Adulticidal effect of seven terpenes and a binary combination against Aedes aegypti

Abstract

While many studies have explored the effect of essential oils on larvae of diverse culicid species, there are few works about the effect of pure terpenes on Ae. aegypti adults. The current study examines the effects of lethal exposure to seven different terpenes (eucalyptol, limonene, pulegone, γ-terpinene, citronellal, linalool and β-caryophyllene) by Ae. Aegypti adults and aims to detect possible synergistic effects by combining the most active ones. All evaluated terpenes strongly affected Ae. aegypti survival, although with considerably differences between them. Out of the seven terpenes, pulegone and citronellal were the most effective with LC50 values lower than 0.1 mg/L. No significant differences were registered between both compounds. Pulegone and citronellal were chosen for the binary combination fumigation assay based on their high activity. Calculated LC25 was 0.015 and 0.012 mg/L for each terpene, respectively. These concentrations were used for the binary combination assay. The observed response for the combination resulted 1.8.times higher than expected (Table 2). The χ2 calculated coefficient value was higher than 3.84, indicating that the effect of combined terpenes is synergistic at the (1:1) tested relation