Spatial Distribution of Pasteuria nishizawae Attacking Heterodera glycines

콩씨스트선충 기생세균 Pasteuria nishizawae의 토양내 분포

Spatial distribution in soil and seasonal population changes of Pasteuria nishizawae first found in Korea from soybean cyst nematode were studied. P. nishizawae infested in 61% of areas in a soybean field; in an average, about 0.3% of 46 cysts and 17.6% of 9 juveniles per 100 g soil were infested with the bacterium. The highest percentages of spore-attached nematodes were found in July (75%) and between soil depth of 11~20 cm. The number of spores per juvenile was positively correlated with the percentage of juveniles with spores (r=0.4203; P＜0.0133), but negatively correlated with the number of juveniles in soil (r=-0.3499; P＜0.042). P. nishizawae completed its life cycle in cyst and produced 1.7$\times$105 spores per cyst.