Bees are falling like flies, new research reports, and it seems to be due to our use of pesticide cocktails.

We as a species are virtually completely dependent on bees and other pollinator insects, without whom we wouldn’t be able to put food on the table. A new meta-analysis that reviewed dozens of studies published over the last 20 years reports that the use of pesticide cocktails in agriculture greatly increases mortality among bees, more so than the substances taken individually. This is further exacerbated by the combined effects of agrochemicals, parasites, and malnutrition on bee behaviors and health.

The team concludes that current risk assessments significantly underestimate how much pressure bees and other pollinators are subjected to. The steep drop in pollinator numbers we’ve seen in crop and wild areas is a testament to these pressures, with potentially dire consequences for ecosystems around the world and our food security.

Bees in a pinch

“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 study concluded.

Pollinators, bees included, are the unsung backbone of our agriculture, but also of wild plant life. Given that insect populations are in decline all over the world, this naturally raises concerns for the health of pollinators going forward — and whether they can continue performing their ecological role or not. Roughly 75% of the world’s crops producing fruits and seeds for human consumption, including cocoa, coffee, almonds, and cherries, rely on pollinators.

Such concerns were the starting point for the current study. The authors explain that while bees seem to be able to resist the different stressors plaguing them today taken individually, they’re chafing under their weight taken together. The combined pressure from agrochemicals, parasites, and malnutrition is taking a toll on the species, greatly increasing the likelihood of death for individual bees and hives as a whole.

Intensive agriculture relies on the use of compounds such as fungicides or pesticides to protect crops and ensure large yields. “Interactions between multiple agrochemicals significantly increase bee mortality,” said co-author Harry Siviter, of the University of Texas at Austin. Furthermore, industrial-scale use of managed honey bees (in order to produce honey) increases the species’ exposure to parasites and diseases, which places even more strain on them.

The continued shrinking of areas with wild plants and wildflowers translates to less diverse pollen and nectar sources for bees, and arguably lower overall amounts of food they can access.

Although previous research has looked at these factors independently — including the effect different agrochemicals have on bees — the meta-study is the first one to look at their effect in aggregate. According to the team, the results strongly suggest “that the regulatory process in its current form does not protect bees from the unwanted consequences of complex agrochemical exposure”. Although the current analysis focused on honey bees, as most literature on the subject focuses on them, more research is needed on other pollinators, the team explains, as they might react differently to the stressors we’ve seen here.

Back in 2019, researchers were drawing attention to the fact that almost half of the world’s insect species were in decline, and a third of them were at real risk of going extinct by the end of the century. Leading causes for this decline are pesticide use and habitat destruction. Against that background, the warnings of this meta-study are all the more biting.

The paper “A cocktail of pesticides, parasites and hunger leaves bees down and out” has been published in the journal Nature.