Comparative toxicity of oxygenated monoterpenoids in experimental hydroalcoholic lotions to permethrin-resistant adult head lice

Abstract

The use of botanical compounds such as essential oils has recently become the subject of great interest as a natural means of pest control because of their ovicidal, larvicidal, or adulticidal activity against various insect species including head lice. We tested and compared the efficacy of pure oxygenated monoterpenoids that are main ingredients of essential oils of good biological activity. We used pulegone and citral, components of Aloysia citrodora, and geraniol, citronellol, and linalool, components of Geranium sp. oil. We found that citronellol and geraniol showed the highest knockdown and mortality effect (>60%) on adults of both sexes (50:50%) and third-stage nymphs. Pulegone, linalool, and citral showed knockdown percentages between 42 and 55%, and mortality percentages between 47 and 53%. A simple linear regression analysis showed statistically significant relationships between the studied toxic effects and viscosity of the monoterpenoids (p < 0.05), but not with their partition coefficient (log P).

Novel polymeric micelles for insect pest control: encapsulation of essential oil monoterpenes inside a triblock copolymer shell for head lice control

“…However, the addition of monoterpenes enhances the mortality of the formulations. The mortality of adults and eggs associated with the use of EOCs has been previously observed for similar under different experimental conditions and formulations (Toloza, Vassena & Picollo, 2008; Gonzalez-Audino et al, 2011; Gallardo & Mougabure-Cueto, 2012). …”

“…In a previous work, Gonzalez-Audino et al (2011) studied the efficacy of several oxygenated monoterpenoids in hydroalcoholic lotions against head lice. This study showed that a hydroalcoholic solution containing 60% ethanol was a good diluent of a 5% of pulegone, citral, geraniol, citronellol and linalool.…”

In vitro activity of ten essential oils against Sarcoptes scabiei

“…In fumigation bioassays, the toxic compounds are inhaled via the respiratory system. Therefore, compounds which are lipophilic and viscous might have better performance in contact bioassays, whereas in fumigation bioassays, the vapor pressure may determine the compound efficacy [36]. …”

Terpenes: Natural Products for Controlling Insects of Importance to Human Health—A Structure-Activity Relationship Study

“…Among the components of essential oils, 1,8-cineole, anisole, limonene, -pinene, linalool, menthone, -pinene, pulegone, and myrcene have demonstrated fumigant activity (KT 50 < 53 min) whereas eugenol, borneol, menthol, isomenthol, anethole, camphor, carvone, menthyl acetate, linalyl acetate, thymol, p-cymene, -terpinene, -terpineol, and 4-terpineol had no effect (KT 50 > 60 min) [3,11,13,19,20]. Moreover, Gonzalez-Audino et al [34] and Gallardo et al [35] reported that citronellol and geraniol had the highest toxicity on adults for immersion and topical application methods, respectively. It has been suggested that the mechanism of action of essential oil components could be due to competitive inhibition of the enzyme acetylcholinesterase (AChE, EC 3.1.1.7).…”