Which organisms cannot complete their life cycles without mutual interaction?

Moths deposit eggs in the locule of the Yucca plant’s ovary, and the flower, in turn, gets pollinated by the moth. The larvae of the moth depend on the seeds developing in the flower for their life cycle completion. Without this interaction, yucca plants cannot reproduce (as they depend entirely on the moths for pollination), and yucca moth larvae would have no food source and a place to develop.