[veddox]

> The real danger I think is in the decrease of insect population.

That is certainly one of the most important issues. However, habitat loss is even more critical (not only but also because it also decreases insect numbers).

> Is there a study about the effects of decreased pollination?

Pollination and other ecosystem services have been heavily studied in the last decade. Putting precise numbers on it is tricky though, because there are so many context-specific factors that play a role. However, this is one important global study that shows a clear effect of pollination on yield: https://doi.org/10.1126/sciadv.aax0121