Methyl dihydrojasmonate and lilial are the constituents with an "off-label" insect repellence in perfumes

Insect repellents are widely used to fend off nuisance mosquitoes and, more importantly, to reduce or eliminate mosquito bites in areas where viruses and other vector-borne diseases are circulating. Synthesized more than six decades ago, DEET is the most widely used insect repellent. Plant-derived compounds are used in a plethora of commercial formulations and natural recipes to repel mosquitoes. They are also used as fragrances. We analysed Bombshell(®) to identify the constituent(s) eliciting a previously reported “off- label” repellence activity. The two major fragrance ingredients in Bombshell, i.e., methyl dihydrojasmonate and lilial, demonstrated strong repellence against the southern house mosquito, Culex quinquefasciatus, in laboratory assays. Both compounds activated a previously identified DEET-sensitive odorant receptor, CquiOR136. These compounds were also major constituents of Ivanka Trump eau de parfum. The methyl dihydrojasmonate content was higher in the Ivanka Trump perfume than in Bombshell, the reverse being true for lilial. Both Bombshell and Ivanka Trump eaux de parfums retained activity for as long as 6 hours in laboratory assays. Although wearing these perfumes may repel nuisance mosquitoes, their use as “off-label” repellents against infected mosquitoes is not recommended.