Mosquitoes are spreading microplastics back to land

Microplastics have become ubiquitous in the world’s oceans with these minute plastic pollutants permeating marine food chains. The tiny beads have even ended up in our own food by polluting table salt. That we’ve already known.

But here comes worse news: not only do microplastics get ingested by marine creatures, large and small. They are also consumed, unwittingly, by land animals like birds, thereby spreading far and wide across the food chain. And the polluting microplastics routinely make their switch from aquatic environments to terrestrial ones through a bane of many an animal: mosquitoes.

According to three researchers from the University of Reading in the UK, water-dwelling mosquito larvae consume microplastics as water-dwelling larvae. The microplastics can accumulate in the guts of the insects while the larvae metamorphose into adult mosquitoes. These mosquitoes with microplastics in their guts are then consumed in turn by frogs, birds, bats and other animals, which also ingest the microplastics, along with the mosquitoes, though a process called ontogenic transference. Many of these birds and bats, too, get eaten with the microplastics being passed on from prey to predator.

“The transfer of MPs to the adults represents a potential aerial pathway to contamination of new environments,” write the researchers who have published their findings in the journal Biology Letters. “Thus, any organism that feeds on terrestrial life phases of freshwater insects could be impacted by MPs (microplastics) found in aquatic ecosystems.”

Despite their small size, microplastics, once they accumulate in the digestive systems of animals, can cause health problems by taking space away from actual nutrients as they themselves remain undigested. Microplastics aren’t biodegradable and can take hundreds of years to break down in the natural environment.

“Much recent attention has been given to the plastics polluting our oceans, but this research reveals it is also in our skies,” notes Prof. Amanda Callaghan, a biological scientist at the University of Reading who was the study’s lead author. “This is eye opening research, which has shown us for the first time that microplastics are able to navigate several life stages in flying insects, allowing them to contaminate all kinds of living creatures who would not normally be exposed to them.”

She adds: “It is a shocking reality that plastic is contaminating almost every corner of the environment and its ecosystems.”