Moth infestations could give bigger potato yields

Posted by Nicole Eckersley on 31st May 2010

Infestation by the larvae of the Guatemalan potato moth (Tecia solanivora) has given researchers from Cornell University a clue to increasing potato yields, according to a new study.

Researchers found that plants where 10% of the potatoes were infested with the larvae produced potatoes weighing 2.5 times more than the potatoes from undamaged plants, even after the infested tubers were removed.  Even a 20% infestation rate still produced a doubled marketable yield. A 50% infestation rate produced the same yield as a normal plant.

Researchers linked the overgrowth of the potatoes to compounds in the larvae’s spit, which causes the Colombian Andes commercial potato plant (Solanum tuberosum) to produce larger tubers. Oddly, the compound only increases the size of a plant’s uninfested tubers – those occupied by the moth larvae remain the same size.

Lead researcher Katja Poveda said that the results of the study, funded by the German Research Foundation, were a surprise. “Initially, I wanted to show how much these pests reduce potato yields, but we actually found they increase the yield,” she said. Currently, farmers spray plants with pesticides every two weeks in an attempt to get rid of the infestations.

The Columbian Andes potato is the only one of seven varieties tested to respond this way so far, although future projects will widen the range of varieties tested.