How the use of geraniol as a repellent and an insecticide can help win the battle against crawling and flying insects
Geraniol is a safe and effective, natural origin, Biocide active ingredient
Researchers have recently found geraniol is a natural and effective repellent to use in biocidal products to protect humans and animals from microorganisms and insects.
Here’s the Wikipedia definition of a biocide:
“A biocide is defined in the European legislation as a chemical substance or microorganism intended to destroy, deter, render harmless, or exert a controlling effect on any harmful organism by chemical or biological means.”
An urgent need to replace Petrochemical biocides by natural biocides
Here’s the actual situation concerning insecticidal and repellent actives:
- There’s an increased demand from the public for safe and effective repellents, insecticides and pet products.
- Resistance to synthetic chemical insecticides, such as Pyrethroids, has developed in various insect populations, especially mosquitoes and bed bugs.
The demand from the public has led to the mass marketing of plant-based products that claim to repel or kill insects. So how do we measure the quality of new insecticidal / repellent actives?
What makes a good and sustainable insecticide or repellent
- Effective against a broad range of insects
- Can be easily applied to skin without irritation
- Can be sprayed indoors and outdoors, won’t damage clothing, fabrics or plastics
- Pleasant, non-chemical odour
- Chemically stable
- Non-toxic to humans and animals
- Environmentally safe from his manufacture through application
- Adequate duration of efficacy
- Competitively priced
Is geraniol effective for use in biocidal products?
To date, many products and efficacy claims have been made demonstrating that Geraniol is an attractive Biocide active ingredient. Geraniol meets all of the criteria listed above.
There have been numerous peer reviewed scientific publications on Geraniol products confirming their effectiveness.
In addition to repellent and insecticidal properties, Geraniol has also been demonstrated to have antimicrobial properties.
Geraniol (3,7-dimethylocta-trans-2,6-dien-1-ol) is a volatile, acyclic monoterpene alcohol with the chemical formula C10H18O.
Geraniol has a low mammalian toxicity and is biodegradable.
It has been extensively tested and found effective against several species of mosquitoes, moths, dog and cat fleas, head-lice and, ticks, as well as poultry red mites.
Geraniol has been marketed and used as the active ingredient in candles, Impregnated polymers, diffusers, aerosols, body sprays, and body gels.
It is believed that geraniol and other monoterpenes, when used in sub-lethal doses, excites insect receptors, disrupting the host odor profile, repelling the insects.
The scientific community realizes that the key to combating resistance to lethal insecticides could be to use sub-lethal doses of natural repellents, creating a “safe space” between host and vector (or pest).
Geraniol has great potential to become a widely used, important Biocide active ingredient.
Encapsulation of geraniol biocide improves effectiveness and longevity
Researchers have pointed out that the volatility of Geraniol is a factor that could lead to its decreased effectiveness over time.
Strategies such as microencapsulation enables to curb this phenomenon and increase the effectiveness of this compound.
Depending of the application, there are several encapsulation technologies that can help increase the longevity.
Geraniol as an insecticide (PT18)
Geraniol is not a nerve agent and does not use the same Mode of Action as synthetic chemical biocides. This helps minimize the ability of insects to become resistant to Geraniol.
There appears to be a consensus among published scientific literature that geraniol is toxic to insects, even at low concentrations, usually under the controlled conditions in laboratories. It should, however, be noted that the higher the concentration of geraniol used, the faster the toxic effect was seen. As well, higher concentrations may be needed for different species as insects do not always respond the same (Reis et al. 2016).
Lucia, A., et al. (2017). Novel polymeric micelles for insect pest control: encapsulation of essential oil monoterpenes inside a triblock copolymer shell for head lice control.
The study showed that even at relatively low concentrations (1.25 wt%) in micelles, monoterpenes had considerable bioactivity against head lice. The authors conclude that incorporation of compounds into anti-lice formulations using micelles is a safe and viable alternative for the fabrication of bio-sustainable insecticide formulations.
Chuaycharoensuk, T. et al. (2012). Assessment of geraniol-incorporated polymers to control Aedes albopictus (Diptera: culicidae).
Results of this study showed that terpenoid alcohols (geraniol) were toxic to both mosquito species. The LC50 (Lowest concentration with 50% mortality) values for geraniol and Aedes aegypti after 2 h exposure was an average of 71.44 μg cm-2, while the 4 h mark had an LC50 of 58.41μg cm-2. Geraniol was not evaluated at 24h. Tests on Anopheles quadrimaculatus showed geraniol was the most toxic compound yielding the lowest LC50 value (31.88 μg cm-2) at 2 h, and at 4 h (25.24 μg cm-2). At 24 h exposure, the LC50 was 25.29 μg cm-2. Overall, geraniol was one of the top most toxic compounds tested against Aedes aegypti and Anopheles quadrimaculatus.
Geraniol as a repellent (PT19)
Müller, G. C. et al. (2009). Efficacy of the botanical repellents geraniol, linalool, and citronella against mosquitoes.
The authors concluded that geraniol had significantly more repellent activity than citronella or linalool in both indoor and outdoor settings and against 4 mosquito species. Under the uniform conditions of the experiments, all substances repelled significantly more mosquitoes than the unprotected control. Furthermore, the repellents tested were more active when in the form of a continuous release diffuser than in candle form.
Müller, G. C. et al. (2008a). Indoor protection against mosquito and sand fly bites: a comparison between citronella, linalool, and geraniol candles.
The authors conclude that geraniol was better at repelling sand flies and mosquitoes than were linalool or citronella. They also concluded that 5% geraniol candles used indoors best fit repellency criteria outlined by the EPA. Geraniol provided greater indoor protection than the other two essential oil candles tested.
Zhu, J. J., et al. (2015). Comparisons of antifeedancy and spatial repellency of three natural product repellents against horn flies, Haematobia irritans (Diptera: Muscidae).
The authors concluded that all three natural product repellents effectively repel biting horn flies, exhibiting both feeding deterrence (contact repellency) and spatial repellency. They proposed an interesting strategy using geraniol, that develops an effective push-pull relationship between a suitable repellent (geraniol) and an attractant-baited horn fly trap, that can be used on cattle in the field. Since SPME was not used in conjunction with laboratory assays, it remains unclear as to why the volatility rate of geraniol was greater in the field.
We also found that density of insects being repelled needs to be considered when determining the concentration of geraniol used in a product and when determining what re-application time to place on a product label (Goodyer 2010; Pavela 2016). Is the product being used in high or low biting pressure environments? In high biting pressure environments, a higher concentration of geraniol might be recommended.
Finally, the use of geraniol as a single active ingredient versus use with other compounds may be a factor in its efficacy. One study points to geraniol as a component of essential oils and hypothesizes that a synergistic effect with other components explains the strong performance of citronella essential oil versus geraniol alone (Deletre et al. 2016). However, other studies found that geraniol as a single active ingredient out-performed citronella in repellency (Müller et al. 2008a; Müller et al. 2008b). It must then be left up to the developers of insecticides and repellents to test and use geraniol alone or in combination with other compounds.
The Biocidal Product Regulation and Geraniol Biocide suppliers
Since September 1, 2015, a biocidal product cannot be made available on the EU market unless either the substance supplier or the product supplier is included in the Article 95 list for the Product Type to which the product belongs.
TerpeneTech Ltd., is an approved supplier of Geraniol for use in biocidal products under the Biocidal Products Regulation (EU) No. 528/2012.
Registering or labelling a product with geraniol biocide
Geraniol is under evaluation and benefits to the transitional period scheme.
The transitional regime is defined by Article 89 of Regulation ( EU) No 528/2012: it is the period of time during which the making available on the market and use of biocidal products are governed by the national provisions in force in each Member State, pending approval of all the active substances they contain at European level. When all of a product’s active substances have been approved, the transitional regime no longer applies and this product must be authorised in accordance with the BPR.
French Guide lines gave a good understanding of the requirement that should be accepted in most of the countries.
Guidelines labelling biocidal products
Forming a Geraniol Product dossier/Family Consortium Task force
Consortium Task Forces are a good way to:
- Reduce company costs by sharing registration costs with other companies who have parallel goals.
- Share testing and development costs with complementary partners.
- Should seek to have the optimum number of Consortium members
- Our Biocide Consultants will help to build Consortium structure, internal rules to insure cooperation success.
If you want to learn more about geraniol biocide, feel free to contact us here.