While some of these losses have been caused by the destructive varroa mite and presumably some result from the use of toxic chemicals to control insect pests with bees affected as accidental damage, what else is affecting colonies is unknown - and this is very disturbing. We need honey bees - and not just for their honey. The honey bee is the major pollinator of many of our food crops and if we lose bees we lose much of our food.
This list, while it is largely based on the Northern Hemisphere, gives some idea of the plants which are pollinated, either partly or entirely - by the honey bee. Don't assume that if the honey bee isn't listed as a primary pollinator - or even not listed as pollinator - for some of the plants mentioned that they don't play a part in pollination in other parts of the world. I've certainly seen honey bees foraging in tomato and eggplant flowers in my garden, for instance, while the list says they are pollinated by bumble bees (which we don't have in Western Australia) and solitary bees (again not found here). So the honey bee - here and probably elsewhere - has moved beyond its traditional food crops into other niches.
While the bulk of the cereal crops (which are wind pollinated) would survive, many fruit and vegetable crops would disappear. Here in Australia we have been protected from pests like the varroa by our very strict quarantine laws - something we've resisted changing despite pressure from overseas - but, even if we end up with the only healthy honey bee population, that won't save the world's food crops. We need the honey bee. If it dies out, we are in serious danger of dying out too.