Fumigant Insecticidal Activity and Repellent Effect of Five Essential Oils and Seven Monoterpenes on First-Instar Nymphs of Rhodnius prolixus

• Published in: Journal of medical entomology Vol. 46; no. 3; pp. 511 - 515
• Main Authors: Sfara, V, Zerba, E.N, Alzogaray, Raúl A
• Format: Journal Article
• Language: English
• Published: England 01.05.2009
• Subjects: Animals; botanical insecticides; chemical concentration; essential oils; fumigant insecticides; Fumigation; insect control; Insect Control - methods; insect repellents; Insecticides; instars; knockdown time; Monoterpenes; monoterpenoids; Nymph; nymphs; Oils, Volatile; Plant Oils; Plants - chemistry; repellency; Rhodnius - growth & development; Rhodnius prolixus; toxicity; vapors
• ISSN: 0022-2585; 1938-2928
• DOI: 10.1603/033.046.0315

The aim of this study was to evaluate the fumigant and repellent activity of five essential oils (from eucalyptus, geranium, lavender, mint, and orange oil) and seven monoterpenes (eucalyptol, geraniol, limonene, linalool, menthone, linalyl acetate, and menthyl acetate) on first-instar nymphs of the bloodsucking bug Rhodnius prolixus Stahl (vector of Chagas disease in several Latin American countries). Fumigant activity was evaluated by exposing the nymphs to the vapors emitted by 100 xl of essential oil or monoterpene in a closed recipient. The knockdown time 50% (KT50) for eucalyptus essential oil was 215.6 min (seven times less toxic than dichlorvos, a volatile organophosphorus insecticide used as a positive control). The remaining essential oils showed a poor fumigant activity: <50% of nymphs were knocked down after 540 min of exposure. The KT50 values for monoterpenes, expressed in minutes, were as follows: 117.2 (eucalyptol), 408.7 (linalool), 474.0 (menthone), and 484.2 (limonene). Eucalyptol was 3.5 times less toxic than dichlorvos. No affected nymphs were observed after 540 min of exposure to geraniol, linalyl acetate, or menthyl acetate. Repellency was quantified using a video tracking system. Two concentrations of essential oils or monoterpenes were studied (40 and 400 xg/cm2). Only mint and lavender essential oils produced a light repellent effect at 400 xg/cm2. Geraniol and menthyl acetate produced a repellent effect at both tested concentrations and menthone only elicited an effect at 400 xg/cm2. In all cases, the repellent effect was lesser than that produced by the broad-spectrum insect repellent N,N-diethyl-3-methylbenzamide (DEET).