By Dr. Silke Bollmohr, PhD, Environmental Science
The European Commission recently banned three of the most widely applied insecticides due to the risk they pose to bees and other pollinators. The April ban on thiamethoxam, imidacloprid and clothianidin which is expected to come into force by the end of 2018, covers all outdoor uses in Europe.
The chemical use will however be permitted in permanent greenhouses where exposure to bees is unlikely. The Commission was persuaded by scientific evidence that showed that neonicotinoids not only cause disorientation, fertility reduction and weakens the immune system of many species of bees and other pollinators, but also affect birds and aquatic life like fish and macroinvertebrates.
Despite this threat to bee health and the fact that the African honey bee is proven to be more sensitive to these neonicotinoids than the European one, these pesticides are heavily and widely used in Kenya. Imidacloprid and thiamethoxam for example are approved for use in controlling insect pests in coffee farms, French beans, maize, cotton, wheat, forestry nurseries, roses, tobacco and vegetables.
Currently, there are 41 different products in the market which contain these two active ingredients. The Pests Control Products Board (PCPB) has registered 718 products of which 28% are not approved in Europe because of their potential human or environmental health effects.
Risk To Bees
Considering that many crops grown in the country, especially those important to small-scale farmers, depend on insect pollination for good yields and quality and that these farmers are the majority in the sector, the welfare of bees is therefore highly dependent on them. It will be really helpful if farmers became more aware of the potential toxicity of pesticides available in local agro-vets towards pollinators.
A survey done in 2013 showed that farmers in various parts of the country do not follow pesticide usage advice such as those instructing them to avoid application during morning hours when pollinators are active. This exacerbates the decline in production of crops such as passion fruit, pumpkin, watermelon, okra and strawberries that are wholly dependent on pollinators. The yields and quality of other crops like coffee, avocado, mango and runner beans are also impacted negatively.
Human Health Concerns
With emerging scientific findings suggesting that neonicotinoids pose a health risk to the human nervous system coupled with its contamination of waterways and food, the concern extends far beyond the already significant risk to bees. This is because neonicotinoids are absorbed by the plant internally, meaning we cannot just rinse them off.
Thus the probability that we are exposed to them through the food we are consuming is relatively high. Some studies revealed that nearly 75% of honey produced in the world contains at least one or more of toxic neonicotinoid pesticides. In Kenya, the highest level of thiamethoxam measured in pollen was 0.05 mg/kg, which is 5 times higher than the Maximum Residue Limits (MRL) of 0.01mg/kg.
Given all these risks and the fact that Kenya is food insecure, a ban on neonicotinoids in the country would be an important step. This would allow for further detailed studies to undertaken to determine the extent of the damage that the use of pesticides is having on our environment, our pollinators and our health.
These risk assessments would however depend on several factors including how the regulatory authority, PCPB views the risks to pollinators and other insects, the forthcoming studies on local pollinator populations and also how they are impacted by the currently used neonicotinoids.
Other Control Measures
At the same time, strict measures should be put in place and enforced by regulatory authorities like NEMA, KEPHIS, PCPB and Ministry of Agriculture so that pesticides proven to be toxic to the environment and human health are banned and not made available to farmers.
Other recommendations include advising farmers on environmentally safe methods of applying pesticides and on safe frequencies. Pesticides are persistent and accumulate in the environment and our food – their levels should be monitored regularly.
Beekeepers should be advised to locate their apiaries away from cultivated areas of intensive conventional cropping to minimize honey bee exposure by foraging on contaminated pollen and nectar and carrying pesticides into the food chain. Work on effects of neonicotinoids on the health of the African honey bee and other local species should be done in different locations in the country.
But even as we move to protect the health of our pollinators, what the country should be prioritizing is a shift towards more natural and sustainable farming practices that minimise the use of fertilizers and pesticide and promote and preserve healthy and diverse soil ecosystems.
About Dr. Silke
Dr. Silke Bollmohr is an Environmental Scientist and Managing Director of EcoTrac Consulting. Dr. Silk specializes in management of plant protection products and
other chemicals including aquatic ecotoxicology and risk assessment, water quality and sediment quality, human health, sustainable agriculture strategies and Integrated Pest Management. firstname.lastname@example.org