Behavioral and Toxicological Responses ofRhodnius prolixusandTriatoma infestans(Hemiptera: Reduviidae) to 10 Monoterpene Alcohols

Abstract

The effect on locomotor activity, the repellency, and the knock-down produced by 10 monoterpene alcohols were evaluated on first-instar nymphs of Rhodnius prolixus and Triatoma infestans, vectors of Chagas disease. A video tracking technique was used to evaluate locomotor activity and repellency by exposure to papers impregnated with monoterpenes. Eugenol on R. prolixus and (S)-cis-verbenol on T. infestans did not modify the locomotor activity. The remaining monoterpenes produced hyperactivity on both species, although the concentration required was at least a 1,000 times higher than that of deltamethrin (positive control). Carvacrol, eugenol, and geraniol resulted as repellent as N,N-diethyl-m-toluamide (positive control) for both species. A similar result was observed for almost every monoterpene on T. infestans. Knock-down effect was evaluated by exposing the nymphs in closed recipients. The order of increasing toxicity on R. prolixus was (KT50 values in min): geraniol (213.7) < alpha-terpineol (164.5) < linalool (124.2) < carvacrol (111.6) < eugenol (89.8) < thymol (78.9), and on T. infestans: alpha-terpineol (289.8) < eugenol (221.3) < carvacrol (164.2) < linalool (154.9) < thymol (96.7). All monoterpenes were less toxic than the positive control, dichlorvos (3.6 min for R. prolixus and 3.9 min for T. infestans). After 7 h of exposure, (-)-carveol, citronellol, and menthol (on both species) and geraniol (on T. infestans) produced < 50% of knock-down. After these results, it is worthwhile to explore more deeply the potential of these compounds as tools for controlling Chagas disease vectors.

Lethal and sublethal effects of essential oil of Lippia sidoides (Verbenaceae) and monoterpenes on Chagas’ disease vector Rhodnius prolixus

“…High toxicity levels of carvacrol in comparison to thymol was also verified by Moretti et al (2013), who evaluated the knock-down effect of these monoterpenes on nymphs of T. infestans first stage and R. prolixus. Although the structures of these phenolic compounds are similar, with the same chemical formula and molecular weight, they differ in the position of the hydroxyl group on the aromatic ring, so they are classified as position isomers (Fig.…”

“…The monoterpene thymol, EOLS major component (69,91%), presents high levels of toxicity against several insects (Pavela 2011). In triatomines, recent studies described that the treatment of Triatoma infestans and R. prolixus with thymol caused hyperactivity and knock-down effects in first nymphs while the repellency effect was observed only in T. infestans nymphs (Moretti et al 2013). …”

“…The higher insecticide activity of thymol in comparison to carvacrol is widely described in the literature (Singh et al 2009). In triatomines, the exposure of R. prolixus and T. infestans nymphs to carvacrol causes an increase in locomotor activity, repellency and knock-down effect (Moretti et al 2013). …”

Toxicity, repellency and flushing out in Triatoma infestans (Hemiptera: Reduviidae) exposed to the repellents DEET and IR3535

“…Pyrethroids and some botanical monoterpenes induce a non-directional increase in the locomotor activity of insects (Gammon, 1978; Alzogaray, Fontán & Zerba, 1997; Moretti, Zerba & Alzogaray, 2013). If the exposed insects are hidden in a shelter, they leave it by chance.…”

Insecticidal action of synthetic girgensohnine analogues and essential oils on Rhodnius prolixus (Hemiptera: Reduviidae)

“…It is urgent to find natural active ingredients or new alkaloid-like molecules to replace these insecticides (14,15), as their constant use has generated resistance mechanisms in some Triatomine species of epidemiological importance (2). Among these new molecules, synthetic analogues of the girgensohnine alkaloid structure were designed and synthesized to inhibit the activity of acetylcholinesterase (AChE).…”