Been beekeeping 14 years.
Typically, I was getting used to losing 25% of hives over the winter.
A year ago, I had 8 hives. After the winter, I was down to 1, experiencing the most losses I’ve ever had.
now, two loses, I can say were due to carnivorous wasps. The bulk of my loses were probably mite related.
But, perhaps it’s glowbull warming (insert Goebbels icon here).
I just lost a colony this summer. They seemed fine in August. Then last week I noticed a yellow jacket coming out of the hive. So I opened it up and - not a bee in sight. All cells cleaned out.
Was that the wasps? There were not even any dead bees around.
Anyway, on the Roundup question... The plants with Roundup are DEAD. Bees don’t care about dead plants.