Key highlights:
- Dengue, which began with just a few dozen cases in Bangladesh around 2000, escalated into a significant health concern, peaking at over 100,000 known cases in 2019
- Currently,sterile insect technique is undergoing trials in several countries, including Brazil, Cuba, Germany, Greece, Italy, Mauritius, Mexico, Spain, and the USA
- Bangladesh has received machinery and equipment valued at over €70,000, with an additional €56,000 worth of equipment in the import pipeline
Mosquitoes rank among humanity’s deadliest adversaries due to their capacity to transmit diseases such as dengue, malaria, Chikungunya, and Zika, causing 17% of all infectious diseases worldwide. Dengue,which began with just a few dozen cases in Bangladesh around 2000, escalated into a significant health concern, peaking at over 100,000 known cases in 2019.
Worldwide, the number of dengue cases reported to the World Health Organization has surged eight-fold in the past two decades.
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During its worst dengue outbreak, Bangladesh sought help from the International Atomic Energy Agency (IAEA) in August 2019. Within a month, the IAEA responded by recommending the use of the sterile insect technique (SIT) to control Aedes albopictus(Asian tiger mosquito), the dengue virus carriers.
In the subsequent 5 years, Bangladesh has faced even more severe outbreaks, with increasing infections and fatalities from mosquito-borne diseases. Encouragingly, scientists have progressed in breeding sterile male Aedes mosquitoes in insectaries, reaching a point where they can release these mosquitoes into the environment to test their effectiveness in reducing the mosquito population.
However, scientists have recently discovered that the initially selected area for deploying sterile mosquitoes is no longer suitable for SIT validation.Scientists at the Atomic Energy Research Establishment (AERE)program are discussing with Dhaka North City Corporation (DNCC) officials the potential deployment of sterile mosquitoes in Uttara or Mirpur.
What is SIT?
The Sterile Insect Technique (SIT) was developed in the late 1950s and has been widely applied in the management of agricultural pests such as the Mediterranean fruit fly, false codling moth, New World screwworm, and tsetse flies.
Itis an eco-friendly method for pest control that involves mass-rearing target insects and sterilizing them with radiation. Sterile males are then distributed to infested areas where they mate with wild females, resulting in no offspring and gradually decreasing the wild insect population.
Fighting Mosquitoes with Their Own Weapons
Implementing the SIT for mosquitoes involves several challenges. The first is feeding and rearing mosquitoes for irradiation and release. Traditionally, gamma ray irradiators have been used for mass sterilization in SIT programs. Research and development have improved the cost-effectiveness of mass rearing.
For example, using aluminum and plastic instead of stainless steel for racks and cages has made large-scale rearing more feasible.
Since only female mosquitoes bite and transmit diseases, it is essential to release only sterilized males. In Aedes mosquitoes, males and females can be separated at the pupal stage because female pupae are larger. However, this method is not always precise due to factors like diet, rearing conditions, population density, and other environmental factors.
To improve sex separation in Aedes mosquitoes, scientists have developed a genetic sexing strain that produces red eyes in females and black eyes in males. This innovation is expected to enhance sex separation in SIT applications.
How SIT SquashedMosquitos in Multiple Nations?
Currently, SIT is undergoing trials in several countries, including Brazil, Cuba, Germany, Greece, Italy, Mauritius, Mexico, Spain, and the USA.
In a report named “Cuba Trial: Successful Elimination of Mosquitoes Using Nuclear Technique,” the IAEA Office of Public Information and Communication announced that “a test run of a SIT initiative in a Havana resulted in a remarkable decrease of up to 90% in Aedes aegypti mosquito population in 2022. Moreover, initial findings suggest that instances of mosquito-transmitted diseases were entirely eradicated in the final two months of the trial.”
Mosquitoes in Fort Myers, Florida, have shown signs of developing resistance to insecticides.To address this, a pilot project supported by the IAEA and the Food and Agriculture Organization(FAO) is utilizing sterile mosquitoes to reduce the mosquito population. This initiative, which began in Fort Myers, was previously tested on Captiva Island, about 30 miles away, during a successful pilot project from 2020 to 2022.
Male mosquitoes were mass-reared, sterilized, and released to mate with wild females. At the peak of the releases, approximately 400,000 sterile males were released per week on Captiva Island, resulting in a significant population reduction in 2020 and complete suppression in 2021 and 2022.
In Guangzhou, China, a pilot project was conducted over a 32.5-hectare area on two relatively isolated islands in the Pearl River. Approximately 200 million irradiated mass-reared adult male mosquitoes exposed to Wolbachia bacteria were released, achieving a reduction of over 80% in mosquito populations.
SIT trials targeting Aedes albopictus in the Emilia-Romagna region of Italy, have demonstrated a reduction in mosquito populations by around 80%, contributing significantly to the control of vector-borne diseases in the region.
| Countries Using SIT | Success Rate (%) |
|---|---|
| Havana | 90 |
| China | 80 |
| Italy | 80 |
€126,000 Equipment Enhancement for Sterile Mosquito Initiative
AERE currently has a weekly production capacity ranging from 10,000 to 15,000 sterile mosquitoes. However, due to the dense mosquito population in Dhaka, it may be necessary to release up to 10 million sterile mosquitoes per week to effectively impact the aedes population.
Bangladesh has made significant strides in training scientific personnel and enhancing the rearing capacity of sterile mosquitoes through radiation technology. Additionally, it has received machinery and equipment valued at over €70,000, with an additional €56,000 worth of equipment in the import pipeline. There is optimism that these efforts will lead to successful deployment by the end of the current SIT program, slated to conclude in December 2025.
As the battle against mosquito-borne diseases intensifies, the innovative Sterile Insect Technique (SIT) emerges as a formidable weapon in our arsenal, offering hope for a future where deadly outbreaks are curtailed and communities thrive without fear. However, Preserving the delicate nature of mosquitoes is crucial, especially during their release into the environment in SIT programs.
Researchers in Brazil, alongside experts from the Joint FAO/IAEA Division, have identified drones as a potential solution. Their study demonstrated that drone-based release minimizes harm to the insects while also proving to be more economical and expedient compared to ground-based release methods.
