Phthorimaea operculella belongs to the Gelechiidae family which is native to America and has spread all over the world. It affects all types of Solanaceae plants 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 warehouses.
MORPHOLOGY AND BIOLOGY
The adult potato tuber moth is a small butterfly 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 a white colour that 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 and have a very short life. They prefer to lay their eggs inside potatoes, but they can also lay them in the stems and other wild or cultivated Solanaceae.
The 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 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 as a pupa.
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 homogeneity 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, as well as in specific phases of the food production process in which a fast detection of the insects’ presence 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 1.000 m2. Enclosures near to the infected area should have traps, as well as the corridors that are connected to this area. If the corridors come from the infected area, they should have 2 traps (one in front of the other).
A trap ECONEX POLILLERO (Code: TA001), ECONEX WHITE TRIANGULAR without sheets (Code: TA118) or ECONEX DISPOSABLE WHITE TRIANGULAR (Code: TA242) and a pheromone diffuser ECONEX PHTHORIMAEA OPERCULELLA 2 MG 40 DAYS.
The trap ECONEX WHITE TRIANGULAR without sheets is activated by placing an ECONEX SHEET FOR TRIANGULAR (Code: TA248) on its base. The sheet is impregnated with a pressure-sensitive adhesive, without solvents, in which the insects are trapped. The trap ECONEX DISPOSABLE WHITE TRIANGULAR is coated on its inner face with a layer of contact adhesive, solvent free, for the retention of the insects.
Both traps stand out above all for their simplicity of use, and will be operative until pheromone depletion or saturation of the sheet or adhesive surface. The pheromone diffuser is placed inside the trap on the sheet or adhesive surface.
PERIOD OF USE
To achieve good control of Phthorimaea operculella it is advisable to combine two methods: detection and monitoring; and mass trapping. In spring, 1 to 2 traps per hectare should be placed for the detection of the pest and observation of its population levels. With tolerance thresholds established in each area, the moment to adopt control measures, in this case mass trapping, can later be defined.
The tolerance threshold for Phthorimaea operculella is very low and varies depending on the area. In general, it is approximately 3 captures per trap and per week. For mass trapping, traps should be placed throughout the plots.
The damages caused in the stem are not very serious. On the contrary, damages to the potatoes that are stored in warehouses can be very important.
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 to 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.
If specialists or farmers use the traps and pheromones correctly, as previously described, especially during the early stages when adults of the first generation appear, this monitoring system is very effective. A very low level of damage, mainly on organic land, has been demonstrated. A level of control of more than 95% is very common, especially in large areas of crops.
A limiting factor of this system is the presence of small plots surrounded by others that have a high level of infestation of Phthorimaea operculella.
Despite some important basic rules for an effective monitoring of Phthorimaea operculella, every farmer or specialist has to find their own system of control to achieve it. They can experiment with this system, even establishing their own tolerance thresholds.
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.
Corrugated cardboard box of 3.000 units (150 packs of 20 units)
Box size: 0.60×0.40×0.35 m (length x width x height)
Box weight: 9.8 kg.
No. of boxes per pallet: 20.
Pallet size: 1.20×0.80×1.90 m (length x width x height).
Pallet weight: 203 kg.
ECONEX WEB RESOURCES
Section of the ECONEX corporate website that allows you access to online information about ECONEX solutions for the biocontrol of other relevant agricultural and forest pests.
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