Application of the Sterile Insect Technique as part of the eradication program against the cactus moth (Cactoblastis cactorum Berg.) in Mexico

Cactoblastis cactorum Berg has been successfully used as a biological control agent against, Opuntia spp. in countries where these species were considered invasive weeds, such as Australia and South Africa. However, the deliberate introduction of this insect in Caribbean islands turned it into a serious threat to the United States and Mexican cacti species and production, that became more acute by its detection in Florida, USA in 1989, and its spread along the US Gulf coast.

The cactus moth was first detected in Mexico on July 31st 2006 in Isla Mujeres, Quintana Roo, Mexico. This finding started the Cactus Moth Eradication Program in the Yucatan Peninsula, which consisted of activities such as monitoring with pheromone baited traps, sanitation by removing infested plants, training and outreach. As a result of the intensive monitoring carried out in this state, a second outbreak was found the 4th of May 2007 in Isla Contoy, Quintana Roo.

Isla Contoy is a National Protected Area in Mexico, where alternative suppression activities were needed because of the sheltered wild fauna and vegetation. Since sanitation could only be done in the affected zone and chemical control was not an option, the Sterile Insect Technique was the perfect choice.

The sterile moths came initially from Tifton, Georgia and then from Gainesville, Florida where they were raised, sterilized with a Co60 irradiator and dyed with a fluorescent color. The first releases started in March 2008, the results were monitored and the overflooding ratios (irradiated to wild moths) were measured.

Resulting from these actions, the population of cactus moth in the island was gradually reduced, until there were no more findings or catches in the traps. Therefore, in July 2008 the releases ended. After continued monitoring with no detections, by April of 2009 C. cactorum eradication from Mexico was officially declared in the NAPPO Phytosanitary Alert System.