The preliminary studies on culture of the entomopathogenic nematode, Steinernema abbasi, using a liquid medium

• Main Authors: Ying-Hsiang Liu, 劉穎祥
• Other Authors: 唐立正
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/78935999535361180042

碩士 === 國立中興大學 === 昆蟲學系所 === 99 === Using a liquid medium to culture the entomopathogenic nematode, Steinernema abbasi, was carried out in shaker flasks. This culture medium and method could support both S. abbasi and Steinernema carpocapsae All growth and reproduction, after culturing for 14 days, the yields of infective juveniles (IJs) were 3.0 × and 6.7 × 104 IJs/ml, respectively. When the rotation speed was set up at 70 and 110 rpm, the IJ yields using cell culture flasks were 3.4 × and 4.5 × 104 IJs/ml with statistically significant difference. When cultured in Erlenmeyer flask with rotation speed at 70 and 110 rpm, the yields were 1.3 × and 1.2 × 104 IJs/ml, respectively. However, when rotation speed was set up at 150 rpm and cultured in cell culture flask or Erlenmeyer flask, the nematode yields were less than the initial IJs numbers. While increasing inoculum sizes from 5 to 5,000 IJs/ml, the yields between four treatments were not significantly different after culturing for 14 days. It seems that the culturing conditions in the medium were not suitable for nematodes to grow well. The culture medium without sucrose could support nematode growth, the yields being 7,425 IJs/ml. Increase in the sucrose concentration in culture media from Brix 5.2 to 20.8% resulted in the nematode yields to be from 3.1 to 5.4 × 104 IJs/ml, whereas the yields decreased to 4.2 × 104 IJs/ml at Brix 26%. When inoculated with 500 IJs/ml and cultured for 18 days, the emergence of IJs started to increase at the 6th day, and reached the maximum yields at 10th day after culturing. Using one-on-one bioassay, the mortalities of 5th instar larva of Spodoptera litura treated with in vivo- and in vitro-cultured S. abbasi were not significantly different, and the LT50 values were 105.97 and 103.97 h, respectively. When applied 5, 10 and 30 IJs to each 5th instar larva of S. litura, the virulence caused by different dosages was significantly different, but at the same dosage the virulence between in vivo and in vitro cultures was not significantly different. This result showed that nematodes cultured in a liquid medium exhibited similar pathogenicity as those cultured in vivo.