Effective mosquito repellents

The worldwide threat of mosquito-borne diseases brought about the need for effective insect repellents. Local applications of insect repellents containing the chemical DEET (N,N-diethyl-3-methylbenzamide) are more effective than other synthetic or plant-derived repellents. The researchers at the Harvard School of Public Health in Boston, USA, conducted studies involving 15 volunteers to test the relative efficacy of four products containing DEET-based insect repellents against seven botanical products and another synthetic repellent containing a compound called IR3535 (ethyl-butyl-acetyl-amino-propionate). The researchers also tested three wristbands containing either DEET or citronella, a plant oil common in botanical insect repellents. These products were tested in a controlled laboratory environment in which the species of the mosquitoes, their age, their degree of hunger, the humidity, the temperature, and the light–dark cycle were all kept constant. They found that, overall, DEET products offered longer-lasting mosquito protection. A formulation with 23.8% DEET provided just over 5 hours of complete protection, according to the report. In comparison, the IR3535 product provided protection for only 23 minutes, and an average of less than 20 minutes for most botanicals, which were largely citronella-based. None of the wristbands were effective. Mosquitoes can transmit a number of diseases, including malaria, yellow fever etc. And in areas where such illness is a "substantial threat," non-DEET local application repellents cannot be relied upon for lasting protection.