Cymbopogon citratus and Lippia multiflora essential oils as alternative repellent to DEET against Anopheles gambiae s.l. in Bobo-Dioulasso, Burkina Faso

Personal protective tools, such as repellents, play a vital role in preventing mosquito-borne disease transmission. Although N,N-diethyl-meta-toluamide (DEET), a synthetic repellent, is effective against insects, it may cause allergic reactions. Therefore, there is a need to explore effective alternative repellents exhibiting fewer side effects. Here, we assessed the repellent activity of essential oils (EOs) from Lippia multiflora and Cymbopogon citratus alone and in combination, against Anopheles populations, using the Human Landing Catch (HLC) method in Dogona, Burkina Faso. For this purpose, five concentrations (0.5%, 1%, 1.5%, 2% and 2.5%) of each EO and their combination were applied on 68 volunteers legs from 6 p.m. to 9 a.m. on two consecutive nights. Also, DEET and ethanol were used as positive and negative controls respectively. As results, overall, houses with volunteers to whom EOs had been applied showed a reduction in the mean human biting rate (HBR), both indoors and outdoors (combination EO, 2.5%: 1.5 vs. control: 46.75 b h−1 n−1). This combination exhibits an efficacy comparable to that of DEET (DEET: 2 b h−1 n−1). This repellent effect is likely attributable to the dominant compounds present in the EOs namely, neral (44.7%) and geranial (55.2%) in C. citratus, and β-caryophyllene (20.1%), p-cymene (14.6%), and thymol acetate (12.0%) in L. multiflora. When the two essential oils were combined, they exhibited a synergistic repellent effect, resulting in a long protection time. The use of EOs as repellents may reduce the number of mosquito infectious bites/human/night, thereby contributing to a lower Entomological Inoculation Rate (EIR = 0.77). This study highlights the promising repellent potential of C. citratus and L. multiflora EOs, against wild mosquito populations.