Abstract
Plant-based repellents have been used for generations in traditional practice as a personal protection measure against host-seeking mosquitoes. Knowledge on traditional repellent plants obtained through ethnobotanical studies is a valuable resource for the development of new natural products. Recently, commercial repellent products containing plant-based ingredients have gained increasing popularity among consumers, as these are commonly perceived as “safe” in comparison to long-established synthetic repellents although this is sometimes a misconception. To date insufficient studies have followed standard WHO Pesticide Evaluation Scheme guidelines for repellent testing. There is a need for further standardized studies in order to better evaluate repellent compounds and develop new products that offer high repellency as well as good consumer safety. This paper presents a summary of recent information on testing, efficacy and safety of plant-based repellents as well as promising new developments in the field.
Highlights
Most plants contain compounds that they use in preventing attack from phytophagous insects
The primary functions of these compounds is defence against phytophagous insects, many are effective against mosquitoes and other biting Diptera, especially those volatile components released as a consequence of herbivory [1]
The fact that several of these compounds are repellent to haematophagous insects could be an evolutionary relict from a plant-feeding ancestor, as many of these compounds evolved as repellents to phytophagous insects [2], and this repellent response to potentially toxic compounds is well conserved in the lineage of Diptera (True Flies)
Summary
Most plants contain compounds that they use in preventing attack from phytophagous (plant eating) insects. 100% protection against Ae. aegypti for 4.5 hours 100% protection against C. quinquefasciatus for 8 hours 100% protection against An. dirus for 8 hours laboratory [34] study travellers to disease endemic areas should not be recommended citronella-based repellents [32] For those communities where more efficacious alternatives are not available, or are prohibitively expensive, the use of citronella to prevent mosquito bites may provide important protection from disease vectors [17]. This is an exciting discovery since PMD may be recovered from distillation of leaves of E. citroidora or chemical modification of citronellal [105]– available from plants of the genus Cymbopogon These plants are already commercially cropped in malaria endemic countries including South America, especially Brazil (6 million trees), southern China, India, Sri Lanka, Congo (Zaire), Kenya and most countries in southern Africa, where it is grown for essential oil production and timber [106]. Competing interests The authors declare that they have no competing interests Published: 15 March 2011
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