Filariasis and Dengue Fever are two mosquito-borne diseases threatening French Polynesia.
The potential vectors for transmission of these illnesses are Aedes aegypti (L.), the Yellow Fever mosquito, and Ae. polynesiensis Marks. A research program financed by the Ministry of Health of French Polynesia,
the Establishment for Prevention and the Laboratory of Ecophysiology and Biotechnology
of Halophytes and Marine Algae was undertaken with the ultimate goal of development
of improved insect repellents and lures for insect traps. This goal is made more urgent
by the threat of mosquito-borne diseases. Several natural products from terrestrial
plants of French Polynesia were evaluated as spatial repellents against Ae. aegypti mosquitoes using a triple cage-dual port olfactometer and as topical repellents using
a „cloth patch assay“ test with DEET as the positive control. In addition, the attraction
of Ae. aegypti to L-lactic acid combined with the natural sample extracts were evaluated using the
dual-port olfactometer. A total of 25 plant species have been collected by the Laboratory
of Natural Products of the Institute Louis Malardé, and these have yielded 9 Essential
Oils and 21 crude methanolic extracts. The fine chemical composition of some repellent
essential oils were determined by gas chromatography and gas chromatography coupled
with Mass Spectrometry at Malardé and at Montpellier. Their major volatile components
were tested and the preliminary results are presented. Bioassays were performed with
Ae. aegypti mosquitoes at the U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS).
This mosquito is the commonly accepted standard species for laboratory bioassays.
Bioassays were conducted in with randomized sample order and distributed among the
three cages of the olfactometer over three separate assay periods per day (approximately
0800, 1100, and 1300 local time). Each sample was analyzed at least times to improve
the statistical precision of the results. The cloth patch repellency assays were conducted
using 5–6 individuals to provide adequate precision if the duration and minimum effective
dosage measures of repellent efficacy.