Yes the weed killer Roundup that works great for killing weeds is also very effective at killing bees.
There was a study that showed that Roundup Weed Killer will kill bees and I gave it a try myself because I have some Roundup anyway.
I sprayed some bees with Roundup and they died within about 2 minutes of being sprayed with it as first they dropped to the ground and couldn't move and then eventually they died.
So yes Roundup in my own personal experience kills bees however I haven't tried it on honeybees and it's been said that honeybees have some sort of resistance to the Roundup.
But I've never tried to kill honey bees with it.
Still Roundup is expensive to kill bees as there are cheaper ways to kill bees but if you have some roundup it's a good thing to use to kill bees.