Mosquitoes can flourish in winter if conditions are right, new study says

Even in winter, temperatures may remain warm enough to allow mosquitos to thrive in certain breeding grounds, according to a new study from an interdisciplinary team of Texas A&M University researchers.

For the study published in the journal Scientific Reports, A&M researchers developed a mathematical model based on machine learning to precisely predict the local or microclimatic temperature within the breeding grounds of the Aedes albopictus mosquitoes, carriers of the chikungunya and dengue viruses.

“Our goal is to develop accurate and automated mathematical models for estimating microclimatic temperature, which can greatly facilitate a quick assessment of mosquito populations and consequently, vector-borne disease transmission,” said Madhav Erraguntla, associate professor of practice in the Wm Michael Barnes ’64 Department of Industrial and Systems Engineering. 

Responsible for around a million deaths globally, mosquitoes continue to wreak havoc to public health in many parts of the world. In addition to water, temperature plays a critical role at different stages in mosquitoes’ life cycle. Furthermore, the mosquitoes’ development, reproduction and survival can be mathematically modeled based on temperature.

Past studies have largely relied on ambient temperature, or general air temperature, to make predictions about mosquito populations. However, these calculations have not been precise since ambient temperatures can deviate from those within mosquito breeding grounds. Recognizing this shortcoming, scientists rely on sensors, called data loggers, to continually keep track of the temperature, light intensity and humidity within breeding grounds. Despite their advantages, these sensors are inconvenient due to their cost and long-term use.

“People have realized that the microclimatic conditions are important, but right now data loggers are the only way to keep track of temperature,” said Erraguntla. “We wanted to address this gap by automating the process of estimating microclimatic temperatures so that we can model the life cycle of mosquitoes accurately.”

For their experiments, the researchers placed sensors in common mosquito breeding grounds around Houston, including storm drains, shaded areas and inside water meters. In addition, they obtained information on ambient temperatures from the National Oceanic and Atmospheric Administration repository. With this data as training input to a machine learning algorithm, the computer model could predict the microclimatic temperatures for a variety of ambient temperatures and breeding grounds within 1.5 degrees centigrade. Further, the model now could even forecast microclimatic temperatures for any ambient temperature, precluding the need for sensors.

Next, they fed the values of the microclimatic temperatures to another mathematical model, called the population dynamic model, that tracks the life cycle of the mosquitoes. Based on the microclimatic temperature and other parameters, the population dynamic model could estimate the populations at different stages in the lifecycle including eggs, larvae, pupae and adult Aedes albopictus mosquitoes. 

Contributors includes Darpit Dave, Josef Zapletal and Mark Lawley from the industrial and systems engineering department; and Kevin Myles, Zach Adelman and Tyler Pohlenz from the Department of Entomology in the College of Agriculture and Life Sciences.