Grain Moth: A Silent Threat to Corn Stores

The grain moth (Sitotroga cerealella) is a pest feared by those who store and trade grains such as wheat, rice, corn, barley and others, especially due to the damage it can cause during storage. This pest attacks grains in their larval and adult stages, generating significant losses, particularly when control is more difficult, as occurs in storage facilities. The infestation can result in a decrease in both the weight and quality of the grains, directly impacting the value of the stored product.

In the case of corn, a 2016 study conducted by the Minas Gerais Research Support Foundation (Fapemig) and the Brazilian Agricultural Research Corporation (Embrapa) showed that the pest can cause a loss of up to 17% of the grain's weight in a period of 70 days. This problem is aggravated in the storage environment, where humidity and temperature create ideal conditions for the insect to spread.

If left uncontrolled, the infestation could seriously compromise production, causing major losses, especially considering that Brazil is the world's third largest corn producer, with a forecast harvest of 298,41 million tons in the 2023/2024 harvest, the second largest in history, according to the National Supply Company (Conab).

During the larval stage, the larvae penetrate the grains and feed on their interior, causing damage that is initially invisible, which makes early detection difficult. In the adult stage, the attack is limited to the surface, since the insect cannot penetrate the internal structure of the grain.

The life cycle of the grain moth lasts 4 to 5 weeks, when temperature conditions (around 30°C) and relative humidity (75%) are favorable. Females can lay up to 100 eggs on grains, both in the field and in storage. The larvae, which do not move, develop inside the grains, as do the pupae, which makes the infestation difficult to control. Adults have a lifespan of up to seven days, but in this short period, they are capable of perpetuating the cycle of damage.

Therefore, effective control of the grain moth during storage is crucial to avoid losses in grain quality and quantity, ensuring that agricultural production does not suffer negative impacts until the time of commercialization.

Prevention and combat with recommended products

The best way to avoid losses in grain storage is to prevent infestation by the grain moth. Fábio Kagi, Regulatory Affairs Manager at the National Union of Plant Protection Products Industry (Sindiveg), emphasizes that there are effective preventive measures, such as the application of recommended insecticides, as long as the instructions on the label are followed, so as not to compromise the quality of the stored grains.

"Prevention is crucial to stop the infestation from starting. Cleaning and sanitizing silos and other storage areas must be carried out carefully, removing any residue or pest infestation. This process can be complemented by washing with high-pressure water and the use of long-lasting insecticides," explains Kagi.

If the grain moth is already detected in the grain storage, Kagi recommends the use of fumigants, which release gases that are lethal to the insects. To ensure the effectiveness of the treatment, it is essential that the grains are completely sealed in the storage location, with a minimum exposure period of seven days, according to the dosage indicated by the manufacturer.

"Fumigants are highly effective, as they act quickly, leave no residue after the gas dissipates and have great penetration capacity, reaching even the insects inside the grains", concludes Kagi.