There are a few bad effects, depending on the pesticide, it could cause anyone who eats the crop to get severally ill. That in turn would cause a recall. That could then be bad for the farmer that sprayed the pesticide, as it could get him into legal trouble.
Bees truly are essential to all life on Earth; without them there would be know pollination- with no pollination, there’s no flowers- without producers, the world dies. We need to keep their population safe.