A preliminary study on mosquito larvicidal efficacy of rotenone extracted from Malaysia Derris sp

Abstract

Rotenone is a bio-active compound extracted from Derris elliptica (locally known as ‘Tuba’ plant). It has long been used as bio-pesticide, which is more environmental friendly than the commercially available pesticides and has the potential to be used in eliminating mosquito larvae. Therefore, the objective of this study is to determine the mosquito larvicidal activity (LC50) through the usage of liquid crude extract of Derris plant root. The rotenone liquid crude extract was extracted using normal soaking extraction (NSE) method. Two different solvent ratios were used to extract rotenone namely: (A) methyl chloride: methanol (1:1) and (B) methyl chloride: methanol (1:9). The extracts were concentrated using rotary evaporator at 40 °C with vacuum pressure of 800 mbar prior to the reverse-phase high performance liquid chromatography analysis (RP-HPLC) and biological activity (LC50) study. Next, the diluted extracts were subjected to the biological activity treatment for 6 hrs. The results showed that the concentrated liquid crude extracts of methyl chloride: methanol (1:1) which contained the highest rotenone content produced the lowest treatment concentration of 0.024 mg/ml to achieve 50% mortality within 3 hrs of treatment (p<0.05). The rapid mortality (as indicated by the LC50 value) of the mosquitoes’ larvae against rotenone extracted from Derris plant roots has proven that it has the potential to be used as larvicide to control vector-borne diseases especially from mosquitoes.