A popular Indian clove-based mosquito repellent is a false economy

Abstract

Insect repellents are important prophylactic tools for travelers to and populations living in endemic areas of malaria, dengue, encephalitis, and other vector-borne diseases, and the first line of defense against emerging arboviruses. However, the cost of daily applications of even the most affordable and the gold standard of insect repellents, DEET, is still high for low-income populations where repellents are needed the most. An Indian clove-based homemade recipe has been presented as a panacea. We analyzed this homemade repellent and confirmed by behavioral measurements and odorant receptor responses that eugenol is the active ingredient in this formulation. Prepared as advertised, this homemade repellent is ineffective, whereas 5X more concentrated extracts from the brand most enriched in eugenol showed moderate repellency activity against Culex quinquefasciatus and Aedes aegypti. DEET showed higher performance when compared to the 5X concentrated formulation and is available in the same market at a lower price than the cost of the ingredients to prepare the homemade formulation.

Odorant receptors from Culex quinquefasciatus and Aedes aegypti sensitive to floral compounds

“…Because pathogens might be transmitted during a bite by an infected mosquito, there is understandably a great deal of interest in unraveling the olfactory aspects of human-mosquito interactions (Bradshaw et al, 2018) to explore ways of reducing mosquito bites. However, plant nectar sources are often essential for mosquitoes because they increase mosquito life span and reproductive capacity (Lahondère et al, 2019) and long-living mosquitoes are more dangerous (Tan et al, 2019). Therefore, understanding how mosquitoes find plants/flowers is also important for reducing the transmission of vector-borne diseases.…”