How Pesticides Affect Reproduction of Aquatic Organisms

In a new study conducted by the North Carolina State University, researchers have found that pesticide exposure can affect the reproduction abilities of “water fleas”, causing them to produce more male offspring and creating reproductive issues in females.

According to the North Carolina State University pesticide study, Daphnia, an aquatic species also referred to as “water fleas”, is especially sensitive to environmental cues when determining sex in reproduction. The researchers discovered methyl farnesoate (Mf), a hormone the water fleas produce under certain environmental conditions, binds with a protein receptor and creates more male offspring than female.

"This work supports the hypothesis that exposure to some environmental chemicals during sensitive periods of development can cause significant health problems for those organisms later in life – and affect their offspring and, possibly, their offspring's offspring," says Dr. Gerald LeBlanc, a professor of environmental and molecular toxicology at NC State and lead author of a paper on the work. "We were looking at a model organism, identified an important pathway for environmental sex determination, and found that there are chemicals that can hijack that pathway."

During the study, researchers exposed the water fleas to different levels of insecticide that resulted in more male offspring and few offspring in total. At high concentrations of the insecticide, only male offspring were produced. At low concentrations, female offspring were produced, but they suffered from long-term reproductive health effects which caused them to have fewer offspring themselves.