Plant-based insect repellents: a review of their efficacy, development and testing

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.

Figure 1

Moghul painting illustrating a man burning neem leaves near a river where biting insects would be present (^© Dr Sarah Moore)

Figure 2

A village herbalist in rural Yunnan, Southern China. This lady was a key informant for an ethnobotanical study into plants used to repel mosquitoes (^© Dr Sarah Moore)