) genes were amplified and sequences were concatenated for maximum likelihood analyses. Test analyses were done using identical sequence regions of 28S and COI from Bradysia species and Asteromyia species respectively, to verify the ability of individual loci to resolve species. The 206 larval specimens analyzed were resolved into approximately 33 clades, 17 of which received significant support. One clade has a global distribution in the survey. Twelve clades occurred in the United States. There are currently seven species described from the United States, the finding of 12 clades in this study represents potential additional species in the Mycodiplosis. The distribution of larvae within clades could be explained partially by geographic origin but not by rust host at any taxonomic level; thus even though there is evidence for preferential feeding by larvae on some rust species, there is no evidence of host-specificity between clades of larvae and their hosts.

Date

2013

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Aime, Mary Catherine

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