Biology

Invasive species (IV): the Guatemalan potato moth

Last year alarms went off in Galicia when the presence of the Guatemalan potato moth ( Tecia solanivora Povolný) was detected , a pest that devours potato crops until they are unusable for human consumption and that to date has not stopped expanding. A new invasive species for the Iberian Peninsula.

The Tecia solanivora moth was discovered in Guatemala in 1973. It is a lepidopteran belonging to the Gelechiidae family and that feeds exclusively on the potato ( Solanum tuberosum ), which is also native to South America.

Biology of the Guatemalan Potato Moth

the Guatemalan potato moth
the Guatemalan potato moth

The larvae of this species develop inside the tubers, in which they excavate galleries and partially or totally devour. Upon reaching maturity, the larvae leave the potato and form a pupa a few centimeters below the surface, from which the adult individual emerges.

The adults can travel several tens of kilometers to find another potato plant, at which point they lay their eggs on the stem and the larvae descend to the tubers. The moths are brown in color, with nothing to distinguish them with the naked eye from another species of moth, and they are approximately 1cm in size.

There is another species of moth that feeds on the potato plant and has a global distribution, Phthorimaea operculella . This species also feeds on the tobacco plant (which belongs to the same family as the potato, the nightshades). P. operculella has a size and appearance similar to Tecia solanivora , but there is a fundamental difference in its life cycle, which is that P. operculella feeds on the leaves and stems of plants, while the Guatemalan moth does so exclusively on the tubers. Because of this it is difficult to detect the presence of the pest until the harvest is done and the potatoes are inspected, since the leaves of the plants do not show symptoms of the pest.

Many farmers are surprised by the alarm generated by the Guatemalan moth, stating that it had been present in their crops for decades, when it was really P. operculella the species that has been in our country for a long time. The damage caused by the Guatemalan moth is much more serious, destroying entire crops.

Pest status

In the decades after its discovery, the presence of Tecia solanivora was detected in different countries of South America, arriving in Mexico in 2010. In Spain it has been present since 1999, in the archipelago of the Canary Islands. There is currently a presence of the moth in Tenerife, Gran Canaria, La Gomera, El Hierro and La Palma.

The leap to the peninsula was made in 2015 , when it was introduced in Galicia through a shipment of potatoes from the Canaries. Currently it has spread to the north of the provinces of Lugo and La Coruña, also reaching the western part of Asturias. Despite the fact that the damage produced is not serious for now, it is worrisome that it could spread to those towns where potatoes are grown for trade, since in Galicia it is a fairly widespread crop. It has not been detected in any other European country.

The only existing measure for now to control this pest is quarantine in the areas where Tecia solanivora is present and the destruction of the affected crops. The Xunta de Galicia launched at the beginning of this year a protocol for the prohibition of planting potatoes in 31 municipalities where the Guatemalan moth has been detected. In addition, all potato crops will be collected and subsequently destroyed. Special traps have been placed in potato crops in border areas to preventively detect the presence of adults.

Despite the success of the measures, since this species feeds exclusively on the potato plant and through a quarantine it will be possible to end the moth population present in Galicia, there have been numerous complaints due to the delay with which these measures were taken.

Thus, the farmers maintain that it would have been logical to carry out the ban before the beginning of the growing season, thus avoiding destroying the harvest and being able to have planted another species instead of potatoes. In any case, it is expected that the measures taken will be able to stop the expansion of the Guatemalan moth throughout the rest of the Iberian Peninsula and that an adequate control of potato imports will prevent its proliferation in Europe.

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