| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 2003: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2002: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
In order to reveal ecophysiological strategy of entomopathogenic nematodes, endotokia matricida, food source competition, and desiccation survival of the nematodes were investigated.
1.Endotokia matricia :
Infectivity of Heterorhabditis bacteriophora, Steinernema glaseri and S. carpocapse was lower for the infective juveniles (IJs) originating from endotokia matricida (E-Us) than those emerging out-of the host insects spontaneously (N-IJs). The infectivity decreased more conspicuously for the E-Us produced by the 2nd and 3rd generation adults than t hose produced by the 1st generation ones. Neri atode growth, reproduction and IJ formation were related to the density of symbiotic bacteria retained by the Us, and were higher for N-IJs than E-IJs. However, the reproduction potential of E-IJs was restored to the level similar to N-IJs. Co-culture of P. luminescens and one of nine isolates of Japanese heterorhabditids showed different compartibility among nematode-bacteria combinations. The i
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ntroduction of transposon Tn-10 to P. luininescens resulted in the formation of mutant bacteria which induced different fluorescent color appearance of host insects.
2.Competion between nematode and soil-inhabiting organisms :
Soil-inhabiting invertebrates showed different attraction to nematode-infected cadavers of Galleria mellonella larvae. Irrespective of nematode infection, two common species of ants fed on insect cadavers. However the feeding ratio was considerably different among. nematode species : ca. 5% for S. inonticolum, ca. 38% for H. indica, and ca, 70% for S. carpocapsae. The scarabeid insect hardly fed on nematode-infected insects, being indicative of emission of chemical cues from nematode-infected insects. The IJ production was disturbed by soil mesofaunae including mites, bacteriophagous nematodes and others.
3.Desiccation survival :
A new and reliable method to evaluate desiccation survival was established using a fungivorous nematode Aphelenchus avanae as a model and was applied to evaluate survivability of entomopthogenic nematodes individually. Less
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