|HEWLETT, THOMAS - Pasteuria Bioscience|
Submitted to: Society of Nematologists Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/21/2009
Publication Date: N/A
Technical Abstract: Spores of Pasteuria nishizawae were first recovered in Tennessee in 2008 attached to soybean cyst nematode juveniles, Heterodera glycines, and inside cysts extracted from soil collected at Ames Plantation, Grand Junction, TN. The field had a 15% increase from 1997 through 2004 in number of samples where soybean cyst nematode was not detected, even in the presence of favorable conditions and susceptible cultivars. There was a 16% decrease in soybean cyst nematode population density in greenhouse bioassays of collected soil samples from 2001 through 2004. Fifty percent of the original samples examined contained parasitized juveniles or cysts. Preliminary studies of levels of infestation in Tennessee soybean production fields indicated 78% of the soil samples with greater than 5 cysts per 100 cm3 of soil were infested with P. nishizawae. Cyst and juvenile infestation levels within the samples were highly variable. Studies were initiated to increase the spore level of P. nishizawae in greenhouse cultures containing soybean cysts. Cysts free of eggs, as well as abnormally developed eggs within cysts, were present after 35 days. Seven populations of soybean cyst nematode corresponding to HG Types 126.96.36.199.5.6.7 (2 populations), 5.7 (2 populations), 2.5.7, 188.8.131.52, 184.108.40.206 (races 1, 2, 3, 5, 14, and 2 populations which reproduce on all indicator lines) were exposed to 100,000 spores of P. nishizawae, respectively. The average number of spores per vermiform ranged from 0.8 to 4.5. Fifty to 100% of the vermiform stages had at least one spore. No differences in spore attachment were found between the various HG Types. Spores were detected on males; however, no spore attachment was observed on dead juveniles. Calibration curves were developed from 10,000 to 1,000,000 spores per mL to determine the level of spore addition needed for consistent detection of P. nishizawae.