Malaria, dengue, yellow fever, and the Zika and West Nile Viruses are major vector-borne diseases of humans transmitted by mosquitoes. According to the World Health Organization, over 80% of the world's population is at risk of contacting these diseases. Insecticides are critical for mosquito control and disease prevention, and insect insecticide resistance is on the increase; new alternatives with potentially different modes of action from current chemistry are needed.
Ivermectin (IVM) reduces the lifespan of malaria-transmitting mosquitoes after feeding on humans treated with IVM but limited data are available on the exact duration of the mosquitocidal effect of IVM. Daily mosquito feeding assays were conducted to determine this. Mosquito mortality was 70-100% when mosquitoes fed on mice, rats, or cynomolgus monkeys 1-2 days after the last IVM administration. The findings reported here, of a pronounced but short-lived mosquitocidal effect, makes the timing of IVM administration crucial to form a useful addition to anti-malarial drugs.