The growth inhibition activity and sublethal effects (EI50) of the crude extract of Cyperus aromaticus Mattf and Kukenth (Cyperaceae), containing juvenile hormone III (JH III) was evaluated against the 3rd instar larvae of two Aedes mosquito species, namely Aedes aegypti (Linnaeus) and Aedes albopictus Skuse under laboratory conditions. A steam distillation system was used to prepare the crude extract from whole parts of natural plant which collected from different parts of Penang, Malaysia. The crude extract was analyzed by High-Performance Liquid Chromatography (HPLC). Laboratory evaluation was carried out against late 3rd instar larvae of the Vector Control Research Unit (VCRU) strains of Ae. aegypti and Ae. albopictus using the standard WHO method. Bioassay tests presented the remarkable growth inhibition activity of the extract of C. aromaticus against the two test Aedes mosquitoes. Ae.albopictus was significantly more susceptible to the crude extract with the lower EI50 value of 30.37 µg/ml, followed by Ae. aegypti with EI50 values of 39.52 µg/ml. The reproductive potential, growth period, adult size and longevity of the mosquitoes were significantly affected following exposure to sublethal dosage (EI50) of the extract, but the sex ratio of the adult population was not significantly affected . The present study revealed the bioefficacy of the crude extract of C. aromaticus (Whole plant) in controlling Aedes mosquito populations in the effort to reduce the transmission of dengue fever.
