Laboratory determination of efficacy of a Santalum spicatum extract for mosquito control

The activity of QN50, a sequiterpene alcohol derived from Australian sandalwood (Santalum spicatum), was tested for its effectiveness against larvae of 2 mosquito species (Culex molestus and Aedes camptorhynchus [Diptera: Culicidae]), nymphs of 2 species of water boatmen (Micronecta robusta and Agraptocorixa [Hemiptera: Corixidae]), immature Daphnia sp. (Crustacea), and mosquito eggs (Cx. molestus). In a series of laboratory bioassays, field-collected mosquito larvae, eggs, and immature corixids and daphnids were placed in beakers with either QN50, methoprene or source water only (control). The mosquito larvae exposed to QN50 had reduced survivorship and average longevity relative to the control and to methoprene at most concentrations used in this study. The hatching rate of mosquito eggs was unaffected by methoprene or QN50. Corixid nymphs and daphnids experienced high mortality in both methoprene and QN50 relative to the control, but there was no difference in the effect between the compounds. The results of this preliminary study suggest that further research into the mode of action and efficacy of QN50 as a potential alternative to methoprene for mosquito abatement is warranted.