Chemists create new crystal form of insecticide, boosting its ability to
fight mosquitoes and malaria

Date:
October 12, 2020
Source:
New York University
Summary:
Through a simple process of heating and cooling, researchers have
created a new crystal form of deltamethrin -- a common insecticide
used to control malaria -- resulting in an insecticide that is up to
12 times more effective against mosquitoes than the existing form.



FULL STORY ========================================================================== Through a simple process of heating and cooling, New York University researchers have created a new crystal form of deltamethrin -- a common insecticide used to control malaria -- resulting in an insecticide that is
up to 12 times more effective against mosquitoes than the existing form.


==========================================================================
The findings, published in the journal Proceedings of the National Academy
of Sciences (PNAS), may provide a much-needed and affordable insecticide alternative in the face of growing resistance among mosquitoes.

"The use of more active crystal forms of insecticides is a simple and
powerful strategy for improving commercially available compounds for
malaria control, circumventing the need for developing new products
in the ongoing fight against mosquito-borne diseases," said Bart Kahr, professor of chemistry at NYU and one of the study's senior authors.

"Improvements in malaria control are needed as urgently as ever
during the global COVID-19 crisis," added Kahr. "The number of deaths
from malaria in Africa this year is projected to double as a result
of coronavirus-related disruptions to supply chains. We need public
health measures to curtail both infectious diseases, and for malaria,
this includes more effective insecticides." Malaria is a major public
health challenge worldwide, with more than 200 million cases and 400,000
deaths reported each year. Insecticides such as deltamethrin can prevent
the spread of diseases carried by mosquitoes and are often sprayed indoors
and on bed nets. However, mosquitoes are increasingly becoming resistant
to insecticides, leaving researchers and public health officials searching
for alternatives with new modes of action.

Many insecticides, including deltamethrin, are in the form of crystals --
the research focus for Kahr and fellow NYU chemistry professor Michael
Ward. When mosquitoes step on insecticide crystals, the insecticide is
absorbed through their feet and, if effective, kills the mosquitoes.

As part of their research on crystal formation and growth, Kahr and Ward
study and manipulate insecticide crystals, exploring their alternative
forms. In their PNAS study, the researchers heated the commercially
available form of deltamethrin to 110DEGC/230DEGF for a few minutes and
let it cool to room temperature; this resulted in a new crystallized
form of deltamethrin, composed of long, tiny fibers radiating from a
single point.

When tested on Anopheles quadrimaculatus and Aedes aegypti mosquitoes
-- both of which transmit malaria -- and fruit flies, the new crystal
form of deltamethrin worked up to 12 times faster than the existing
form. Fast-acting insecticides are important for quickly controlling
mosquitoes before they reproduce or continue spreading diseases.

The new form also remained stable -- and able to rapidly kill mosquitoes
-- for at least three months.

To simulate how the two forms of deltamethrin would perform in stemming
the spread of malaria, the researchers turned to epidemiological modeling
that suggests that using the new form in indoor spraying in place of
the original form would significantly suppress malaria transmission,
even in regions with high levels of insecticide resistance. Moreover,
less of the new form would need to be used to achieve the same effect, potentially lowering the cost of mosquito control programs and reducing environmental exposure to the insecticide.

"Deltamethrin has been a leading tool in combating malaria, but it faces
an uncertain future, threatened by developing insecticide resistance. The simple preparation of this new crystal form of deltamethrin, coupled with
its stability and markedly greater efficacy, shows us that the new form
can serve as a powerful and affordable tool for controlling malaria and
other mosquito- borne diseases," said Ward.


========================================================================== Story Source: Materials provided by New_York_University. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Jingxiang Yang, Bryan Erriah, Chunhua T. Hu, Ethan Reiter,
Xiaolong Zhu,
Vilmali' Lo'pez-Meji'as, Isis Paola Carmona-Sepu'lveda, Michael
D. Ward, and Bart Kahr. A deltamethrin crystal polymorph for more
effective malaria control. PNAS, 2020 DOI: 10.1073/pnas.2013390117 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201012152049.htm

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