Taiwan - Exploring Sugar Bait Methods for the Control of Dengue Fever and Malaria

Issues and Objectives

There are currently over 3,000 species of mosquitoes in the world, with 132 species recorded in Taiwan. Vector-borne infectious diseases such as dengue fever, malaria, chikungunya, Japanese encephalitis, yellow fever, and Rift Valley fever are all listed as legally notifiable infectious diseases in Taiwan. Early methods of controlling vector-borne infectious diseases in Taiwan primarily involved spraying pesticides, but the extensive use of insecticides led to adverse consequences such as mosquito resistance, ecological damage, and public resentment. Although the central government has changed its strategy, local governments have failed to implement policies effectively, resulting not only in indiscriminate spraying (techniques and methods), misuse (concentration and dosage), and wasteful spending (public funds). Researchers have utilized the mosquitoes' need for sugar to replenish their energy to develop the attractive toxic sugar bait (ATSB) method. This method uses sweet-smelling poison bait to lure and kill mosquitoes, thereby preventing the occurrence of mosquito-borne infectious diseases.

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Improvement Measures Taken

Between 1998 and 2013, an average of 50 million to 100 million people were infected with dengue virus each year, of whom approximately 500,000 developed severe dengue hemorrhagic fever, and 12,500 died. In light of this, the World Health Organization (WHO) designated 2014 World Health Day as "small bite, big threat," emphasizing increased awareness and intervention in the prevention and control of vector-borne infectious diseases such as dengue fever. In 2014, Taiwan saw a record high in locally transmitted dengue cases for that period. Although the central government has established the highest guiding principle of "primarily eliminating breeding grounds and supplementing with pesticide spraying," excessive and repeated spraying of pesticides is still frequently carried out. As a result, not only has the epidemic not been eliminated quickly, but the indiscriminate spraying and arbitrary increase in pesticide concentration have led to environmental pollution and waste of public funds. Therefore, scientists have developed a set of prevention and control techniques based on the mosquitoes' habit of needing sugar to replenish their energy—the poison sugar bait method. This method uses sweet-smelling poison bait to lure and kill mosquitoes, thereby achieving the goal of preventing mosquito-borne infectious diseases.

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Results

attractive toxic sugar bait, ATSB:

For mosquitoes, sugar syrup is a more readily available energy source than blood, so they feed on sugar syrup more frequently than blood. The sugar bait method utilizes the mosquitoes' need to ingest sugar syrup for energy, leading to the development of a method that mixes a small amount of chemical agents (insecticides) into the sugar syrup to attract and kill mosquitoes. In practice, this involves using floral or fruity scents combined with sugar syrup or molasses mixed with insecticides to lure and kill mosquitoes, thus achieving a disease prevention effect; the solution can even be sprayed directly on plants or used at bait stations to kill mosquitoes in large areas.

The use of ATSB for the prevention and treatment of malaria:

In 2010, a research team conducted experiments using sugar bait in Mali, Africa, targeting the malaria-causing mosquitoes *Anopheles gambiae* and *Anopheles arabiensis*. The main components of the attractive sugar bait (ASB) solution included local fruits (guava, cantaloupe), water, brown sugar, and beer. Edible dyes were added to confirm mosquito feeding, and a slow-release agent was added to preserve the scent. Boric acid was then added to create the ATSB solution. One week after spraying the ATSB solution, mosquito density decreased dramatically by approximately 90%. In 2012, in arid regions of Africa, a mixture containing over 75% local cactus juice, wine, and brown sugar was fermented outdoors for two days. Then, 1% boric acid and 1% antifungal concentrate were added to create the ATSB solution. The results showed that the sugar poison bait method could reduce the density of female mosquitoes by up to 95%. Based on the above studies, it can be seen that the sugar poison bait method is effective in killing malaria mosquitoes.

The use of ATSB for dengue fever prevention and control:

Researchers added boric acid to sugar bait solution (5% sucrose solution) and sprayed it on plant surfaces, conducting a series of indoor and outdoor experiments. The experiments found that spraying the sugar bait solution containing 1% boric acid was most effective; after 14 days, the mosquito mortality rate remained above 98%, but the effect diminished after 21 days. Outdoor experiments showed that the lethality decreased after 7 days of spraying, possibly due to climatic conditions. Besides boric acid, dinotefuran, as an active ingredient, showed good control of Aedes aegypti and Culex tropicae in indoor experiments, with a mosquito mortality rate exceeding 70% in field experiments. Eugenol (safrole), as an active ingredient, showed excellent control of Aedes aegypti, Culex tropicae, and Anopheles quadrimaculatus in both laboratory and field experiments, reducing mosquito populations by at least 50% within three weeks. Studies using Datnam as the active ingredient on non-target organisms in the wild showed that the target organisms were significantly affected by the sugar-coated bait, while other organisms were not greatly affected. This demonstrates that Datnam is a highly effective ingredient for mosquito control without harming non-target insects.

Due to climate change, the future climate will be more favorable for the survival of disease-carrying mosquitoes, which may increase the scale and severity of dengue fever outbreaks in Taiwan. The biological control strategy explored in this case, if assessed and deemed suitable for routine application in daily epidemic prevention, can be regarded as an adaptation strategy to strengthen the public health and epidemic prevention system in response to future climate change.

Glossary

Climate change risk assessment: Using effective assessment tools to understand the medium- and long-term impacts of climate change on various sectors, and to propose corresponding adaptation strategies and actions to reduce the risks brought about by climate change.

Case type:

Structural and physical options: engineering techniques or reinforcement of existing structures, integrated technology development

Social options: learning and exchanging disaster knowledge in the community, and developing and applying early warning information.

Institutional options: Establishing institutions at the economic, policy, and legal levels

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References

Exploring the potential application of sugar bait in the prevention and control of dengue fever and malaria, Xia Weitai et al. Epidemic Reports, Vol. 31, No. 16, August 25, 2015. DOI: 10.6524/EB.20150825.31(16).002

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Reference Websites

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