Abstract
Malaria is endemic to Lombok Island, Indonesia. One approach to suppress malaria spread is to eliminate anopheline larvae in their habitat and the environmentally safe agent is bacteria, that is, Bacillus sphaericus. However, there is no information regarding local isolate of B. sphaericus that is toxic to mosquito larvae from Lombok. The aims of the study were to isolate B. sphaericus from soil in areas close to beach surrounding Lombok Island and to test their toxicity against 3rd instar Anopheles aconitus larvae. Soil samples were collected from 20 different sampling locations from Lombok Island and homogenized with sterile physiological salt solution. Suspension was heat-shocked at 80°C for 30 minutes and then spread onto antibiotic-supplemented NYSM solid medium. Colonies grown were characterized and subjected to initial toxicity test against anopheline larvae. Isolates with more than 50% killing percentage were subjected to bioassay testing against anopheline larvae. From 20 locations, 1 isolate showed mild toxicity (namely, isolate MNT) and 2 isolates showed high toxicity (namely, isolates SLG and TJL2) against An. aconitus. Those 3 isolates were potentially useful isolates, as they killed almost all larvae in 24 hours. The discovery of toxic indigenous isolates of B. sphaericus from Lombok Island opens opportunity to develop a biopesticide from local resources.
Highlights
Lombok Island is one island in West Nusa Tenggara Province of Indonesia
Morphology characteristics of B. sphaericus isolated from Lombok Island are presented in Figure 2 and their characteristics are presented on Table 1
The characteristics of putative B. sphaericus isolates were in agreement with standard characteristics mentioned in Bergey’s Manual of Determinative Bacteriology [7]
Summary
Lombok Island is one island in West Nusa Tenggara Province of Indonesia. One of common infectious diseases on Lombok is malaria. It is predicted that at minimum 13,000 people are suffering from the disease [1]. Malaria is caused by a protozoa called Plasmodium and spreads among humans by bites from anopheline mosquitoes. One species that has been identified as a malarial vector on Lombok is Anopheles aconitus. The species lives at locations ranging from sea level to 600–800 m above sea level. The larvae of An. aconitus can be found on rice fields (planted and unplanted), various shallow pools (rock, stream, and flood), and slow moving streams with grassy margins [2]
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