Effect of Harvest Time and Infective Juvenile Size of the Entomopathogenic Nematode, Steinernema arenarium, on Pathogenicity, Development, and Propagation

Abstract

The size of infective Steinernema arenarium juveniles is variable and ranges from 724 to 1408 ㎛. Effects of harvest time and infective juvenile size on pathogenicity, development, and reproduction were examined in the last instar of the great wax moth, Galleria mellonella. Harvest time of infective juveniles (IJs) of S. arenarium affected pathogenicity. IJs harvested at the 10th day from trapping were more pathogenic than those harvested the 3rd day from trapping. Mortality of G. mellonella also depending on harvest time, i.e, 100% died within 48h when IJs were harvested at the 10th day, without relation to size. However, mortality was 40% in the small size group (SSG) compared with 18% in the large size group (LSG) within 48h when IJs were harvested at the 3rd day. Establishment of S. arenarium within the host was different depending on IJ size. The number of established IJs was 1.8 in the SSG, 3.3 in the LSG, and 3.2 in the mixed size group (MSG) when IJs were harvested at the 3rd day, and 5.3 in the SSG, 7.4 in the LSG, and 7.6 in the MSG when IJs were harvested at the 10th day. The length of the female adult was 7,070.5 ㎛ in the SSG and 7,893.9 ㎛ in the LSG and that of the male was 1,460.5 ㎛ in the SSG and 1,688.2 ㎛ in the LSG when IJs were harvested at the 3rd day. The length of the female adult was 7,573.6 ㎛ in the SSG and 8,305.4 ㎛ in the LSG and that of the male adult was 1,733.4 ㎛ in the SSG and 1,794.4 ㎛ in the LSG when IJs were harvested at the 10th day. Harvest time and size of IJs did not influence numbers of progeny or size of IJS.

Evaluation of Entomopathogenic Nematodes against Armyworm, Pseudaletia separata on Tall Fescue, Festuca arundinacea

“…적용 농도의 ¼농도부터 4배 농도까지 통계적 유의성이 없이 높은 병원성을 나타내어 이러한 요인도 멸강나방이 곤충병원성선충에 대해 감수성이 높기 때문으로 생각된다. 곤충병원성선충의 종이나 계통, 기주의 종류와 발육단 계는 곤충병원성선충의 병원성에 영향을 미치는 주요 인 자들이며 이들은 기주의 면역반응이나 곤충병원성선충 공 생세균의 독성과 관련이 있다 (Dowds and Peters, 2001;Han et al, 2012 (Lee et al, 2006a(Lee et al, , 2010. S. carpocapsae GSN1 strain의 경우 30 o C까 지는 병원성이 높아지나 35 o C에서는 감소하였다 .…”