Without them, there would be no producers and, ultimately, no ecosystem. If all producers were eliminated, herbivores would not be able to obtain its energy, causing their death. This affects consumers because they rely on herbivores. Without producers there would be virtually no energy to transfer to higher trophic levels, causing ecosystem breakdown. If all insects were eliminated there would be no pollution (bees, butterflies, etc.). Insects are a key factor in plant survival and without them these producers could become extinct. Without producers, the entire ecosystem can die out because there is no energy transmitted to the next level. A balanced ecosystem cannot exist if it were composed only of producers and decomposers because decomposers need consumers to get rid of their waste and recycle the matter into the soil for producers to use. Furthermore, there are no consumers who would eat the producers, so this would not be balanced