Researchers have known that agrochemicals like pesticides can cause bees to die. But a new analysis shows the dangers the bee population might be facing are severely underestimated — the interaction of agrochemicals, parasites, and hunger exacerbate the mortality rate of pollinators like bees.

This is because the combination of the three “stressors” affects bees’ ability to forage, their memory, and colony reproduction, a new study published in Nature journal showed. And the continued exposure of bees to agrochemicals will not only result in the decline of bees, but also threaten food security and natural ecosystems.

20,000 species of bees together pollinate 85% of food and crops globally. So far, one in six species has gone extinct — with major factors including pesticide use and loss of habitat.

The effects of the stressors individually are in themselves detrimental to bee populations. But the multiple agrochemicals being increasingly used in agriculture “synergistically” amplify the negative effect — “meaning that the number of bees that are killed is more than we would predict if the negative effects were merely added together,” Harry Siviter, one of the researchers, wrote in The Conversation.

“When we consider the prevalence of these substances [agrochemicals] in the environment, the picture begins to look very worrying.”

Moreover, it is not just bees; a number of pollinator species may be under threat due to the combined influence of manmade stressors that have become a part of modern agriculture.

In addition to the threat of pesticides, fungicides, and other agrochemicals, pollinators suffer hunger too. As pollinators, they rely on nectar from flowers. But large-scale industrial agriculture has resulted in the lack of wildflowers providing nectar. Further, industrial beekeeping and transport of honey-bees for the purpose of pollinating crops increases their exposure to harmful chemicals, threatening their survival, a commentary published in Nature noted.

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Current environmental risk assessment schemes may be underestimating ”the interactive effect of anthropogenic stressors on bee mortality and will fail to protect the pollinators that provide a key ecosystem service,” the study notes.

The research highlights the importance of policies to protect the health of pollinators. Bees are critical for the survival of many plant varieties that sustain human well-being, the Food and Agriculture Organization (FAO) of the United Nations notes.

Declining bee populations may lead to food insecurity due to the effect it will have on fruit, nuts, vegetables, and other sources of nutrition, leading to imbalanced diets. “Countries need to shift to more pollinator-friendly and sustainable food policies and systems,” said FAO’s Director-General José Graziano da Silva in 2019.

The policy on protecting pollinators should be a coordinated international effort based on the Precautionary Principle (PP), according to a recent study. “The PP means that when it is scientifically plausible that human activities may lead to morally unacceptable harm, actions shall be taken to avoid or diminish that harm: uncertainty should not be an excuse to delay action,” the paper noted.

“A failure to address this and to continue to expose bees to multiple anthropogenic stressors within agriculture will result in the continued decline in bees and their pollination services, to the detriment of human and ecosystem health,” the researchers said.