A new study concludes glyphosate, the world’s most widely-used herbicidal chemical compound, weakens the immune system of insects, including a particular type of malaria-carrying mosquito. The results of the study suggest glyphosate, by weakening the immune system, makes mosquitoes more likely to transmit malaria to humans.

Researchers from Johns Hopkins’ Bloomberg School of Public Health found that glyphosate weakens insect immunity (the study focused on one species of mosquito and moth) by inhibiting melanin production. 

Melanin is best known as a pigment. It’s what gives humans their skin color and protects from the sun’s ultraviolet rays. But in the insect world, the pigment also plays a critical role in immune function. 

The researchers picked the particular species of moth and mosquitio because evolutionary speaking, they are distant, which means that the findings could have broad implications for the insect world. Glyphosate, suggested the researchers, could make insects more susceptible to microbial pathogens. 

Declines in some insect populations have led to concerns among scientists that other common chemicals, including glyphosate, may also be causing harmful disruptions to ecosystems, says a press release by Johns Hopkins, which adds that prior research suggests that glyphosate may have adverse effects on honeybees and other insect species.

In 2001, glyphosate was found to weaken fungi by inhibiting their production of melanin, a compound that helps pathogenic fungi resist the immune systems of animals they infect.

Because insects play critical roles in the global ecosystem, “Disrupting their populations could in turn have major adverse effects on people, for example in agriculture, and even in the realm of infectious diseases,” the press release warns.

Co-author and lead researcher of the study, Daniel Smith, PhD, said, “Mosquitoes exposed to glyphosate were less able to control Plasmodium infections they would have otherwise resisted, which hints that glyphosate exposure may make them better vectors for malaria.” 

“These results raise concerns about the increasing use of glyphosate in regions of the world where malaria is endemic,” added Smith.

The researchers are now studying the long-term, multi-generational effects of glyphosate on insect populations.

Previous studies conducted on rats showed that glyphosate exposure causes genetic changes that leads to increased rates of disease in subsequent generations. 

To read the full press release click here. To read the study abstract click here.