The Chocolate Tree

 

Photo courtesy of Taza Chocolate   The cacao tree is the master of using other organisms for its benefit. It has developed specific and very effective adaptations that allow it to thrive in its environment, most of which involve taking advantage of its neighbors. As mentioned on the Habitat page, cacao trees live under the shade of taller rainforest trees. Theobroma cacao uses this shade to protect its very delicate seeds from sunburn along with wind protection. A more mutualistic relationship occurs between the cacao tree and a few species of midges, the tree's main pollinators.  

The tree rewards the midges by producing cherelles, tiny pods that die before they can grow. These immature pods rot and provide the perfect home for its tiny pollinators. For more information about the cacao's pollination, visit
 http://gears.tucson.ars.ag.gov/book/chap5/cacao.html or see the Reproduction page.

 

 

 

Photo courtesy of cacaoweb.net 

Another important interaction of the cacao tree involves its adaptation for brightly colored pods. These multicolored seed encasements, along with a delicious fleshy pulp inside, attract the attention of monkeys, squirrels and some birds. The tree relies on animals to pick its pods and carry them off for seed dispersal. The bitter taste of the seeds prevents them from being eaten and allows for the perfect placement when they are dropped yards away from the tree.

 

          

 

Although Theobroma cacao is well adapted to exploit its neighbors, it is not exempt from being taken advantage of. There are numerous insects and fungi that infect this tropical tree's roots, leaves and pods. Many caterpillar and larvae species munch on the leaves, while other insects take up residence in rotting pods, along with the midges. Mosquitos, for example, often gather inside the moist, sweet pod in swarms to breed. For more information about mosquito reproduction visit http://bioweb.uwlax.edu/bio203/s2008/otto_lau2/.

 

            Photo courtesy of dropdata.org                 Photo courtesy of dropdata.org

Crinipellis perniciosa , a fungus that causes witches' broom disease is frequently found on the cacao tree since it is specific to the genus Theobroma. Other fungal diseases include Moniliophthora roreri (Frosty Pod Rot) which has very small, powdery spores and a root disease called Ceratocystis fimbriata. On the other hand, the tree does have a mutualistic relationship with other fungi (mychorrizae) like most plants throughout the world. The fungi receive nutrition from the plant's photosynthesis, while the tree uses the fungi for increased absorption of nutrients. Two such fungi are Acaulospora scrobiculata and Glomus etunicatus, a couple of endomycorrhizae. You can learn more about these and other fungi at www.tomvolkfungi.net.

Other insects can also harm the cacao tree. Helopeltis bergrath and Sahlbergella singularis use extensions of the mouth to suck out nutrients from the tree.

Photo courtesy of dropdata.org



A particularly interesting insect that can be beneficial to Theobroma cacao is the black ant, Dolichoderus thoracicus. This ant is a fascinating organism that actually breed mealy  bugs (Cataenococcus hispidus). These ants use the waste materials from the mealy bugs, called honeydew, as a food source and will protect them from any predators they can. In turn, the mealy bugs get obvious protection and a ready food source from the cacao tree. So how does this relationship benefit the tree? The presence of the black ants reduces the number of other insects that are harmful to the tree along with reducing the instance of black pod disease. As for the mealy bugs, they have no harmful effects on the tree. For more information about the black ant-mealy bug relationship visit www.oardc.ohio-state.edu/cocoa/ants.htm.

 

Click here to learn about cacao's classification!

 

 

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