Nuclear Technique Can Help Control Disease-Transmitting Mosquitoes

IAEA Deputy Director General Aldo Malavasi explains the sterile insect technique at an IAEA press briefing on the Zika virus. (Photo: D. Calma/IAEA) 

Countries from around the world are showing increased interest in the use of the sterile insect technique (SIT) to suppress the populations of mosquitoes that transmit, among others, the Zika virus, said Aldo Malavasi, IAEA Deputy Director General and Head of the Department of Nuclear Sciences and Applications. The technology can become part of integrated mosquito control programmes in IAEA Member States.

SIT is a form of pest control that uses ionizing radiation to sterilize male insect pests that are mass-produced in special rearing facilities. It has been successfully used worldwide for over 50 years for various agricultural insect pests, such as fruit flies, tsetse flies, screw worms and moths. Its deployment against disease-transmitting mosquitoes, such as the carrier of the Zika, Chikungunya and Dengue viruses, is ongoing with some pilots already successfully completed and others showing promising results.  

Although conventional insecticide-based mosquito control methods have proven to be effective in controlling mosquitoes under certain conditions, resistance to insecticides is increasing and public health officials are constantly looking for new ways to tackle these pests.

In SIT, sterile males are released systematically from the ground or by air over the targeted areas, where they mate with wild females, which then do not produce offspring. As a result, when applied in combination with other control methods, this technique can suppress populations of insect pests. The SIT is among the safest and most environmentally friendly, and therefore sustainable, control methods available, and is usually applied in integrated campaigns to suppress insect pest populations. The IAEA, in partnership with the Food and Agriculture Organization of the United Nations (FAO), is spearheading global research in the development and application of SIT.

Applying SIT-based approaches requires substantial research and customization of the technique to the insect’s biology. “Mosquito control using this technology at an industrial scale is still in early stages, with successful pilot programmes in Italy, Indonesia, Mauritius and China showing encouraging results,” said Konstantinos Bourtzis, a molecular biologist at the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture. “It is like cars in the 1890s: it works but will need to undergo further development and refinement,” he said.

Mass-reared insects, males and females, are free of the disease. Nevertheless, one of the key technical challenges being researched is to have an effective system to separate male from female mosquitoes before irradiation. This is because female mosquitoes in the wild are the carriers of disease, and they need to be eliminated from the mass-rearing production line so that only the sterile males are released in to the wild. While this technology is being perfected, an alternative method is available to ensure that any female accidentally released cannot transmit the disease and is sterile.

In the past decade, through various IAEA projects, several countries have requested and received essential training, equipment and technology in SIT application against mosquitos. A recent training in Latin America reinforced managerial and technical skills of experts in the region. FAO/IAEA experts together with researchers from other countries are also researching ground and aerial methods for releasing sterile mosquitoes into the wild. Once countries have reared a sufficient number of sterile males, trial releases can begin.

During IAEA Director General Yukiya Amano’s current visit to Central America, several countries expressed interest for technical support in this area. He discussed possible ways in which scaling-up SIT research and development could help Member States to control mosquito populations that carry the Zika and other viruses. Experts in Latin America and the Caribbean already have considerable experience in using SIT against fruit flies and the screwworm.

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Last update: 10 March 2016