Oxitec medfly cage study in Crete.
Oxitec medfly cage study in Crete.

The Mediterranean fruit fly, or medfly, is an invasive pest that attacks more than 300 different fruits, vegetables and nuts, but is most infamous for the damage it causes in citrus and mango plantations worldwide.

Current control methods rely on insecticides, mass-trapping and the sterile insect technique (SIT), but each method suffers limitations and growers still struggle to keep the pest under control. There’s a clear need for new medfly management tools.

Oxitec, a British biotech company pioneering approaches to tackling dengue fever and damaging agricultural pests, has developed an alternative control tool, which uses genetic technology to overcome some limitations of the SIT. The insects are genetically marked with a fluorescent protein so they are easily monitored in the field, and the male-selecting gene means that the sterilization-by-irradiation step used by the SIT is not needed.

By design, Oxitec medflies will show better performance in the field, in finding and mating with wild female medflies. Like the SIT, Oxitec’s approach is based on mating between released male insects and their wild counterparts, so it is highly specific to the target species, minimizing off-target effects to local ecology.

A recent paper, published in the journal Proceedings of the Royal Society B, describes experiments in which the Oxitec medfly showed strong performance in competing with wild males for female mates. The weekly releases of Oxitec male flies controlled target medfly populations in large greenhouse cages. These experiments, conducted in collaboration with the University of Crete and the University of East Anglia, demonstrate the promise of the Oxitec approach against this devastating pest.

The next step will be field tests in Brazil orchards, in collaboration with the Brazilian fruit fly management specialists Moscamed. The aim of these tests is to demonstrate the effectiveness of Oxitec medfly in controlling wild medfly populations in the field.