Further drafting of the guidance on risk assessment and risk management of LM mosquitoes

The objective of the LM Mosquitoes project is to replace the vectors populations by non-vectors populations (transgenic mosquitoes), to stop the transmission.
This is a lofty project in its design but don’t we should consider it in the frame work of Integrated Vector management instead of thinking that transgenic mosquitoes are a silver bullet to the vector-borne diseases?
Indeed, the following concerns are to be considered.
Is the introduction of transgenic mosquitoes will be compatible with other vectors control programs? Indeed, the introduction of the transgenic mosquitoes should, for example, require the interruption of insecticide treatments to promote their installation. This situation will allow so other non transgenic vectors to continue the transmission of diseases.
In addition, is there no risk that parasitic strains, like Kdr gene in the Anopheles, avoid this resistance and make this tool not efficient?
There is also a risk of improving the vector capacity of transgenic mosquitoes to other parasites or virus. That could make possible the transmission of some diseases whose germs suffer the phenomenon of " parasitic impass" in the mosquito organism.

Dr Xavier PITROIPA

As Dr. Pitroipa has pointed out, one of the ultimate objectives of LM mosquitoes that is envisioned is to replace populations. However, it is almost certain that the first applications will be population suppression rather than replacement.

It is commonly misunderstood that either objective is incompatible with existing measures of integrated vector management. Indeed the objective in both cases is to increase the relative frequency - not the absolute number - of mosquitoes with a particular phenotype. This can be accomplished even more easily when the number of mosquitoes is small. Therefore, any control measure that does not specifically target the altered form is compatible with LM release. I am aware of no anticipated LM application that is not compatible with repellents, larval control, ITNs, IRS etc.

The possibility of resistance evolving to an LM mechanism of parasite interference must be anticipated when mechanisms are being selected and tested. In this event, the effect would be a failure of effect rather than a hazard.

A hazard would result if the resistant LM vector developed a higher capacity to transmit another disease agent (due to mutation subsequent to release presumably). It seems more likely that the agent would adapt to the LM vector with an altered phenotype. This definitely has happened recently with regard to chikungunya and Aedes albopictus and is a natural process that cannot be prevented. It might be minimized by modifying the mosquito so that numerous complementary effectors act against the same agent. At this time, such possible measures seem rather speculative.

Perhaps one of the forum readers could provide a rationale for why such a “better vector” change would be more likely to occur and become established in a LM mosquito rather than in a wild type.

Mark Q. Benedict
Atlanta, GA USA