Up to 57 different pesticides are poisoning European honeybees and exacerbating the decline of bee populations worldwide.

This was a warning from researchers out of the National Veterinary Research Institute in Poland, who also highlighted a new method that can detect a huge array of pesticides in bees and help scientists get to the bottom of the problem of global honeybee decline.

Honeybees are falling in numbers worldwide, including in the United States, partly due to colony collapse disorder. It is unclear what directly causes CCD and how it works, but scientists implicate several factors that include pesticide use. For instance, the European Union has banned the use of neonicotinoid pesticides given the pesticide-bee decline link.

The insects play a crucial role in agriculture and the environment by pollinating more than 80 percent of crops and wild plant species in Europe alone, said lead study author Tomasz Kiljanek.

The Polish researchers reported that they developed a method that detects and analyzes 200 pesticides and metabolites in honeybees.

"We wanted to develop a test for a large number of pesticides currently approved for use in the European Union to see what is poisoning the bees," Kiljanek says.

Because of their sheer numbers, it is difficult to work out which pesticides are harming the bees, and combined effects and accumulation over time could pose greater dangers. Even at low amounts, pesticides can weaken the immunity of bees and allow parasites or viruses to crush the colony, warned Kiljanek.

The team used QuEChERS, a method currently used for detecting pesticides present in food, to probe more than 70 honeybee poisoning cases. In this analysis, they tested for 200 different pesticides simultaneously, along with compounds produced by pesticide breakdown.

A staggering 98 percent of the tested pesticides are approved to be used in the European Union.

According to the results, there were 57 pesticides present in the poisoned bees - a piece of the toxicity puzzle that science is currently trying to solve.

For the authors, this is just the start of the investigation on pesticide effects on honeybee health, with their findings expanding knowledge on the matter and helping other scientists better study the risk of currently used and approved pesticides.

The findings were published in the Journal of Chromatography.

Previous research focuses on other reasons for the significant decline of pollinators worldwide, including climate change and disease. Diesel exhaust, for instance, changes half of floral scents that honeybees employ in their search for flowers - something suggested as a contributor to bee population decline.

A United Nations report released in February warned that hundreds of billions of dollars' worth of food crops will suffer from this decline, threatening global food supply if nothing will be done.

Two of five bee, butterfly, and pollinating critter species are becoming extinct, while their vertebrate peers are only slightly better off with one of six facing extinction.

Photo: Mike DelGaudio | Flickr

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