Corn Pyral (Ostrinia nubilalis): [Characteristics, Detection, Effects and Treatment]

What is the corn spiral?

One of the best known pests in cereals is popularly known as the corn borer.

With the scientific name Ostrinia nubilalis, it belongs to the group of crambidos and has a special obsession with corn, its favorite food.

Native to Europe, this pest originally infected millet varieties.It is also known by the names of corn borer and corn borer.

How can we identify it?

It is not difficult to recognize this invasive species. Let’s see how to identify the most outstanding characteristics of its morphological appearance and its life behavior.

1. Adults are usually about 2.5 cm long and have prominent, large, robust wings.
2. The female butterflies have a striking yellowish brown color and dark bands of regular presence on the wings. They are also larger than males, darker in color.
3. At least they guarantee between 1-4 generations per year, being able to fully develop in any climate, as long as the temperature is not lower than 15ºC, in a period that goes from May to the following April.
4. The first generation causes the greatest damage to the plant, because it can be cut off when it is still young.
5. Another characteristic is that when they close their wings completely, the final part of the abdomen protrudes, becoming visible.
6. Larvae are up to 2 cm long and their color ranges from light gray to deep pink with dots on each groove or segmentation.
7. The females usually deposit their eggs on the undersides of the leaves of the host plant. They have a yellowish color that makes them visible, but as they grow more whitish, they become transparent to the point that the black head of the larva is not yet mature.
8. The caterpillar manages to break its shell, with skillful bites that it will later apply to the stems, leaves and fruits of cereal crops to feed itself, especially in corn plantations.
9. The parasites then manage to pierce the stems, in the middle and upper part, in order to enter, holes through which the excretions and the remains that remain from the bites will also sprout, which also reach the leaf axils.
10. They eat upwards, until they go down to the neck of the root.
11. Another curious fact is that a single larva can damage several plants, because it is capable of moving quickly after completing its mission.
12. The most visible leaves will also end up being ruined or broken, but this damage that usually occurs in the upper part of the plantation will not necessarily ruin the harvest, although if they touch the cob it will make things drastically worse.
13. These lesions can also lead to the appearance of fungal pathogens such as Fusarium, so the advance of these Ostrinia nubilalis must be avoided at all costs.

What plants does corn pyral affect?

It is the caterpillars of this species that cause damage to corn stalks and ears, because they are expert tunnel diggers. They also very much like to invade millet to act in the same way.

In the worst case, if this caterpillar is not exterminated, the plant can die in a short time, because it runs out of nutrients.

The Sesamia nonagriodes variety is a specialist in giving crops of sorghum and sugar cane, but the Ostrinia nubilalis ameas corn, attacks crops of peppers, broad beans, potatoes, among others.

How to combat the corn pyral?

Biological control methods are excellent, because they do not harm the environment or poison crops.

predators

One of the favorites is the fungus Beauveria bassiana, but also to control this plague are the parasitoid hymenoperas, belonging to the genus Trichogramma and the protozoan Nosema pyrausta, which we must introduce in the plantation following the instructions of specialists.

The Trichogramma brassicae wasp is the queen of predators of all corn pests, not only this butterfly, which is especially harmful in its life as a caterpillar, so it is highly recommended to introduce it into the crop so that it can fully do its job.

There is a technique that induces the parasitization process of this wasp when it is in the pupal stage. A piece of cardboard is found and the pupae of the Trichogramma brassicae are glued, using good glue.

Arabic gum is ideal for this trap.When the Corn Pyral takes flight towards its target, the parasitoid is then released into the plantation twice in a period of about 10 days.

The wasp eggs will hatch and begin to parasitize the borer eggs, with a high success rate of over 75% of all intruders.

Corn hybrids with insecticidal toxin

Similarly, biologically manipulated hybrids have been obtained in the laboratory, called GMOs, capable of containing an insecticide toxin after the application of a gene that comes from the bacterium Bacillus thuringensis (BT).

This genetic manipulation has been successful in combating the corn borer, as well as other worms that also attack the stems and roots of this star cereal that is widely consumed throughout the world, especially in the American continent.

It is also necessary to be attentive to the attacks of other very frequent corn pests, such as: thrips, beetles, grasshoppers and fleas, which appear during the hottest days, in countries with a hot climate.

Destruction of corn crop stubble

But without a doubt, it cannot be postponed that all the remains or stubble of the corn contaminated by the plague must be buried or eliminated by introducing it into a deep cellar, where the parasites that still survive are also isolated.

What are the best products to eliminate corn pyral?

Although it should be avoided at all costs, chemical control is effective when applied to the first generations of Ostrinia nubilalis.

A treatment with chlorpyrifos or some other substance authorized by the bodies responsible for the agricultural sector is always highly effective, always following the indications expressly stipulated in the product’s prospectuses.