Pengasingan, saringan dan pengecaman agen mikrobial tempatan untuk mengawal nyamuk yang penting dari segi kesihatan awam di Malaysia

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dc.contributor.authorHan Lim, Lee
dc.date.accessioned2015-07-30T04:39:01Z
dc.date.available2015-07-30T04:39:01Z
dc.date.issued1995
dc.description.abstractMosquito-borne diseases are today still important tropical diseases causing significant morbidity and mortality. Prompted by problems of chemical control of mosquitoes, renewed interest in biological control especially the microbial control agents has been revived. The major objective of the present undertaking is to isolate and identify '9Tomising Malaysian isolates of bqcterial control agents of mosquito and to examine their role in vector control. Field collection of soil and water samples from ecologically diversified potential mosquito breeding habi- ·tats in Malaysia for the purpose of isolating potential microbial control agents was conducted. To date, a total of 876 soil & water samples and dead insects were collected and from these samples, 3 922 bacterial colonies were obtained after culturing on different types of media. These microbial agents were completely screened for their larvicidal activity against Aedes aegypti and Culex quinquefasciatus. From such screenings, a total of 29 Bacillus thuringiensis isolates were obtained which included 25 isolates of serotype H-14, 1 isolate each of serotype H-7, H-8a8b, an isolate related to H-28 and an untypable isolate tentatively named as subsp malaysianensis (for identification purpose). In addi~ion, 8 isolates of B. sphaericus were also obtained. These included 4 isolates each of serotype H-5a5b and H-25. Of special interest is an isolate of B. sphaericus H5a5b which also exhibits antimicrobial characteristics in addition to its mosquitocidal activity. Other larvicidal microbial agents isolated were· a new anaerobic Clostridium bifermentans serovar malaysia and 2 isolates of Pseudomonas pseudornallei. All these bacterial agents exhibited high activity against mosquito larvae. Field evaluation of an isolate of B. thuringiensis H-14 (IMR-BT-8) and B. sphaericus (IMR-BS-4) was conducted against ·'-A.{J. karwari. At 1.8 kg/ha, IMR-BT-8 was effective for 5 days, whilst IMR-BS-4 was effective for 11 days at 0.8 kg/ha. In trial against Cx. pseudovishnui, IMR-BT-8 drastically reduced the larval population 24 and 48 h postspraying. However, the effect of IMR-BT-8 on Mansonia at 2.5 kg/ha in a limited field trial was inconclusive. At 2.0 mg/1, IMR-BT-20 was effective for more than 3 weeks against Ae. albopictus breeding in earthen jars and about 20 days in tyres at 1.0 mg/1. IMR-BT-8 was less effective in similar habitat. In summary, this screening programme has been highly successful. Similar techniques could therefore be expected to be applicable in other tropical regions.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/1012
dc.language.isootheren_US
dc.subjectAgen mikrobialen_US
dc.subjectMengawal nyamuken_US
dc.subjectKesihatan awamen_US
dc.titlePengasingan, saringan dan pengecaman agen mikrobial tempatan untuk mengawal nyamuk yang penting dari segi kesihatan awam di Malaysiaen_US
dc.typeThesisen_US
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