Plastic pollution is spreading through the food chain, and flying insects might be partly to blame.
Scientists from the University of Reading have found that mosquito larvae can retain tiny plastic fragments in their bodies long after they’ve matured into winged adults.
“Larvae are filter feeders that waft little combs towards their mouths, so they can’t actually distinguish between a bit of plastic and a bit of food,” Amanda Callaghan, a biological scientist at the University of Reading, said in a statement. “They eat algae, which are more or less the same size as these microplastics.”
Since flying insects are eaten by birds and bats, they could provide a “potential new pathway” for plastics to enter the food chain beyond direct consumption, she added.
“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,” Callaghan said of her study, which was published in the journal Biology Letters.
Callaghan’s team started with Culex pipiens mosquito larvae, which readily ingested fluorescent plastic microbeads, similar to those used by some personal-care products as a means of mechanical exfoliation. Observing as the larvae matured into non-feeding pupae and then adult mosquitoes, they noticed that the levels of microplastic remained more or less unchanged.
While microbeads are manufactured in that size range on purpose, microplastics can stem from disparate sources—the abrasion of larger plastic items in waterways, say, or the shedding of polyester clothing in the wash. They’ve been found in the gastrointestinal tracts of fish and seabirds, in drinking water and even as far afield as the Antarctic. And though several countries, including the United States, have banned intentionally added microbeads in cosmetics, research suggests that microfibers from synthetic garments pose the more pernicious threat.
“It is a shocking reality that plastic is contaminating almost every corner of the environment and its ecosystems,” Callaghan said.