Comparison of the Insecticidal Characteristics of Commercially Available Plant Essential Oils AgainstAedes aegyptiandAnopheles gambiae(Diptera: Culicidae)

Abstract

Aedes aegypti and Anopheles gambiae are two mosquito species that represent significant threats to global public health as vectors of Dengue virus and malaria parasites, respectively. Although mosquito populations have been effectively controlled through the use of synthetic insecticides, the emergence of widespread insecticide-resistance in wild mosquito populations is a strong motivation to explore new insecticidal chemistries. For these studies, Ae. aegypti and An. gambiae were treated with commercially available plant essential oils via topical application. The relative toxicity of each essential oil was determined, as measured by the 24-h LD50 and percentage knockdown at 1 h, as compared with a variety of synthetic pyrethroids. For Ae. aegypti, the most toxic essential oil (patchouli oil) was ∼1,700-times less toxic than the least toxic synthetic pyrethroid, bifenthrin. For An. gambiae, the most toxic essential oil (patchouli oil) was ∼685-times less toxic than the least toxic synthetic pyrethroid. A wide variety of toxicities were observed among the essential oils screened. Also, plant essential oils were analyzed via gas chromatography/mass spectrometry (GC/MS) to identify the major components in each of the samples screened in this study. While the toxicities of these plant essential oils were demonstrated to be lower than those of the synthetic pyrethroids tested, the large amount of GC/MS data and bioactivity data for each essential oil presented in this study will serve as a valuable resource for future studies exploring the insecticidal quality of plant essential oils. KeywordsAedes aegypti, Anopheles gambiae, plant essential oil, synthetic pyrethroid, terpene RightsThis article is the copyright property of the Entomological Society of America and may not be used for any commercial or other private purpose without specific permission of the Entomological Society of America. ABSTRACT Aedes aegypti and Anopheles gambiae are two mosquito species that represent significant threats to global public health as vectors of Dengue virus and malaria parasites, respectively. Although mosquito populations have been effectively controlled through the use of synthetic insecticides, the emergence of widespread insecticide-resistance in wild mosquito populations is a strong motivation to explore new insecticidal chemistries. For these studies, Ae. aegypti and An. gambiae were treated with commercially available plant essential oils via topical application. The relative toxicity of each essential oil was determined, as measured by the 24-h LD 50 and percentage knockdown at 1 h, as compared with a variety of synthetic pyrethroids. For Ae. aegypti, the most toxic essential oil (patchouli oil) was $1,700-times less toxic than the least toxic synthetic pyrethroid, bifenthrin. For An. gambiae, the most toxic essential oil (patchouli oil) was $685-times less toxic than the least toxic synthetic pyrethroid. A wide variety of toxicities were observed among the essential oils screened. Also, plant essential oils were ...

Plant essential oils synergize various pyrethroid insecticides and antagonize malathion in Aedes aegypti

“…aegypti were successfully determined in this study in order to later evaluate the synergistic potentials of plant essential oils compared with that of PBO. The LD 50 values obtained in this study for each insecticide were similar to those reported in the literature (Agramonte et al 2017;Norris et al 2015). In general, no insecticide LD 50 differed from values reported in the literature by greater than one order of magnitude.…”

“…The LD 25 and LD 50 values for Ae. aegypti exposed to each insecticide were calculated [ Table 1; permethrin data published previously in Norris et al (2015)]. The most toxic insecticide for Ae.…”

“…Of these oils, cinnamon bark and Origanum oils were also noted to be among the most toxic plant essential oils screened previously against Ae. aegypti adults (Norris et al, 2015). Texan cedarwood and geranium oils may contribute to the toxicity of deltamethrin and -cyfluthrin, respectively, by synergistic interactions as they were not among the most toxic oils (Norris et al, 2015).…”

Current and Future Repellent Technologies: The Potential of Spatial Repellents and Their Place in Mosquito-Borne Disease Control

“…The mechanism of action behind the toxicity of various plant compounds is complex and diverse. The mechanism of toxic action of various terpenoid compounds include inhibition of acetylcholinesterase, activity at octopamine and tyramine receptors, nicotinic acetylcholine receptor activity, and modulation of GABA-gated chloride receptors in insects [2]. Because of these diverse mechanisms of action and the potential of causing repellency via both antennal perception and fumigant toxicity, resistance to botanical compounds utilized as future repellent technologies may occur more slowly than toward synthetic contact and spatial repellents.…”

“…The parasites and viruses that are vectored by mosquitoes are responsible for the death of several hundred thousand people each year, with hundreds of millions more infected with debilitating consequences. Moreover, this disease burden is most substantial in developing countries, which lack the infrastructure and economic and educational resources necessary to properly control the spread of mosquito-borne disease [2]. …”