Disease Predictions Can Be Improved by Considering Mosquito Predators | Imperial News






How mosquitoes respond to predators should be included in disease models, say the researchers behind a new study.

They say the information can improve predictions of when and where there might be high numbers of human infections with mosquito-borne diseases. The research is led by scientists from Imperial College London and Pennsylvania State University and published today in eLife.

People have wondered for more than a century what mosquitoes eat and what it might mean for the diseases they carry. Dr Marie Russel

The study shows how the presence of different predators can lead to significant changes in the body and behavior of mosquitoes, which alters the likelihood that they transmit diseases to humans, including malaria, West Nile virus and dengue. .

For example, exposure to predators can lead to a reduction in the average body size of mosquitoes, resulting in a shorter lifespan and fewer offspring per mosquito, ultimately reducing the spread of disease.

Co-first author Dr Marie Russell, from Imperial’s Department of Life Sciences, said: ‘People have wondered for more than a century what eats mosquitoes and what it might mean for mosquitoes. diseases they carry. There are so many papers on specific predation interactions, and the large number of studies that have already been published is what allowed us to synthesize such a comprehensive meta-analysis.

Co-first author Dr Catherine Herzog, from the Center for Infectious Disease Dynamics at Pennsylvania State University, said: ‘Our findings about how predators affect mosquito traits and behaviors may allow modelers to more accurately predict outbreaks, which could lead to better public health. preperation. »

Food effects

Mosquitoes of different species are eaten by a wide range of predators, such as fish, insect larvae, spiders and amphibians.

Predators like these can have “consumption” effects on their prey – when prey is successfully eaten, reducing survival – or “non-consumption” effects – when feeding fails or the prey picks up the predator’s signals without feeding. attempted.

Illustration of mosquito life stages surrounded by other animals
The life cycle of the mosquito and its different predators

This second category of effects is not routinely included in disease dynamics models because the effects can be complex. However, by evaluating observations from the scientific literature dating from 1970, the multidisciplinary team was able to estimate the extent of these non-consumer effects.

They divided the observations into seven subsets based on the mosquito trait measured in response to predation, such as body size and egg-laying behavior.

Interactions with predators

The team also looked at the specific example of West Nile virus, cases of which are known to increase during drought conditions, but with unclear explanations as to why. They suggest that during drier periods, the places where mosquitoes usually lay their eggs – permanent, often rural bodies of water like ponds – become too crowded with predators.

The increased threat of predation could cause mosquitoes to seek out smaller, more temporary egg-laying sites often found in urban environments, such as puddles in tires or watering cans. This leads to more encounters with humans, which increases the risk of infection.

In addition to improving predictive power, allowing local authorities to be better prepared for disease outbreaks, the study results could also help public health practitioners decide which predators to use as effective biological control agents to reduce disease. local spread of mosquito-borne diseases.

The researchers now hope to repeat their analysis for other disease-spreading insects, such as aphids, which damage agricultural pests, and chinch bugs, which transmit Chagas disease.

“Consumer and non-consumer effects of predators impact mosquito populations and have implications for disease transmission” by Marie C. Russell, Catherine M. Herzog et al. is published in eLife.

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