Poisoned Bees- Main cause???

[220]

@Andersonhoney, thanks for the first hand info, good to hear it didn't set you back.
Still think a hell of a lot more could be learnt from the experience if it was know for sure what was the cause of the deaths.

Like you have said farmers need to do what they need to do but knowing exactly what they can do with the least negative impacts on bees would be hugely beneficial. If it was the roundup that was responsible then it goes against all the scientific evidence, knowing why it did under the circumstances would be very important. If it was the wetter then it would back up your stance that any spraying will kill bees but raises the question of what would have happened if a wetting agent wasn't used. Would the bees have been unharmed, is this what we should be pushing to farmers who do want to look after bees. Spray if you must with a low bee toxicity herbicide but don't use a wetter?
Chemical use in agriculture is a fact of life bee keepers need to live with, at the moment it appears the consensus seems to be you can have bees or you can spray you cant have both. It would be great if there was a way for farmers to continue spraying and have little impact on bees.

[Acebird]

If they didn't need the wetting agent they wouldn't use it.  Chemicals reduce labor so they will continue to be used in a countries that have a high standard of living

[220]

A wetter increases the effectiveness and are cheaper than chemical sprays.
Same results with less chemical, but if it also comes at increased bee deaths the real cost may be higher.
Very little research  seems to have been done on wetters and their effect on bees. Most people who might be interested in doing as little harm to bees as possible would think their use would be a good thing for bees as it allows lower chemical usage rates when in fact the complete opposite may be the case.

[BeeMaster2]

Most wetters are little more than dish soap. They break the water tension so that the chemical sticks to the plant. Other wise it just beads up and rolls off. Problem is that is does the same thing to the bees when they get sprayed or contact the chemical while it is wet. It allow the chemical to enter their body instead of beading up and falling off.
Jim

[220]

interesting paper here on agricultural wetters/surfactants/adjuvants
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4862968/

[Acebird]

I would need a chemist that I trust to tell me what that all means but I will stick to my simple beliefs that chemicals what ever they are used on our food is good for the supplier not the consumer.  It just doesn't make sense to me that putting poisons on my food is good for me in the long run.

[Skeggley]

So still without knowing the OP's location I'm wondering why she/he is so sure they were poisoned?
Due to the poor honey season here in Oz I wonder how their stores were? The area we are in is just coming out of a summer dearth and I've seen similar with one of our colonies.

[threehives]

Thanks for all the replies, I am located in Wagga Wagga, NSW. I am yet to put my finger on the cause. All the colonies had plenty of stored honey and pollen. It was definitely poisoning. Since I found the dead bees, one colony has died, hopefully the rest get through.