Phthorimaea operculella is a gelechiid moth belonging to the Gelechiidae family. It is native to America, but has spread all over the world. It affects all types of the Solanaceae plant family, such as tobacco, aubergines, tomatoes, peppers and especially potatoes. Its attacks are very serious because the caterpillar lives inside the potatoes and the damages are revealed when the potatoes are stored in the warehouses.
Morphology and biology
The adult potato tuber moth is a small moth measuring 7 to 9 mm long. Its wings are a grey colour with black spots and frayed edges. The larva is a whitish-pink colour with a brown head. They pupate inside a light-coloured cocoon. The eggs are oval and white to begin with, but later darken.
They prefer to grow in warmer climates where they can produce up to 7 generations each year. The females attack the potatoes at night or late afternoon and have a very short life. They prefer to lay their eggs inside potatoes, but they can also lay them in the stems and on other wild or cultivated Solanaceae.
Phthorimaea operculella larva and pupa
Phthorimaea operculella pupa inside a larval tunnel
LThe larva penetrates the plant and lives as a miner in the leaves and stem. It creates galleries at the base of the buds in potatoes. Inside the potato, the caterpillar excavates superficial galleries at first, and then deeper galleries. At the end of its growth period, it usually abandons the gallery to pupate, although it can also do this inside the potato.
In places with higher temperatures such as warehouses, the cycle is repeated in winter. In colder conditions, for example in fields, it hibernates in the form of a pupa.
Developmental stages of Phthorimaea operculella: A) egg, B) larva, C) pupa y D) adults (female on the left and male on the right). Photos courtesy of CIP
The damage caused in the stem are not very serious. In contrast, the damage caused to potatoes stored in warehouses can be substantial.
The potatoes that have been attacked are easily recognised because the larva excrements can be seen near the buds and in the entry holes of the potato. At first, the excrements are white, but later turn a blackish colour, giving the potatoes a characteristic appearance that reveals the presence of the insect.
Although it has been said that the moth also attacks the stem, the most serious damage is carried out inside the potatoes, when they are piled up in fields or warehouses. This is because the galleries excavated by the larvae are later invaded by different types of fungi and bacteria that cause the potatoes to rot, subsequently losing them.
Detection and monitoring
1 to 2 traps per hectare should be placed at the same height as the crops or on a specific support.
The traps should be placed in spring.
POTATO CROPS IN FIELDS:
For mass trapping, the amount of traps per surface area must be increased, depending on the location and uniformity of the plots. One trap controls a surface area between 500 and 1.000 m2. This means a density of 10 to 20 traps per hectare.
STORED POTATOS IN WAREHOUSES:
The traps should be placed where there is more possibility of finding the potato tuber moth and at specific points of the food production process, where rapid detection of the presence of these insects is important. In warehouses with a smaller quantity of stored produce, it is also convenient to place traps. In places where the moths are most active, traps should be monitored weekly to observe the amount of captured insects. In other areas, every 15 days.
In warehouses, the density of traps is a minimum of 3 traps and a maximum of 9 traps per 1.0002. Enclosures near to the infected area should have traps, as well as the corridors that are connected to this area. If the corridors come out directly from the infected area, they should have 2 traps placed (one in front of the other).
An ECONEX POLILLERO trap, ECONEX WHITE TRIANGULAR without sheets, ECONEX FOLDING WHITE TRIANGULAR WITHOUT SHEETS or an ECONEX DISPOSABLE WHITE TRIANGULAR trap and an ECONEX PHTHORIMAEA OPERCULELLA 2 MG 40 DAYS pheromone diffuser.
Las trampas ECONEX TRIANGULAR BLANCA sin láminas y ECONEX TRIANGULAR BLANCA PLEGABLE SIN LÁMINAS se activan al colocar una ECONEX LÁMINA PARA TRIANGULAR ENV. 1 UD. en la base de las mismas. La lámina está impregnada con un adhesivo sensible a la presión, sin disolventes, en el que los insectos quedan atrapados.
ECONEX PHTHORIMAEA OPERCULELLA 2 MG 40 DAYS pheromone diffuser and packaging of the product
3.61 € (excl. VAT)
ECONEX WHITE TRIANGULAR without sheets
4.20 € (excl. VAT)
ECONEX FOLDING WHITE TRIANGULAR WITHOUT SHEETS
3.57 € (excl. VAT)
ECONEX SHEET FOR TRIANGULAR 1 UNIT PACK
0.84 € (excl. VAT)
5.98 € (excl. VAT)
ECONEX DISPOSABLE WHITE TRIANGULAR
1.84 € (excl. VAT)
Factors that influence the number of traps needed
The pest population, the bordering crops, level of control required, etc….
One important factor is the size of the crops. In small and irregular crops, a greater number of traps are required than in larger and more uniform plots.
Another important factor is the distance between plots that have Phthorimaea operculella. In cases like this, the borders of the plots must be reinforced, so it could be necessary to place up to 20 traps per hectare or even more for mass trapping.