There are certain olive varieties that are pollinated ONLY by certain wasps. Lose those wasps = no more of those olives.

And Giok mentions the icheumon. Nothing more seemingly cruel and exploitative in the universe (although it is a strategy that seems to work and is therefore "good" in the survival of the fittest sense). The mother wasp lays an egg in a caterpillar (using the ovipisitor, bravo for that fun word Giok). When the egg hatches, the "worm within a worm" knows instinctively to eat only the fatty tissues inside the skin of the caterpillar and leave the vital organs untouched. It thus lives inside its dinner keeping it barely alive just long enough to reach its own pupation. Ugh. But wow.