Pacific Views

Bees and Brazil Nuts

The Brazil nut tree is an important species in the Amazon rainforest, both to local animals, and to the humans that harvest them as a profitable cash crop. The seeds are food for the Agouti, a small rodent, whose feeding activities inadvertently reseed future generations and feed other animals.

The pods of the fruit are so hard and tough, that no other animals can open them, and the seeds themselves can't even sprout until removed from their casing. A whole network of creatures rely on stealing seeds tucked away by Agouti. Even after the seeds are gone, discarded empty shells that fill with rain provide miniature ecosystems for the reproduction of small insects and frogs.

And you might think, if you wanted to profit from harvesting Brazil nuts, that it would be far better to grow them in tended orchards where you don't lose so much of your crop to hungry Agouti. But plantations of these trees have been a roaring failure. The Brazil nut tree is a flowering plant, and if the flowers aren't pollinated, they produce no seed pods.

Enter the euglossine bees, also known as orchid bees. Only the females of this species have the strength to pry apart the stamens of the sturdy flower to reach the nectar they hide. Without these specialized insects, no nuts. And you might think, being an enterprising type, that it would be simple enough to set up hives for these bees in an orchard and it would all be good. But unfortunately, that wouldn't work either.

The reason these bees are known as orchid bees is that the males of the species are often the sole pollinators for numerous species of orchids and other flowers. These rare plants that live in the canopy of the forest have evolved elaborate traps to catch the bees, attach their pollen packages, and send them on their way. They offer no nectar, and the bees don't eat the pollen. In fact, the female bees collect all the food for both sexes.

What the males get from the flowers are particular scents that they store in modified leg sacs. Each species has a set of scents they collect, with the orchids they visit generally favored by only a single species of bee. And of course, they wouldn't go to the trouble if there wasn't a payoff, which appears to be sex. The scents collected by the males are used in some way to attract female bees, whether directly or after being modified.

Without the diverse canopy that hosts the orchids and other flowers, these bees tend to die out fairly quickly. Bad news for the Brazil nut, and anyone who wants to eat their seeds.