Pesticide threatens food security by attacking queen bee

A common pesticide used on crops compromises a queen bumblebee’s ability to lay eggs, threatening her colony with extinction. PHOTO| FILE| NATION MEDIA GROUP

A common pesticide used on crops compromises a queen bumblebee’s ability to lay eggs, threatening her colony with extinction, according to a study published in the journal Nature Ecology & Evolution.

Lab experiments used doses of thiamethoxam — one of the controversial neonicotinoid family — that corresponded to what a queen bee might encounter in the wild.

KILLER PESTICIDE

Exposure to the chemical shifted the timing of colony formation and reduced the number of eggs by more than quarter and raised the chance of colony collapse by at least 28 per cent.

“This showed that the impact of neocotinoids on colony founding, by itself, increases the risk of an exposed bumblebee population going extinct,” Mark Brown, a professor at the University of London, and co-author of the study, said.

Neonicotinoid pesticides are widely used in agriculture, but recent studies have suggested a strong link with declining bee populations, especially over the last decade.
As a result, in 2013 the European Food Safety Authority (EFSA) imposed a partial, temporary moratorium on their use, pending the result of a review scheduled for completion later this year.

However, scientists are still trying to pinpoint how the insecticide affects bees, which are crucial for the pollination of crops ranging from almonds and apples to peaches and plums.
Previous studies ignored a key aspect of the bumblebee life cycle, which is the colony founding stage.

“As successful colony founding is key to the size of bumblebee populations, and bumblebee queens feed on crops and plants that can be contaminated by neonicotinoids, this life-cycle stage could be key in understanding the impacts of neonicotinoids,” the researchers said.

Pollinators also have to confront parasites, predators, bad weather and a lack of food. A global review last November concluded that some 1.4 billion jobs and three-quarters of all crops depend on pollinators, mainly bees.

There are some 20,000 species of bees responsible for fertilising more than 90 per cent of the world’s 107 major crops.

Last year, the United Nations said 40 per cent of invertebrate pollinators — particularly bees and butterflies — risk global extinction.

Neonicotinoids — lab-synthesised pesticides based on the chemical structure of nicotine — appeared also to be linked to declines of butterflies, birds and aquatic insects.

Widely used to treat flowering crops, they are designed to be absorbed by the growing plant and attack the nervous system of insect pests.

Bees are also under threat from varroa mites, which have also been shown to cause colony collapse. However. research by the Kenya-based International Centre of Insect

Physiology and Ecology (ICIPE), has shown that African bees are resilient to varroa mites, which have been implicated in colony collapse in Europe and America. The mite sucks the blood of bees at the larval stage and infects bees with the deformed wing virus, which has detrimental effects on the bees and their ability to pollinate food crops, thus leading to lower yields.

CONTROVERSY

Thiamethoxam is a chemical in the controversial neocotinoid family of pesticides. Neocotinoids are lab-sythesised pesticides based on the chemical structure of nicotine, which is known as a carcinogenic in humans. Neocotinoids are applied as a coating on the seeds of maize and other crops, and spread systemically throughout the crop, eventually ending up in the pollen of flowering plants. This exposes insects that eat pollen, nectar or the plant itself to harm. In some countries, traces of neocotinoids have been found in honey samples. Neocotinoids can leach into ground water, and they can persist in the environment for years after use.