From: Esther Tola, SciDevNet, More from this Affiliate
Published February 22, 2010 09:35 PM

Insecticide beats DDT in early trials

Malaria researchers in Benin say they may have found a replacement for DDT in areas where mosquitoes are resistant to common insecticides.

Indoor residual spraying (IRS) of insecticides is a major part of malaria control. But worries over toxicity and environmental persistence have led to calls for DDT to be phased out, and mosquitoes are growing resistant to widely used pyrethroid insecticides. Alternatives are expensive and short-lived.


Researchers writing in Malaria Journal this month (8 February) say that a modified version of the insecticide chlorpyrifos-methyl (CS) could provide a solution.

CS is too short-lived to be feasible or cost-effective for malaria control when applied directly. But coating tiny droplets of it using a process known as microencapsulation boosts its effectiveness and longevity.

Raphael N'Guessan — a researcher at the Entomological Research Centre of Cotonou (CREC) — and colleagues sprayed experimental huts in Ladji, a village in southern Benin, with this modified CS, DDT and the pyrethroid lambdacyalothrin.

Spraying with CS killed almost all Anopheles gambiae mosquitoes. DDT killed half and lambdacyalothrin just under one third. A similar pattern at lower levels was seen in Culex quinquefasciatus mosquitoes.

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