As bees continue to decline, scientists have found many contributors, including climate change and landscape transformation. Now they’ve added another: glyphosate.
In recent years, glyphosate, a herbicide best known as the active ingredient in Roundup which is used to regulate plant growth and kill unwanted plant species, has become a matter of public concern as it is unclear whether or not it is harmful to the health of humans and other animal organisms.
First registered in the United States in 1974, glyphosate is applied annually to 298 million acres, or a quarter of the agricultural land in the United States, making it one of the most commonly used herbicides.
A recent study earlier this month found that exposure to glyphosate can alter a bumblebee’s ability to maintain hive temperature, which is essential for bees’ ability to feed and reproduce for increase the size of the colony.
Anja Weidenmüller, who led the study, has been studying the thermoregulatory behavior of bumblebees for more than a decade. For this study, Weidenmüller prioritized the long-term effects of glyphosate on bumblebee behavior rather than looking at the immediate 24-48 hour timeframe normally used to determine whether glyphosate is immediately lethal to bumblebees.
Unlike many laboratory studies, bumblebees have been studied in environments of resource limitation and environmental stressors, as most organisms would in the natural world. In fact, while bumblebees have declined, scientists have found that multiple factors play into this decline, including climate change, landscape transformation, and harmful chemicals used in agriculture, such as pesticides. As a result, bumblebees have experienced a severe decline in recent decades: a 2021 US Fish and Wildlife Service report found that over the past 20 years, populations have disappeared or become rare in 16 states, and sightings of bees have decreased by approximately 90%.
” While these [things] come together, an effect of an insecticide or pesticide can be very different from what usually tests for these organisms in laboratories,” Weidenmüller told EHN.
To mimic this complex environment, the researchers placed a brood of bees in the lab and exposed the bees to stressors such as glyphosate, and limited their sugar water to replicate the resource limitations they would be exposed to in the agricultural landscapes.
This study found that when exposed to glyphosate for just four hours, a bumblebee’s ability to maintain brood temperature decreased by 25% when resources were limited, which could affect bee health and impair their ability to reproduce, resulting in population decline.
“[The study] emphasizes the importance of these multiple stress factors for bees and their health; these risky times of resource limitation are often overlooked in labs,” Emily May, pollinator conservation specialist and agricultural manager at the Xerces Society, told EHN.
Extensive research has shown that the conservation of bumblebees, and bees in general, is crucial for the survival of crops and wild ecosystems. Bees are effective pollinators and pollinate 80% of the world’s flowering plants, including food crops.
“We really need them to be able to have these thriving systems, both for our food production and for wild ecosystems,” May said.
Food systems are largely dependent on pollinators and conserving biodiversity may be more beneficial in the long term to human health and agricultural production than the chemicals used in modern agriculture for food yield and pest control, have discovered by researchers.
“Agrochemicals may not be so important for increasing yields,” said James Crall, a professor at the University of Wisconsin-Madison who studies bees and plant-pollinator interactions. Crop pollination has been found to improve produce yield more than increased fertilization.
Although glyphosate is currently approved for use in the United States, at least 43 countries have banned or restricted the use of products containing glyphosate. Although there is research focused on the effects of glyphosate on humans and other organisms, such as the US Toxic Substances Agency’s acknowledgment of links between glyphosate and cancer, there are still potential effects to long term that we may not yet be aware of. aware.
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