Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - REVOLINC (Revolutionizing Insect Control)

Teaser

According to the World Health Organization (WHO), vector-borne diseases account for 17% of infectious diseases leading to more than one million deaths each year. This includes by order of importance Malaria transmitted by Anopheles mosquitoes and arboviruses transmitted by...

Summary

According to the World Health Organization (WHO), vector-borne diseases account for 17% of infectious diseases leading to more than one million deaths each year. This includes by order of importance Malaria transmitted by Anopheles mosquitoes and arboviruses transmitted by Aedes mosquitoes like Dengue, Chikungunya, Yellow fever and Zika. Awareness of the toxicity of insecticides to living organisms and ecosystems is leading a growing number of countries to reduce the number of approved molecules. Moreover, resistance to pyrethroids, the most common class of insecticides used against insects, is spreading, which could result in its disuse in the short-term. Many countries are thus looking for alternative vector control methods against mosquitoes among which genetic control shows promises.

The REVOLINC project (ERC Consolidator grant no. 682387) aims at developing environmentally-friendly alternatives to fight insects invasions through the development of biological technologies to control three types of pest insects (mosquitoes, tse-tse flies and Mediterranean fruit flies), in particular Aedes albopictus (a major vector of arboviruses), and Ceratitis capitata (a major pest for agriculture), two species that are presently invading Europe and Glossina palpalis gambiensis (a major vector of trypanosomes in Africa). We want to improve the “sterile insect technique” (SIT) which consists in mass rearing male insects, sterilizing them by radiation and releasing them into the environment, where they compete with their wild, non-sterile counterparts to reproduce. The objective is to reduce the fertility of the overall population and eventually cause its collapse. The “boosted sterile insect technique” (boosted SIT) consists in ensuring that sterile males contaminated by a biopesticide also transmit it to the females and kill them or their progeny.

Work performed

During the first period of the project, three contamination techniques allowing covering the sterile males with formulations of biocide so as to obtain the desired effect without reducing their survival/ quality were developed including ultra-low volume spraying, powder impregnation of chilled insects and an impregnated net.
We then tested several formulations of Pyriproxifen and strains of Densovirus in the laboratory and we are now initiating the semi-field and field trials. Using the lab results, we could demonstrate based on models that boosted SIT can reduce by over 95% the total release of sterile males required to circumvent dengue epidemics compared to SIT. More complex models integrating a spatial component and meteorological data are being developed.
We also developed all mass-rearing and irradiation protocols for Aedes albopictus, and tested a drone-release system in the field, allowing a homogeneous release of the sterile male mosquitoes without reducing their quality. The release system was protected through a world patent.
We initiated the development of two genetic sexing systems based on fluorescent markers on the sex loci or feeding larvae with dsRNAs targeting sex-determination genes to produce RNA interference. We participated to several groups of experts to implement risk analyses on the genetic control of mosquitoes including the SIT and initiated the permit requests to release sterile male in Reunion island.
Finally, a study of the acceptability has been initiated with the objective to account, beyond the single necessity of cutting edge scientific and technological research and development programs, the deep nesting between technology and society.

Final results

The progress already includes the development of contamination techniques of sterile males using biopesticides, the quantification of their impact on contaminated females and their fertility & fecundity in lab conditions. Using the generated knowledge, we demonstrated using models that boosted SIT could become a game changer in the fight against mosquito-borne diseases. In the same time, the full SIT package including mass-rearing, sterilization, sex-sorting, quality-control and drone release has been developed to be able to implement pilot field trials.
The major expected results towards the end of the project will be to generate an even more efficient sexing system to release only non-biting male mosquitoes and to prove the efficiency of our innovative integrated strategy in the field using at least one biopesticide.

Website & more info

More info: http://revolinc.cirad.fr.