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esistant insects should have PBO on all surfaces so that
the mosquitoes cannot avoid contacting both insecticide
and synergist at the same time.
What is Piperonyl Butoxide
Piperonyl butoxide (PBO) is a synergist which has long
been used to improve the performance of pyrethroid
insecticides especially household aerosols. Synergists are
chemicals that lack insecticidal activity of their own but
enhance the insecticidal performance of other chemicals.
How does Piperonyl Butoxide combat resistance
All insects, whether susceptible or resistant, have enzymes
that can metabolise insecticides into harmless components.
Some of these enzymes, known as cytochrome P450s, are
powerful oxidising agents that can detoxify an active
ingredient before the desired effect is achieved; PBO is a
powerful inhibitor of these enzymes and therefore blocks
this action.
In resistant insects the activity of these enzymes can
be greatly enhanced which can significantly reduce the
efficacy of an insecticide. PBO acts on these enzymes in
resistant insects and inhibits the breakdown or the
metabolism of insecticides, rendering the insecticide more
effective. PBO also increases the activity of pyrethroids to
susceptible insects, so adding PBO to an LLIN has a benefit
even in areas where there is no resistance.
There are many scientific papers which demonstrate
the impact of PBO on pyrethroid resistance, and some
specifically highlight the impact on permethrin resistance.
See for example: Evidence of multiple pyrethroid resistance
mechanisms in the malaria vector Anopheles gambiae sensu stricto
from Nigeria. Awolola, T.S. et al., Transactions of the Royal Society
of Tropical Medicine and Hygiene Vol: 103, Issue: 11, Pages: 1139-
1145 (2009).
Piperonyl Butoxide Key Points:
• Inhibitor of P450 enzymes.
• Enhances insecticide penetration.
• Used in many household aerosols and space sprays
products.
• Not an insecticide but a synergist.
• Low mammalian toxicity.
• Known and used for >50 years.
Olyset Plus Regeneration
Rapid regeneration of surface active ingredients after
washing -- and therefore the provision of an almost
continuously available insecticide plus PBO barrier against
mosquitoes -- is required to maximise the protective effect.
This is especially important in areas where resistant mosquitoes
have been found. The rate at which permethrin
and PBO migrate from the internal reservoir in the fibre
to the surface of the net (known as the ‘bleed rate’) has
been adjusted in Olyset Plus to provide a rapid rate of
regeneration, making the net active again within 1 – 2
days after washing.
Full efficacy in less than 2 days after washing.
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