So I did a little research. And with most environmental problems, there's several causes. One big issue is habitat fragmentation and loss. Because more land is being cleared year after year for crops, bees have to travel further for food or settle for less nutritious food. For example, most farm land in Wisconsin produces either corn or soy. In 2016, Wisconsin had approximately 1.95 million acres of soybean fields and that's up from 1.6 million acres back in 2011. Healthy bee numbers rely on a varied diet, with several different types of species of flowering plants providing pollen and nectar. Monoculture farming does not provide much sustenance for bee colonies.
Now add in the fact that these crops are either genetically modified and/or sprayed heavily. Insecticides known as neonictotinoids are fatal to bees. Crops such as soybeans are routinely sprayed with Imidecloprid which is a neonictotinoid. Pesticides are linked to what is called Colony Collapse Disorder. Bees are contaminated with these chemicals when they are foraging for pollen and nectar. And the pollen and nectar can be contaminated as well. Not only do these chemicals harm the bee but when the bee returns to the hive, it can spread the chemical and contaminate the whole colony. This class of insecticides not only affects bees but other pollinators as well such as birds, butterflies and other beneficial insects.
Roundup Ready corn (a genetically engineered species that is tolerant of certain chemicals like glyphosate) is another crop of concern. According to Linda Reynolds of the Milwaukee County Cooperative Extension, this Roundup Ready corn is killing milkweed because of glyphosate application. Bees and butterflies thrive on milkweed. It is rich in nectar and the Monarch butterfly lays its eggs on the leaves and the leaves are food for the hatching larvae. And most people are aware that Monarch populations in the Americas has declined significantly over the last 20 years. In addition to the decline of milkweed populations, Linda also points out that many plants have been hybridized so much that they no longer have nectaries to produce nectar.
So back to my original question-is there more bee diversity in the city vs. the country?
Well with the recent DIY and growing food movements, I can see how this may be possible in some areas. Urban areas provide a varied diet that has a wider range of flowers and vegetables, thus providing a richer diversity of pollen and nectar. I know in my own neighborhood of Riverwest, most people have small, urban gardens in addition to flowering plants. Container planting is popular too here. Also there is a trend of planting more native species, milkweed being one of them, to attract more pollinators.
So what can we do to help our pollinators?
Plant more flowers and veggies, of course! Try to stick with heirloom varieties of vegetables. And don't forget to plant milkweed! Avoid pesticides at all costs and if you have a birdbath or a constructed pond, make sure it contains clean water. Bees do need to drink water and they carry it back to their hives. I've seen them do it!
If you are in the Great Lakes region, you can visit:
http://xerces.org/pollinator-conservation-resources-us-and-canada/ to give you some ideas. You can also find this info for other regions of the country by clicking on the map of the US.