The study, funded by the German Research Foundation, found that spuds weighed 2.5 times more where 10 per cent of potatoes were infested with the larvae of the potato moth.

A 20 per cent infestation rate still produced a doubled marketable yield with a 50 per cent rate resulting a standard yields.

The researchers believe the growth spurt is due to compounds in the larvae's spit resulting in larger tubers forming.

Larger tubers were only seen in un-infested plants whereas those occupied by moths remained the same size.

Katja Poveda, lead researcher, said: "Initially, I wanted to show how much these pests reduce potato yields, but we actually found they increase the yield."

The positive results have so far only been found in the Columbian Andes potato plant.

Researchers plan to test further varieties in the future.