Science

Pesticide shown to decrease bees’ intelligence

By Lisa Carr

The world’s honeybees are under threat. With many problems and challenges facing bee species, they are all but disappearing. Since the late 1990s, beekeepers across the globe have witnessed a huge decline in colonies. One US beekeeper in 2006 reported a 90 percent die off from his 3000 hives and US National Agricultural Statistics estimate that there has been a 60 percent reduction in the total number of hives from 1947 to 2008.

The biggest cause of this drastic reduction has been bee-killing pesticides. Another cause is industrial agriculture leading to monocultures, reducing biodiversity and destroying pollen species. Parasites and pathogens and climate change also play a part in this decline.

The main focus is however on pesticides. It is widely believed that increasing usage of chemical pesticides and herbicides are killing bees directly, or restricting their ability to function. Bees unwilling ingest the synthetic chemicals whilst doing their daily pollination rounds and bee populations have been pushed to the brink of collapse.

One pesticide has come under scrutiny in the lab environment to fully assess the damaging consequences it has on bees. The substance, chlorpyrifos is a widely used insecticide and concerns regarding its toxicity have not gone unnoticed. Researchers from New Zealand’s University of Otago found that bees collected from 51 hives across 17 locations had detectable low levels of chlorpyrifos. This in itself isn’t a surprising find. From previous studies, it is known that chlorpyrifos is detectable in air, water and plant samples in regions where it hasn’t even been sprayed as it is an incredibly volatile substance that can spread vast distances.

In the same study, a separate number of bee subjects were fed with low levels of the pesticide. They were then subject to learning performance tests to assess the effect that the pesticide had on their general functioning.

It was found that the bees who were fed chlorpyrifos had worse odour-learning abilities and recalled odours more poorly later. This has bad consequences for the individual bees as it reduces their ability to find pollen-rich flowers and food. It also makes it difficult for the bees to locate and identify other bees and animals to detect threats. Bees are highly dependent on their sensitive olfactory system.

Dr Elodie Urlacher who lead the study said “Honeybees rely on such memory mechanisms to target flowers, chlorpyrifos exposure may be stunting their effectiveness as nectar foragers and pollinators.”

This study helped quantify the levels of chlorpyrifos that causes sub-lethal effects in bees. It highlights that sometimes, though death doesn’t occur immediately, damaging effects can have a drastic impact on the functioning of the species and can lead to species decline later on.

Greenpeace has highlighted a number of solutions to save and restore bee species. They say these are mere ‘common sense actions’ and call for an increase in organic farming methods that eliminate the use of pesticides. A key point is that they want to ban seven of the most dangerous pesticides across the world as well as preserving wild habitats to protect the species that the bees pollnate.

Cardiff Council has backed plans to restore habitats in the city with bright flowers to provide for bee species. The campaign known as ‘Urban Buzz’ aims to help declining pollinator species by creating urban havens of wild flowers and parks.

Similarly, Cardiff University has backed plans to be a ‘bee-friendly campus.’ The University’s Redwood Building in conjunction with the Pharmacy School will be renovated and a green area will be built around the building with bee-friendly flowers and plants.

It’s extremely important that measures like this spread globally. Bees are the world’s more important pollinator of food crops. Our food chain is reliant on this pollination; one third of the food we eat wouldn’t be available if it wasn’t for bees.

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