Mexico Deploys Sterile Flies to Fight Livestock Screwworm

The Government of Mexico, through the Ministry of Agriculture and Rural Development (SADER), is implementing the Sterile Insect Technique (SIT) to control the cattle screwworm (GBG). Through this program, authorities released 885 million sterile flies between November 2024 and May 2025.

"This technique makes it possible to control pests without harming the environment or affecting beneficial insects," writes SADER in an official statement. This program is part of a comprehensive agricultural health strategy.

The GBG, or Cochliomyia hominivorax, represents a significant threat to the livestock industry due to its ability to infest warm-blooded animals, causing wounds that result in infections, loss of productivity, and even death of livestock. According to the Manual of Standardized Procedures for Epidemiological Surveillance of Cochliomyia hominivorax myiasis in humans, the presence of this pest can generate considerable economic losses to the livestock sector. In response, countries have opted for sustainable methods of control, such as the SIT.

The SIT has been used in successful campaigns against agricultural pests such as the Mediterranean fruit fly (Ceratitis capitata) and various species of fruit flies (Anastrepha spp.). In the case of GBG, its implementation seeks to eradicate the pest without resorting to pesticides or chemicals that could damage the ecosystem or affect beneficial species such as bees, which are essential for pollination and ecological balance.

The National Agri-Food Health, Safety, and Quality Service (SENASICA) is leading the implementation of the program. From Nov. 30, 2024 to May 16, 2025, over 885 million sterile flies have been released. These flies originate in the production plant located in Pacora, Panama, and are transferred to the Dispersion Centers in Tapachula and Tuxtla Gutierrez, Chiapas. There, the insects complete their development before being dispersed by air in strategic areas with presence or risk of infestation.

The technique is based on raising large numbers of male insects, which are fed and sterilized by exposure to ionizing radiation. They are then released into the environment to mate with fertile wild females. Failing to produce viable offspring, the pest insect population is progressively reduced. This biological mechanism requires the constant release of sterile males at densities high enough to outnumber fertile males in the wild.

Sustained application of SIT allows the incidence of the pest to be reduced in each reproductive cycle. The objective is to reach levels that allow long-term eradication or containment, with minimal impact on the environment and without generating biological resistance, a common problem with conventional chemical methods.

The Mexican strategy is in line with international animal health standards and has direct implications for reducing economic losses due to parasitism, increasing livestock productivity and improving animal welfare indicators. Through the program and regional cooperation, SADER expects to consolidate a containment belt against GBG in key areas in the south of the country.