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Waking up in the face of resistance?

July 7, 2011 - 15:54 -- Bart G.J. Knols

Sometimes you come across articles that blow your mind. You read them and feel your heartbeat increasing. Each sentence you finish makes you wonder more what is going on here. What the politics are, who's really behind it, and what the goal of it is....

Well, a good example of an article like that is the one published in Nature News this week, written by Declan Butler. Butler has a keen interest in malaria, and he has always covered stories for Nature on the topic. This time he discovered something malariologists discovered long time ago: that if you throw chemicals at insects, they will develop resistance.

That is of course a good thing. Resistance to pyrethroids highlighted as an issue of serious concern in a reputable journal like Nature. Finally, and I repeat finally, there is word from WHO (in this case through Dr. Jo Lines) that mass uptake of pyrethroid treated nets leads to rapid development of resistance. I am very pleased to hear Dr. Lines saying that, as it is finally recognition of the fact that 'if you do what you did, you will get what you got'. Recognition of the treadmill of insecticide resitance is a good start towards moving in a better direction and learn from past mistakes.

In 1998, I published an article in which I predicted the occurrence of wide-spread resistance (and behavioural resistance) once ITNs would flood Africa. The flooding happened, and so did resistance pop up everywhere, now hitting us hard. Although I was right with my predictions, I regret that I ever published that article, as for years afterwards I was condemned in 'bednet circles'.

Interestingly, Dr. Janet Hemingway is now also acknowledging the trouble, but the 'banging of the drums' has come from all directions to the IVCC (after all, the 'I' stands for 'Innovative' so one would expect alternative solutions to pyrethroids (i.e. non-chemical tools) to be taken up seriously within the IVCC).

I recall a meeting with Dr. Hemingway and Dr. Kate Aultman (now with the Gates Foundation) in Yaounde in 2005, to discuss our results with entomopathogenic fungi, which had been published in Science that same month. Although this was a major opportunity to bring a new (and resistance-proof) technology to the front, it was not taken seriously.

Dr. Lines commented in Science on the use of fungi as a biological control tool by saying 'I have seen plenty of false technological dawns' (Science, 308, p. 1531). Such a statement has had major impact on the ability of scientists around the world to move biological control of adult mosquitoes forward.

Thus, it is very helpful now that both Dr. Lines and Dr. Hemingway acknowledge the problems with pyrethroids - perhaps even that if we start using new active ingredients on the same scale as now with treated nets, we will end up in the same situation. I am pleased with this, as hopefully they (and others, notably funding organisations) will now become more amenable towards funding other, non-chemical options.

It is also very good to read that Dr. Lines recommends use of a different class of chemicals for IRS, not pyrethroids that are used on nets. Good that we had a forum discussion on this on MalariaWorld more than a year ago and reached that same conclusion back then already...

(Please fill out the new poll on this matter, thank you)


Submitted by Guest (not verified) on

Whilst there is a growing body of scientific evidence that entomopathogenic fungi can have the required efficacy against mosquito vectors of malaria, there has not yet been any demonstration that fungal biopesticides can be produced with the right target product profile (TPP). For example, a fungal biopesticide will need to be formulated in such a way that it will be stable during transport and storage without the requirement for refrigeration and will also have the necessary residuality on all key surface types (mud, cement and wood). Assuming that such a TPP could be realised for a fungal biopesticide, it would also have to be produced in sufficient quantities to supply the demand of vector control programmes in Africa and at a price that is cost competitive with conventional insecticide formulations.