Joseph Pagaya, - (2000) Isolasi Bacillus thuringiensis Dari Tanah Dan Uji Toksisitasnya Terhadap Larva Nyamuk Aedes aegypti Linn. Dan Spodoptera litura Fab.: Penelitian Eksperimental Laboratorik. Thesis thesis, UNIVERSITAS AIRLANGGA.

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Abstract

Bacillus thuringiensis is one of the most developed microorganism against both pests and diseases insects vector. Toxicity is due to the presence of certain crystal protein 8-endotoxin, inside the bacterium. The toxicity is more specific for insect and is safe for the environment, humans and mammals and insects do not develop resistency. The objective of this research is to study the toxicity of the crystal protein and endospores form soil bacillus isolated, against Spodoptera litura Fab. larva and the Aedes agypti Linn. mosquito's larva. Sample of soils were collected from six ecology system which included forest, rice field, foot hill, pond, mangrove swamp and plantation in Morotai island. On the spot, about 100 gram of the soil was collected using sterile plastic spoons, placed in sterile plastic bags. In the laboratory, about 1 gram of soil sample was weighted for the isolation of endospore form bacilli. Chilcott and Wigley's method was used for the identification of B.thuringiensis. The positive isolates of B.thuringiensis were measured for potency of toxicity with insect larva mortality as observation unit. A personal computer programmed with probit analysis was used to analyze data. ANOVA one-way was used to the hypothesis test, continued by multiple comparison test with LSD method at a= 0,05 significant level. A total of 409 bacterial colonies were isolated, 21 positive B.thuringiensis isolates were found. From such bioassay, 4 isolates were toxic to the Ae.aegypti larva those were MRT-8.02, MRT-8.03, MRT-8.04 and MRT-C.02. Six isolates were toxic to the S.litura larva those were MRT-C.04, MRT- 0.01, MRT-0.02, MRT-E.03, MRT-E.04 and MRT-F.01 . Data obtained by probit analysis showed that each MRT- 8.04 and MRT-E.03 isolates were more toxic to Ae.aegypti and S.litura larva, because it has a lower LC50 and LC90 values than the other isolates collected. The ANOVA showed, that the toxicity differed significantly between the isolates collected from soils both to Ae.aegypti and S./itura, so that null hypothesis was rejected.

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