Heated battle: Microwaving insecticides to fight malaria

Bart Kahr's team applied heat using both a microwave and oven to modify the crystal structure of deltamethrin. [Courtesy]

In Kenya, a silent battle rages between humanity and one of its oldest foes; the mosquito. These tiny, buzzling creatures carry with them the deadly threat of malaria. But as with any war, the enemy adapts.

In this case, certain types of mosquitoes like anopheles gambiae, a type mostly found in coastal and western Kenya, have developed resistance to one of the most commonly used insecticides: deltamethrin.

However, all is not lost as a glimmer of hope shines from the halls of New York University where a team of researchers led by crystallographer Bart Kahr have found a way to make an old weapon new again with a groundbreaking discovery.

In a recent study published in the Malaria Journal, they revealed that by simply microwaving deltamethrin, its crystal structures can be rearranged without altering its chemical composition. This rearrangement breathes new life into the insecticide renewing its ability to vanquish even those mosquitoes that had developed resistance.

It was a discovery born from crystal growth experiments that led Kahr and his colleague to discover that DDT, an old insecticide from the last century has two crystal forms. One of which works better than the other. This sparked their curiosity and they began experimenting with the more modern deltamethrin.

Kahr's team applied heat using both a microwave and oven to modify the crystal structure of deltamethrin found in a commercial product known as D-Fense Dust. While the oven allowed for precise temperature control, they found that simply popping it in the microwave for five minutes worked just as well.

However, Kahr cautioned against using the same microwave for heating food and insecticides due to concerns about potential contamination and health risks associated with heating insecticides in a microwave that is also used for food.

This research could have a monumental impact on the fight against malaria in regions like coastal Kenya where some mosquitoes have developed resistance to deltamethrin. If Kahr's research is verified and found to be effective, it could also have significant implications in the insecticide industry.

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Manufacturers of deltamethrin-based insecticides could incorporate this new method of rearranging the crystal structure of deltamethrin using heat into their production processes.

"We just were surprised at how relevant it really was, and a little surprised that nobody looked at this before," Bart Kahr says of his discovery.