Tiny Doses of Pesticides are Killing Off Insects That Ensure Our Food Supply
Scientific Accommodation of the Science article "Pervasive sublethal effects of agrochemicals on insects at environmentally relevant concentrations"
Pollinators, like bees and butterflies, provide “1 in 3 bites of food that you eat”, according to the United States Department of Agriculture (USDA), but pesticides pose an ominous future for them. Over the past 10 years insect populations have been declining due to warming temperatures and pesticide use. Sublethal doses of pesticides, doses lower than required to kill insects, are of particular interest to scientists because we know the least about them, but are the types of quantities that insects interact with. These understudied interactions are endangering our food supply.
No one was sure how big the problem really is, until Dr. Lautaro Gandara published a new study in Science out of the The European Molecular Biology Laboratory and discovered sublethal doses of pesticides may explain mass insect loss over the past decade. They tested 1024 pesticides and found that over 600 of them altered normal behaviors in flies, butterflies, and mosquitos by impairing their mobility. After exposure, insects were unable to fly, walk, or run, impeding their ability to acquire food, reproduce, or escape predators, corroborating what many scientists suspected. Insects mobility is critical to ensure sufficient pollination of crops.
The researchers noted that a 4 degree increase in temperature made the sublethal doses lethal. Current concerns surrounding climate change lead scientists to believe that pollinators may be at a larger risk than previously thought. Previous studies about pesticides in the environment show that temperature dictates how much and how fast a pesticide decomposes. Degraded pesticides are often more dangerous than pesticides. Pesticides and their byproducts end up in the air, water, or soil, exposing lots of unintended areas and organisms. Current testing does not account for realistic conditions in which pesticides are used, like varying temperature, or what pesticides break down into once they are in the environment.
Gandara is the first to investigate the magnitude and severity of sublethal pesticides exposures to insects. By developing a method to quickly and thoroughly monitor the health parameters of flies, mosquitos, and butterflies they were able to test over a 1000 of the most commonly applied pesticides. These pesticides include common household brands like round-up, which are already outlawed by 25 US states. Other pesticides the group looked at like chlorpyrifos have been pulled from shelves in the US by The Environmental Protection Agency (EPA) and abroad due to cancerous effects on humans and their offspring.
The role of agrochemicals are to stave off insects, rodents, and fungus from impacting crop productivity, but are impacting what are known as “non-target” organisms, like insects that do not impact, or increase yields. Though these pesticides effectively manage target pests like mealworms, grasshoppers, and beetles, they are also targeting bees, butterflies, and moths. Using broad-spectrum pesticides is the equivalent of heavily bleaching all of your laundry to get out a single stain on a t-shirt. You got the stain out, but the rest of your clothes are virtually unwearable.
Pollinators' role in food security is unwavering. Scientists are urging that these new findings, existing articles detailing pesticides in the environment, and the ways insects that contribute to the ecosystem be considered by policy makers to reform the testing procedures for new agrochemicals. Changes include testing sublethal effects, and assessing parameters that trigger or result in death rather than lethality alone. Mobility impairment is one example of an effect that leads to death. Enacting changes will promote the development of agrochemicals that can contribute to a growing global food demand without threatening the survival of insects that assure our food needs are met in the first place.