Source: biologicaldiversity.org/news
These systemic insecticides cause entire plants, including pollen and fruit, to become toxic to pollinators; they are also slow to break down, and thus they build up in the environment.
Here it says the neonicotinoid pesticides are slow to break down. Other sources say their half life is two to three years. That means in 6 years a quarter of what you put on today will still be present,
There will be slightly more than a quarter of what you put on next year added to that.
Half of what you put on in three years on top of that again, …2 years, …last year. In six years the soil load will be twice the application amount and since many of these studies are funded by industry. An industry that wants to minimize problems, my guess is that they took the best case scenario for the half life. OMG.