Detection of Hirsutella spp. and Pasteuria sp. parasitizing second-stage juveniles of Heterodera glycines in soybean fields in China

Soybean cyst nematode, Heterodera glycines, is widely distributed in soybean-producing areas, and causes great yield loss in China. The second-stage juvenile (J2) is the infective stage of the nematode; therefore reducing their numbers is important in managing this nematode. In a survey of fungal and bacterial pathogens of J2, 146 rhizosphere soil samples were taken from soybean fields distributed in 11 provinces and Beijing in China during May–August 1999. J2s native in soil plus those that remained after a 2 week incubation of soil with addition of 3000 J2s were extracted and examined for fungal and bacterial infection. Hirsutella minnesotensis was detected in 20.5% of the soil samples, Hirsutella rhossiliensis in 1.4%, and Pasteuria sp. in 26.0%. Hirsutella spp. were mainly detected in the relatively low pH soils containing more organic matter from Heilongjiang province (19.2%), whereas Pasteuria sp. was found in high pH soils with less organic matter from Anhui (10.2%), Henan (6.8%), Jiangsu (3.4%), and Shandong (2.7%). More Pasteuria sp. was detected in soils after addition of baiting nematode; detection methods had no difference in Hirsutella spp.