Humanity has long recognised the essential role of pollinating bees and insects in sustaining life and health, so much so that generations of parents have used the phrase “the birds and the bees” as a metaphor and euphemism to help explain the mechanics of human reproduction to children.
Much like the phrase “there are plenty of fish in the sea”, it is also an idiom grounded in the assumption that bees, pollinators and nature will always be bountiful.
And yet, as a result of industrial-scale human pillage, the former abundance of sea fish is in steep decline across the world, a phenomenon our ancestors would surely have considered unimaginable. So, too, is there a global decline in wild bees and other essential pollinators.
Globally, nearly 90% of wild flowering plant species depend, at least in part, on the transfer of pollen by bugs and other animals, while more than 75% of our main food crops rely on nature’s pollination services.
It is against this backdrop that leading African scientists have urged governments and policy makers to give serious consideration to banning, restricting or tightening up regulations for neonicotinoid pesticides on this continent.
Neonicotinoids, or neonics, are a class of relatively new pesticides introduced to Europe and other parts of the world in the late 1990s. They were designed to be less toxic to birds and mammals than older pesticide groups such as carbamates and organophosphates. Yet they are non-selective when it comes to insects, killing both “pest” and non-pest species such as bees and other pollinators.
This is because neonics are potent and systemic neurotoxins. Unlike contact pesticides, which remain on the surface of the treated parts of plants, such as the leaves, neonics are taken up and transported throughout the plant system into the leaves, flowers, roots and stems, as well as pollen and nectar. Being water soluble, they can also spread far into the environment.
As a result, the use of some neonics was restricted in the European Union (EU) seven years ago. And mounting scientific evidence of their negative effects on bee species and insects led to a complete European ban in 2018 on the outdoor use of three neonics (imidacloprid, clothianidin and thiamethoxam).
While most of the evidence that led to this decision was based on research in Europe or the United States, it raised questions about whether similar action should be taken in Africa.
The Network of African Science Academies (Nasac) gathered experts from 17 African countries and reviewed more than 200 studies from 28 nations on the continent. Their recently published report concludes that “it is urgent to act now to prevent further deterioration in the sustainability of African agriculture”.
Nasac board chairperson Mostapha Bousmina said Africa needs a range of eco-friendly tools to increase farm productivity and ensure food security.
Experiences in Europe and the United States have demonstrated that some agrochemicals – neonics in particular – have serious, negative effects on ecosystem services such as pollination and natural pest control. “Taking advantage of the knowledge and experience outside Africa to try to avoid repeating those negative impacts on Africa’s rich and diverse ecosystems appears to be urgent in view of the rapid growth of intensive agriculture here,” said Bousmina.
While the main focus of the report is on neonics, the scientists said alternative pesticides (sulfoxaflor and flupyradifurone) were also entering the market and should be subject to the same level of scrutiny for potentially similar side-effects.
The scientists voiced concern that the 2018 EU action could encourage the pesticide industry to seek new markets in African countries for these banned pesticides, either to replace older pesticides or to increase current rates of neonic use.
“There is already evidence of widespread environmental contamination from neonicotinoids in Africa. Residues are found in honey from several countries, with some levels similar to or higher than levels found in Europe before the restrictions imposed by the EU.”
Apart from the impacts on the environment and food security, the scientists also red-flagged concerns around human health.
“It would be an oversight if we did not also mention the question of neonicotinoids’ toxicity to vertebrates (animals with backbones) and the potential for adverse effects on humans. Previously used pesticides (eg organophosphates) are very toxic to humans, and Africa has encountered many cases of deaths through exposure to pesticides in application, storage, disposal or contamination of food.
“One of the attractions of neonicotinoids has thus been the assumption that, since the human neurotransmitters are different from those of insects and less sensitive to the neonicotinoid group, acute toxicity is substantially less.”
While this might be true for the original active neonic pesticides, their metabolites, the products into which they break down, do not necessarily follow the same pattern. For example, desnitro-imidacloprid, which is a degradation product of imidacloprid, is more toxic to humans than to insects.
Moreover, the water solubility of neonicotinoids allows them to spread throughout the environment, contaminating soil and water.
“As a result, neonicotinoids have been detected in wild birds, rodents, fish, lizards, frogs and other animals … This extensive contamination raises concern over the potential uptake by humans and whether there could be health implications arising from sub-lethal effects of low doses over extended periods.”
Accidental exposure had already led to neurological effects in humans, and other studies suggest toxic effects on birds and mammals.
One study has found that imidacloprid in sparrows causes them to lose up to a quarter of their body mass, while another suggests that this pesticide causes deformities in white-tailed deer, including enlarged heart ventricles and damaged or missing thymus glands and scrotums.
Other harmful effects from lab experiments had been observed in rats (such as reduced sperm production, reduced pup weight, increased abortions and skeletal abnormalities) as well as in mice, rabbits, birds and fish.
“Particularly against the background of high exposures due to overapplication and misuse of neonicotinoids in Africa, these uncertainties and lack of data mean that effects beyond those on pollination and other ecosystem services extending to other wildlife and human health cannot be ruled out.”
Last year, Japanese researchers reported the first evidence worldwide to suggest that a toxic metabolite of one neonic pesticide (acetamiprid) may transfer to human foetuses at a high rate.
Doctor Go Ichikawa and colleagues from the Dokkyo Medical University said the discovery suggests a need to examine the potential neurodevelopmental toxicity of neonics and their metabolites in foetuses and newborn babies, whose brain blood vessels are more fragile than adults and therefore more vulnerable to drugs and toxins.
Traditional farming methods
The Nasac report says agriculture in Africa is in a state of rapid change, with the need to provide food security for a growing population.
Most of the continent’s farmers still rely on traditional methods of crop management, which includes making full use of natural pollinators and the pest control functions of nature.
Whereas Europe has about 11 million honey bee colonies, Africa has an estimated 310 million colonies. But farmers should also be aware that there are more pollinator species than just honey bees, and that many other insects should be seen as beneficial rather than as pests.
The report finds that despite a limited number of studies, there is clear evidence of a decline in pollinators in several parts of the continent.
The Ghana Cocoa Authority distributed neonics for free in Ghana, encouraging overuse and resulting in measurable levels of contamination in food and the soil. The resulting loss of natural pollinators led a national programme in 2017 that employed about 30 000 young people to hand-pollinate cocoa trees.
“When launching this programme, the chief executive of the Ghana Cocoa Board stated that ‘hand-pollination had become necessary because the natural agents for pollination – insects – had reduced in numbers through the spraying of chemicals’.”
The Nasac report notes that enforcement of regulations appears weak or non-existent in many African nations. In Ghana, the Environmental Protection Agency showed in 2007 that about 30% of pesticides on sale were either unlicensed or smuggled into the country.
“Some imports arrive in bulk and are repackaged into smaller containers, often carrying inadequate or misleading labelling. Many pesticide dealers do not have licences to operate and are believed to be selling banned or restricted pesticides.”
In some cases, chemical companies had driven and sponsored the pesticide authorisation processes and many farmers were not aware of the fundamental role of pollination in their crops.
“Many farmers also believed that the more toxic a pesticide is the better, and routinely spray above recommended doses, with multiples of between 1.5 and five times the recommended dose mentioned by some of the workshop participants.”
Government and pesticide industry respond
The Department of Agriculture, Land Reform and Rural Development says it has taken note of the Nasac report on neonicotinoids, but needs more time to consider the report and its recommendations before any regulatory policy decisions are taken.
CropLife SA, the industry organisation representing manufacturers, suppliers and distributors of crop-protection products, said it would attend the presentation of the Nasac report in Pretoria on 18 March.
Though CropLife SA published a position statement on neonics and honey bees in 2018, this has not been updated to take into account the possible implications for fauna and insects other than bees. But the industry group did say it believed the recent EU bans were owing to “extreme interpretation of overly conservative guidelines”.
“Some of the conclusions are not supported by the available data showing the typical behaviour in the real world, eg honeybee foragers consuming more than eight times their body weight in nectar per day.”
CropLife SA added that pesticide regulation in South Africa is based on a “risk approach” rather than a hazard approach.
“To illustrate the difference: hazard is the possibility of something causing harm, while risk is the probability of harm occurring. A bottle of bleach, for instance, is a hazard until someone drinks it, then it becomes a risk. Whether the bleach is on a shelf or locked in an impenetrable vault, the hazard remains, however, it only becomes a risk when someone does something stupid with it.
“Although a pesticide is categorised as hazardous, it does not mean its use should be banned. It can still be effectively used by farmers if, based on local safety assessments, it is proven safe and not to pose a non-manageable risk to human health and the environment.
“It is also important to take the agricultural environment into account, which means South African crops and climate are not identical to Europe and hence we may be able to use pesticides that are not required in the EU.”
CropLife SA said the results of numerous bee, pollen and nectar residue studies show that using neonicotinoids as the label recommends is safe. “It is simply disingenuous of scientists to extrapolate laboratory results through to field conditions without ever testing their hypotheses of toxicity in field conditions.”