In an effort to determine the effect of a major pest on the Colombian Andes commercial potato (Solanum tuberosum), researchers from Cornell University, the University of Goettingen, and the National University of Columbia tested tuber growth in the presence of pest infestation. Expecting that infestation of the tubers by the Guatemalan potato moth larvae (Tecia solanivora) would decrease yields, the researchers were surprised when they found that plant yield actually increased significantly.

When 20% of tubers were infested, the researchers found that the weight of the plant yield doubled.  Even when half of the potatoes were infested, plant yields were similar to those of plants without infestation. However, the infested tubers themselves do not actually increase in size. When a tuber is infested, other tubers in the plant begin growing more than usual. The authors found that the spit of the moth caterpillar is responsible for this unusual growth pattern and are trying to determine the specific compound in the spit that triggers the growth. The researchers hypothesized that the plant undergoes photosynthesis more when a tuber is infected in order to compensate for the loss of the infected tuber.

If the compound that causes this growth is isolated, it could have great implications in agriculture. Selectively administering the compound in tubers would allow farmers to increase their yields greatly, even after removing the infested tuber. The spit of the moth does not create universal growth in potato species, however. Seven species of potatoes were tested, but only Solanum tuberosum responded in this manner. However, this unique growth mechanism could be a common physiological response in many other plants when triggered by their respective compounds.

Discussion Question: What other evolutionary beneficial relationships do you know of that are similar to the relationship between the potato plant and moth larvae?

News Article: http://www.sciencedaily.com/releases/2010/05/100527131704.htm
Journal Article : http://www.esajournals.org/doi/abs/10.1890/09-1726