Pesticides, from the Latin pestis “contagious disease” and caedere “to kill, exterminate”, are synthetic products whose function is to eliminate living beings potentially harmful to the survival and productivity of plants. Included are all biocidal products such as fungicides, herbicides, etc., often referred to more good- naturedly as plant protection or phytopharmaceutical products. However, we often hear that the agricultural and domestic use of pesticides affects in a more or less direct way our life and damage bees and useful insects causing their death and extinction, but how widespread is the problem? What solutions exist?
History of a poisoning
The first proven case of poisoning took place in 1881 in the United States following the use of copper arsenates in an orchard. A few years later the problem exploded in Italy, coinciding with the intense campaign against Dacus oleae, the olive fly, by means of poisoned bait based on arsenates. In 1906 Antonio Berlese, one of the major Italian entomologists, brought to the attention of the general public not only the huge bee slaughter but also the risk of disturbing the existing balance . Controversy broke out in the agricultural world . Among the many things that emerged in that diatribe is worth remembering the reasonableness and relevance of a proposal with which the olive grower James Auget in 1907 put an end to the issue (LIII: 586-590):
“…think of our bees and so many other useful insects whose destruction would be a disaster for agriculture! Distinguished experimenters, place simple hives of bees near the olive groves you are treating: study the effects of your mixture on them and if you recognize it as harmless, then fine, but if it is deadly, stop: otherwise you will be like the bear in the fable, who to free a sleeper from the fly that was bothering him, crushed his head”.
With the advent of the 1900’s the development of new pesticides went hand in hand with the chemical research in the war field. In fact, the studies of the German Fritz Haber, father of chemical weapons used in world conflicts, paved the way for the industrial production of insecticides. For example, phosgene, a toxic gas discovered by Haber and used in the First World War, is still used as a compound in some insecticides; this compound is the sad protagonist of one of the most serious humanitarian and environmental disasters in history: in 1985 in an industrial pesticide plant in the city of Bhotal, India, there was a release of 42 tons of isocyanate, produced by phosgene, polluting the surrounding environment until today.
With the “Green Revolution” , a period between the forties and the seventies interested by an increase in agricultural production, many chemical products , such as organochlorines, organophosphates, DDT and herbicides, were widely used showing only later their dramatic effects on humans and the environment.
Giving bees a voice
Now we know the danger of many pesticides and the effect they have on pollinators and therefore on biodiversity . Many pesticides have been replaced with more modern products with less toxicity for humans, but no less harmful for pollinating insects. In fact, the use of pesticides has decreased worldwide but, in the last 10 years, their impact on pollinators has increased. Only recently has the European Union focused attention on the damage that pesticides cause in some biological processes at the heart of biodiversity, removing from the market some products that had exhausted pollinator populations: it is in 2018 that the EU placed a ban on the use of three nicotinoids , imidacloprid, clothianidin and thiamethoxam, which are lethal to bees . This decision bodes well for the future of beneficial insects, but there is still a long way to go; if the obvious lethal effects of some pesticides have been buffered, we must now consider the chronic and sub-lethal effects caused by some active ingredients. Pesticides that are considered less harmful have the ability to weaken and compromise the affected bee family. Many , in fact,
cause the premature death of adult bees , weakening their immune defenses ; others , specifically microencapsulated and aerosol pesticides, can adhere to the bee’s hair and then , mingling with the pollen, enter the hive poisoning the queen and newborns and compromising the entire family.
What to do?
In the safeguard of pollinators everyone must do his part; the collaboration between beekeepers, veterinarians, farmers and producers of pesticides is essential. The farmer must make a correct use of pesticides, using them only when necessary, not during flowering, possibly in the evening and in the absence of wind, to avoid the drift of aerial treatments; moreover, he can use them only when necessary. also, he can increase natural pest defense by increasing biodiversity in his plot. The beekeeper can maintain a healthy hive by reducing cofactors of die-offs, properly positioning the apiary, and eliminating potentially poisoned stocks. Ultimately, manufacturing companies must strive to produce low-toxicity pesticides and also take responsibility for the postmarket phase of the pesticide life cycle.