One of our freinds has had a similar case of bees dieing suddenly, first there were quite a few then they all but a few pegged it.
Poisoning is suspected and samples have already been sent and the inspectors are on their way to investigate in a few days time, we both know the local inspector who is also coming.
No other bee keepers within a five mile radious have reported or been effected, so its an isolated case.
The trouble today especially with some farmers is they are under constant pressure to make a living that they might just be tempted to use very old chemicals that they have kept aside for years.
These items would not be on any inventory if they got them before legislation came into being.
The local inspector says the equipment used by the lab where the samples were sent can detect chemical ellement in their billions which is fine, but I would recommend that sterile containers are used to elliminate any cross contamination of the samples to make a positive detection of the ellements if any.
Also I would have other contents of the hive checked to see if there are any ellements present in the pollen and most developed brood, not just the demised.
Some chemicals can have/take a little longer before having an effect on the daily workings of a colony and could have been present for many days before the die off, hence contamination of other parts and systems within the hive, an accumulation of contamination over a period, leading to the kill off levels.
What about human sewerage farms nearby, these are deadly pathogenic time bombs open to the air we breath and can be smelled for miles when they let go, my freind has one not more than 300 yards from his garden, where his home colony has also been effected.
There are so many man made obstacles today against our wild life which the most delicate of are our first and one of the best early warning signs.
Like in many of these cases where no ellements/compounds have been detected, no so called N,oids nothing, making detection of the reasons very difficult.
I would also opt for multiple lab test results to cross reference the data just to be sure of complacency and inconclusive results through other cross contamination,,,, in this current downturn I have little faith in a system which is in part and parcel by design failing itself and us and the bees.
And to not wanting to be A-pollitical,,,, In this day and age huge corporations like M******o, who make all the chemicals and billions designing and selling these poisons to the general public could easily afford the resorces to iron out most if not all of these finger pointing problems, yet turn a blind eye to proceedings, in favour of vested frankenfood and interest comes to mind.
If you hav'nt yet seen it, seek out a film by biodynamics expert, Mike Porter of NewZealand called,
One Man One Cow One Planet.
La Vita Bella.