The most likely outcome of the change in the ecosystem, considering the reduction in bee population due to an increase in their predator, the dragonfly, would be:
The plant community will become smaller and less diverse.
This outcome results from the fact that many plants depend specifically on bees for pollination. With fewer bees to pollinate them, those plant species may struggle to reproduce, leading to a decrease in their populations. Over time, this can result in a decline in plant diversity, as some species may go extinct or be significantly reduced in number.