Surfactant‐enhanced essential oils as mosquito larvicides

Abstract

Using laboratory bioassays with fourth‐instar Culex pipiens form molestus larvae, we explored the larvicidal properties of two representative plant‐derived oils, eucalyptus oil and turpentine (two grades), and cineole, the main component of eucalyptus oil. Each was larvicidal alone, but efficacy was enhanced when the spreading pressure was increased by adding 1% insoluble surfactant (Arosurf MSF) plus 1% detergent. Cheap turpentine was more effective than more refined turpentine. These mixtures were compared with the familiar surface‐active larvicides Arosurf and Golden Bear Oil. At a dose of 2 μl per tub (=0.13 μl cm−2), enhanced by surfactants (turpentine:Arosurf:detergent 100:1:1 by volume), refined turpentine acted faster than Arosurf alone, causing higher mortality at 24 and 48 h after treatment but equivalent mortality at 72 h. It immobilised more larvae than Golden Bear Oil in the first three hours, but was less effective over 24 h. Crude turpentine enhanced by surfactants immobilised about as many larvae as Golden Bear Oil over 24 h. These findings indicate that plant essential oils merit further attention as widely available, environmentally benign mosquito larvicides.

A novel herbal formulation against dengue vector mosquitoes Aedes aegypti and Aedes albopictus

“…The abnormal and irregular movement of larvae was also observed by Choochote et al (2004) treated with Apium graveolens. Corbet et al (1995) noted the susceptibility of mosquito larvae and pupae to surface materials entering the trachea. Our results are in agreement with those reported by Chaithong et al (2006) and Islam et al (2003) against C. quinquefasciatus.…”

Biological activity of selected Lamiaceae and Zingiberaceae plant essential oils against the dengue vector Aedes aegypti L. (Diptera: Culicidae)

“…Furthermore, Tripathi et al (2002) studied that C. longa leaf oil possesses toxic, antifeedant, oviposition-deterrent and ovicidal activity against Rhyzopertha dominica F. (lesser grain borer), Sitophilus oryzae L. (rice weevil) and Tribolium castaneum Herbst (red flour beetle). The larvicidal mode of action of essential oils was investigated by Corbet et al (1995) who distinguished the susceptibility of mosquito larvae and pupae to surface materials entering their tracheal system, observing that essential oils increased the tendency to tracheal flooding and chemical toxicity. An assessment of the results presented here with the result from various other studies on the efficacy of different essential oil products is difficult.…”

Identification of chemical constituents and larvicidal activity of essential oil from Murraya exotica L. (Rutaceae) against Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus (Diptera: Culicidae)

“…In this study, the mode of action of tested materials was not studied. The larvicidal mode of action of essential oils was previously investigated by Corbet et al (1995); WHO observed that essential oils increase the tendency of tracheal flooding and chemical toxicity in mosquito larvae. Usta et al (2002) demonstrated that isolated pure compounds interfered with proton transfer in the mitochondria leading to larval mortality.…”