Another control approach under investigation for "Aedes aegypti" uses a strain that is genetically modified to require the antibiotic tetracycline to develop beyond the larval stage. Modified males develop normally in a nursery while they are supplied with this chemical and can be released into the wild. However, their subsequent offspring will lack tetracycline in the wild and never mature. Field trials were conducted in the Cayman Islands, Malaysia and Brazil to control the mosquitoes that cause dengue fever. In April 2014, Brazil's National Technical Commission for Biosecurity approved the commercial release of the modified mosquito. The FDA is the lead agency for regulating genetically-engineered mosquitoes in the United States.