Mosquitoes might be small insects but pose danger to one's health. Dengue is one of the detrimental diseases caused by Aedes aegypti, a species of mosquitoes. An increase in the population of these creatures is a big problem that threatens human health. Insecticides are one of the chemically available things that can eradicate such problem. Although they are the key to the dilemma, a recent study in Costa Rica showed that mosquitoes evolved resistance against it. Aside from this, it was also stated that their predators did not keep pace with that evolution thus having its population increase.
The research started when ecologist, Edd Hammil from Utah State University noticed the problem while conducting research in the orange plantations in Northern Costa Rica.
"We felt like we were getting a lot more mosquitoes in plantations than in pristine areas and started to wonder why," said Hammil.
After the said observations, their team searched for the reason behind it. They found a whole community of larvae including the mosquitoes' species of Wyeomyia abebela between the overlapping leaves of bromeliads. It is a group of plants that can be usually found in the warm parts of America, according to National Geographic.
According to the researchers, the bromeliads found in the plantations have been treated with insecticides for more than 20 years. Although the orange plantations had been treated with insecticides, they found out that it has twice the population of mosquitoes as the pristine forest. Aside from this, the damselfly larvae, which is the major predator of the mosquitoes were missing in action.
In their research, they tested and compared the tolerance of the plantation mosquitoes with the mosquitoes found in the forest. They found that the plantation mosquitoes tolerated concentrations ten times higher than the forest mosquitoes. Additionally, the damselfly does not develop the same resistance.
According to insect ecologist, Den Yee of the University of Southern Mississippi, the resistance of a dangerous group of insects is a major problem in the world especially mosquitoes that spread diseases like dengue. Moreover, a phenomenon called competitive release survivors of insecticides treatment can bounce back the population within a generation which can be of another concern.
"Since you've decreased the density of mosquito larvae, you've enabled those larvae to grow bigger, because now more resources are available per unit animal," explained Yee.
From the given observation, if both insecticides and its corresponding predators cannot control the increase in the population of the mosquitoes there, the situation poses a threat since mosquitoes maybe carriers of a deadly pathogen.
