According to the USDA
“During the past 30-plus years, our nation’s pollinator populations have suffered serious losses due to invasive pests and diseases, such as mites and viral and fungal pathogens, exposure to pesticides and other chemicals, loss of habitat, loss of species and genetic diversity, and changing climate.”
While making a study on Pansies in France, scientist determined that the plants were self pollinating at a 27% greater rate than 30 years ago. With less insects available because of environment factors related to chemicals, climate change and farming methods. This might seem like a good deal If we don’t have enough pollinating insects left then the ability of the plant to pollinate itself would be a good deal.
The problem is that without pollen from different flowers, the ability to adapt to varying conditions is limited. Our rapidly changing climate means that we need plants that can carry on with the genes that enable them to survive. This comes from the strongest surviving plants and if they can’t transfer this through pollinators, then the change of climate can be devastating.
Some plants, like corn and wheat, don’t have to have pollinators although insects do provide some advantage. The wind will transfer enough pollen to cross pollinate. This is why, when crossing different varieties to make hybrids for specific traits, they cut off the male tassels from the top of one variety and leave them on a neighboring plant so that they cross pollinate. The result is a new variety that has new traits.
The disadvantage is that you have a plant that doesn't have a natural resistance to disease, damaging insects and extreme weather conditions. Even more important, even though modern hybrids may yield more, the nutrient content is far less while the starch content has increased creating the perfect storm for human weight increases.