How can we as home gardeners have any positive contributions to bee health?
One answer is to stop using chemical biocides in our own gardens. A biocide is anything that kills off life and includes herbicides, molluscicides (snail killers), fungicides and insecticides. I see that humanity has to find a new model of controlling pests on food crops in particular, that does not involve spraying with chemical killers. This will require innovative thinking.
One successful approach is to cover crops in exclusion netting, which simply stops butterflies or Mediterranean fruit fly from coming into contact with your vegetables or fruit. As consumers we have enormous power at the places where we buy our food. Organic certified food is grown without chemical inputs so this makes a good starting point.
Why would we go so far to help bees? My best answer is that it's not just bees, biocides have unintended consequences throughout the environment because everything living is connected. The most sobering thought here is; eventually we finish up consuming a cocktail of all these biocides as we are at the top of the food chain. But without bees, we face a difficult future.