Aphids and Their Symbiotic Bacteria Buchnera, Essay Example

Aphids are a form of insect or pest that is capable of causing major damage to platns and crops within nature and the agriculture industry.  “They feed on plants by piercing them with syringe-like mouth parts and sucking the sap out of the phloem, resulting in a diet that is rich in carbohydrates and deficient in amino acids” (Baumann par. 1).  Because these amino acids are essential to the aphid, it must receive the nutrients from another source, which comes from the bacterial symbiont Buchnera aphidicola that lives within the aphid’s body.  “The bacteria are transmitted vertically via the aphid ovary, and the association is obligate for both partners: Bacteria-free aphids grow poorly and produce few or no offspring, and Buchnera are both unknown apart from aphids and apparently unculturable” (Douglas 17).  Therefore, the relationship between these two organisms is required by both to survive; whereas, neither would exist without the other.

This relationship is very special within both organisms.  Many researchers believe that this interaction of the two partners dates back 150 to 250 million years and both have become so dependent on each other that under natural conditions they cannot exist without each other (Baumann par. 1).  Clinical research has shown that because aphids feed solely on plants that do not have the essential amino acids, they must come from the Buchnera bacteria.  This is verified from Baumann where the research showed that “if an antibiotic that kills bacteria is added to the medium, the aphids fail to grow and reproduce” (par. 3).  Therefore, it is clear that the aphids would die without the existence of the Buchnera, and the Buchnera would likewise not exist without the presence of their symbiont host.

While the Buchnera provides essential amino acids for the aphid, it also receives energy, carbon and other important necessary nutrients required for its survival.  One such nutrient is the amino acid, glutamine, which is very abundant in the phloem.  “It was shown that glutamine is ingested by the aphid and transported to the bacteriocytes cells in which the symbionts are housed” (Baumann par. 4).  As the bacteriocytes take in the glutamine, they convert it to glutamic acid, that the symbiont uses to convert into the other essential amino acids required by the host (Baumann par. 4).  Through this cycle of shared amino acids, both organisms are able to feed off of one another, which is a require relationship that must exist for each to survive.

References

Baumann, Paul, Angela E. Douglas, and Nancy A. Moran. “Buchnera Aphid Symbiosis.” Buchnea Aphid Symbiosis. Aug. 2003. Web. 22 Oct. 2009. <http://web.uconn.edu/mcbstaff/graf/BuAp/Baphidsym.htm>.

Douglas, A. E. “Nutritional interactions in insect-microbial symbioses: aphids and their symbiotic bacteria Buchnera.” Annual Review of Entomology 43 (1998): 17-37.

“Symbiosis in Animals.” The University of York. Web. 22 Oct. 2009. <http://www.york.ac.uk/depts/biol/units/symbiosis/intra-symbiosis.html>.