Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/1998
Publication Date: N/A
Interpretive Summary: Phytosanitary surveys of grass and grain seeds for the presence of wheat Karnal bunt (TILLTETIA INDICA) spores have recently found a number of morphologically similar spores here proven to be those of the fungus NEOZYGITES PARVISPORA, a pathogen of thrips occurring on grass and cereal grain plants. The morphology of these thick-walled (zygo)spores and, for the first time, their mode of germination are demonstrated. This is the first reports of N. PARVISPORA from the US (Oregon, Arizona and Tennessee) and from New Zealand; all previous reports of this fungus are from European thrips. This report may help to prevent misidentifying a beneficial fungus (the thrips pathogen) as a damaging plant pathogen (Karnal bunt) whose detection in any quantity in seed lots can have very undesirable economic and political consequences. This report is useful for mycologists, entomologists, invertebrate pathologists, and is especially significant for plant quarantine inspectors and regulators.
Technical Abstract: Resting spores of NEOZYGITES PARVISPORA, an obligate pathogen of thrips, were found in washes from seed of cultivated annual ryegrass (LOLIUM MULTIFLORUM) from Oregon. Similar spores were found in washed from seed samples of annual ryegrass from Tennessee, wheat from Arizona and wild tall fescue (GESTUCA ARUNDINACEA) from New Zealand. In the Oregon specimens, the resting spores were formed inside the bodies of thrips 9LIMOTHRIPS sp.) wedged between the palea and seed in ryegrass. The resting spores germinated directly to produce a germ conidium on a short conidiophore. This is the first report of resting spore germination in N. PARVISPORA, and the first report of the species outside of Europe.