Dengue Fever Control: Reducing Mosquito Populations with Native Fish

The Faculty of Agronomy of the University of Buenos Aires (FAUBA) seeks, through biological control, to reduce the population of mosquitoes that transmit diseases. The initiative provides free advice and materials and focuses on ponds, reservoirs and other water bodies in CABA where the insect breeds.

With high temperatures come mosquitoes and the diseases they carry, such as dengue, Zika and chikungunya, which have a particularly strong impact on urban areas. In this context, a project of the Faculty of Agronomy of the UBA (FAUBA) of the City of Buenos Aires uses indigenous fish to reduce the population of these insects to their aquatic larval stage and thus reduce the proliferation of diseases. The initiative provides free advice and materials to institutions that have ponds, pools and other types of water bodies where the mosquito could breed and breed. Aedes aegypti.

Dengue is present in Argentina. In 2016 there were 42,000 cases and in 2020 almost 60,000. As it depends on the rains, in wet years there are bigger shoots. Although this year is quite dry, we should not wait for an epidemic to occur to solve the problem. It is necessary to carry out preventive policies and measures against the disease and the mosquito that transmits it”, explained Alejandro Koko López, Professor of the Chair of Aquaculture at FAUBA.

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How can it be avoided? “Before being a mosquito, the insect lives in water as a larva. Buckets and pots should be turned over so as not to collect water. However, there are spaces that cannot be emptied either because they contain a large volume of water or because they are used for irrigation. The initiative that we lead from the pulpit aims to use the biological control of the mosquito in waters for productive or recreational usesaid Lopez.

The project is based on “seeding” native fish that feed on mosquito larvae in ponds, fountains or swimming pools. “We use native species adapted to this type of environment and which resist a wide variety of environmental conditions and require very little maintenance effort. Moreover, by consuming the microfauna of aquatic ecosystems, they do not require a food supplement. Thus, as long as they live, they can keep the mosquito population at bay in a small aquatic environment. It is a long term strategy. An adult fish can consume up to 100 larvae per day“, he underlined. The initiative uses species such as Jenynsia lineata Yes Cnesterodon decemmaculatus, commonly called Madrecitas.

In addition, López spoke about the benefits of basing the project on biological control with native species. “We reduce the use of insecticides and repellents. Attacking larvae in a given aquatic system is more effective than driving away adult mosquitoes. The idea is that they reduce the population of larvae to zero. Although there are chemical compounds to control larvae, they are expensive and require constant application. On the other hand, by using native fish, we are not endangering other species in the ecosystem”.

The delivery of materials and advice is completely free. It can be a club, a school or a private institution. “Once we receive the orders, from FAUBA we visit the premises, we estimate how many fish will be needed depending on the volume of the body of water and we train those who will be in charge of the task. We are already farming native fish in 6 1000 liter tanks and hope to have a guaranteed large production,” the teacher said, adding that orders can be placed by email. [email protected].

Contents

delivery and tracking

zika, chikungunya, dengue fever, larvae, native fish, mosquitoes, biological control

The teacher said that it is simple to calculate how many fish each body of water needs. “The number of individuals per liter and the environmental conditions are taken into account. On the other hand, it is necessary to respect the animal welfare protocol of the UBA that governs any experimental vertebrate —Institutional Commission for the Care and Use of Laboratory Animals—. For example, if the pond receives a lot of sun, it is recommended to put plants or partial shade. We want the fish to live as harmoniously as possible. In all cases, fish populations adapt to the environment in terms of resources. If there are many, they breed more”.

After delivery, follow-up continues, which López says is simple. “A visual survey of the presence or absence of larvae is made. Finding a single unit is already an alarm and further action should be taken. In this case, we go back to see if there has been a problem and reinforce the number of fish if necessary. These preventive measures are complementary to decacharreo and other preventive measures against dengue fever.“.

Monitoring is essential because it gives us information or an alert. If required by the institution, there are FAUBA trainees who can carry out the task or provide the training. We’re not going to completely eradicate mosquitoes from the city, but the goal is to keep them as low as possible.“, he added.

soak up the problem

López said many people approach the chair of aquaculture with concerns about projects that require water bodies such as orchard ponds or growing vegetables in large ponds. “We listened to requests and we had round trips. As the demands exceeded us, we sought to serve as many people as possible and we did so in coordination with the National Ministry of Science and Technology through the PROCODAS program: Technological Projects for Social Inclusion”.

In this regard, he concluded:At FAUBA, we want to bring tools closer to the community. In particular, towards the Educational Pole of Villa Soldati, which is a property where there is a primary school, a college and kindergartens. Villa Soldati is a densely populated neighborhood with a vulnerable social situation, which makes it susceptible to being a hotbed of dengue infection. The idea is to be able to train the community in fish management and spread the dangers of mosquito-borne diseases.”.

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