How do mosquito repellents work?

How do mosquito repellents work?

Repellents, strictly speaking are substances used to repel insects away from a source. Repellents play a major role in Integrated Pest Management. They are volatile chemicals and have low toxicity. A strong repellent repels the insect, which is fairly away from the source, but a mild repellent requires direct contact with the insect.

Insect repellents are mostly natural substances such as smoke, oils of citronella, lavender, eucalyptus and lemon. These natural repellents have now been replaced by synthetic repellents, which are most effective.

Most of the repellents used, are in the form of aerosols, creams, lotions, grease and oils. Evaporation, absorption by skin, dilution by perspiration, abrogation by clothing makes them less effective against the insects.

Carbon dioxide, excretory products and lactic acid present in sweat in warm- blooded animals act as an attractive substance for female mosquitoes.

The perception of the odour is through chemo-receptors present in the antennae of mosquitoes. The repellents block the lactic acid receptors thus destroying upwind flight and as a result the mosquitoe loses its contact with the host