The biological control targetingthe immature stages now appears to be the most powerful means in reducing thepopulations of targeted mosquito species due to the high concern about theusage of harmful chemical insecticides. In this study, a biosurfactant producedfrom negative gram bacteria known as rhamnolipids (USM- AR2) will be usedagainst the immature stages of Aedesaegypti as a potential larvicide due to the high biodegradability and highsurface tension activity.
The larvae and pupae of Aedes aegypti will be tested on concentration range producing the LC50to LC90. During the bioassay, thebehaviour of treated larvae will be observed while the morphological featuresof the larvae also will be observed after the bioassay.The LC50 and LC90 concentrations are thenwill be used in oviposition deterrent bioassay on gravid mosquitoes to evaluatethe repellent activity of rhamnolipids as gravid mosquitoes are highlysensitive towards volatile compounds and repellent product. Even though thestudy of rhamnolipids as larvicide has been reported, the information about themechanism involved remained scarce. This study intended to reveal some of themechanism involved in the process by investigating the histopathological effectof rhamnolipids in treated larvae of Aedesaegypti.
To evaluate the potential commercial value of rhamnolipids, theresult will be compared to monomolecular surface film such as Aquatain Mosquito Formulation (AMF) and Agnique MMF inthe market. Rhamnolipids also will betested against the non-target organism such as Pomacea canaliculata (golden apple snail), Chironomuskiiensis Tokunaga (non-biting midges)and Anubias barteri (dwarf anubias). Theoutstanding properties of rhamnolipids such as degradability and low toxicity makethis environmentally friendly biosurfactant an excellent potential tool inbiological control of immature stages of Aedesaegypti in the future.