Evaluation of Melaleuca cajuputi Powell (Family: Myrtaceae) Extract in Aerosol Can against Dengue Vectors in the Laboratory

Abstract

Abstract

The essential oil of Melaleuca cajuputi Powell as a botanical insecticide, packaged in aerosol spray cans, was evaluated against dengue vector mosquitoes in the laboratory. Four different concentrations were used in the experiment viz: 1, 2, 5, and 10%. A total of 25 adult female Aedes aegypti were transferred into 5 cylindrical net cages and hung in a spray testing room. The aerosol cans were weighed before and after spraying. Each aerosol was sprayed for 5 and 10 seconds, respectively, and the test mosquitoes were observed for knockdown and mortality at 1, 5, 10, 15, 20, and 60 minutes. The mosquitoes were then transferred into a paper cup and fed with sugar cubes. After 24 hours, the dead mosquitoes were counted. The experiment was repeated using Ae. albopictus females. The results were then compared with the Malaysia SIRIM standard (MS standard) aerosol. High mortality, of 60.2-61.4% and 60.8-64.0%, were observed in both Aedes species when sprayed with 5% and 10% M. cajuputi aerosol, after exposure for 5 and 10 seconds, respectively. MS standard aerosol exhibited faster and higher mortality, at 97.2-97.6%. There was no significant difference (p > 0.05) between Ae. aegypti and Ae. albopictus. However, Ae. aegypti showed higher susceptibility than Ae. albopictus. The KT values for the Aedes species that had been sprayed for 10 seconds were lower than for 5 seconds. However, the SIRIM standard indicated lower KT values when sprayed for 10 seconds (KT₅₀ 0.16 min for Ae. aegypti and 2.24 min for Ae. albopictus) than essential oil (KT₅₀ 168.84 min for Ae. aegypti at 10% concentration and 123.71 min for Ae. albopictus at 10% concentration). Thus, although the MS standard aerosol (containing 0.07% prallethrin + 0.05% d-phenothrin) was more effective than canned M. cajuputi aerosol, aerosol cans containing the essential oil could be utilized for mosquito control, especially since the plant is widely available in Malaysia and elsewhere in the region.

Keywords : M. cajuputi, essential oil, aerosol can, Aedes aegypti, Ae. Albopictus