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■Bio-mathematics, Statistics and Nano-Technologies: Mosquito Control Strategies

11.3

EFFICACY OF DIFFERENT ESSENTIAL OILS AS MOSQUITO

REPELLENTS

11.3.1

Lemon eucalyptus oil

Used since the 1940s,lemon eucalyptus oil is one of the most well-known natural repel-

lents. Oil of lemon eucalyptus extract or PMD (para-menthane-3,8 diol) is highly effective

and long-acting mosquito repellent, similar to DEET, because it has a lower vapor pressure

than volatile monoterpenes found in most plant oils [18]. The Centers for Disease Control

and Prevention (CDC) have approved eucalyptus oil as the only plant - based repellent, for

use in disease endemic areas because of its proven clinical efficiency to prevent malaria and

having no risk to human health [19, 20]. Several papers have been published examining the

repellent effectiveness of lemon eucalyptus essential oil on different types of mosquitos.

Two research works found that plant-based spray that contains oil of lemon eucalyptus,

was the only DEET-free formula to deliver strong and long-lasting results on repellency of

disease-carrying mosquitos Aedes albopictus and Aedes aegypti [21, 22]. 20% PMD ap-

plied topically can provide 100% protection from A. Stephensi for 11 - 12 hours and 100%

protection for 2 hours against Ae. aegypti [23, 24]. Another study showed that 32% lemon

eucalyptus oil provided around 95% protection from mosquitos for 3 hours [25].

11.3.2

Immortelle oil

One of the most common used plant for obtaining immortelle essential oil is Helichry-

sum italicum. Immortelle essential oil is distilled from the flowering tops of the plant. It

is a fantastic oil that can promote normal healing of cuts and bruises, but it is also packs

a punch against mosquitos. An Italian study showed that immortelle oil from H. italicum

caused a high mortality rate against the mosquito A. albopictus. The results from this study

has shown that immortelle oil has significant amounts of oxygenated monoterpenes and the

highest level of sesquiterpenes (Neril acetate, α-Pinene, Limonene, γ-Curcumene, Neril

propionate and Nerol). By increasing the applied oil dosage from 200, 250 to 300 ppm,

there is an increase in efficiency in terms of the mortality rate of A. albopictus from 41.7,

through 81,7 to 100% mortality, respectively [26].

11.3.3

Lavender oil

Lavender essential oil, and the plant from which it derives, contains a compound known

as linalool, which produces a strong odor that is pleasant to humans and detestable to

mosquitos. This is primarily because it overloads their sensitive olfactory organs, pretty

much in the same manner as DEET [27]. A 2009 study found that lavender oil possessed a

93% repellant rate against mosquitos indoors and only around a 53% repellant rate against

mosquitos outdoors [28]. Taken together, lavender oil is one of the most effective natu-

ral mosquito repellants, especially when used as part of a larger natural repellant regi-

men. Barbara Conti et al. studied the insecticidal activity of essential oils extracted from

six Mediterranean plants, among which was Lavandula angustifolia against the larvae of