story to find out more.
Larvae of the invasive cactus
moth can attack all species of prickly pear cacti in North America and can
completely destroy a cactus plant. Below, entomologist Colothdian Tate examines
a prickly pear cactus pad infested with the moth's larvae. The insects feed
inside the pad, hollowing it out. Click the images for more information
Protecting the Prickly Pear Cactus in Its Native
Habitat By Sharon Durham September 1, 2006
Scientists with the Agricultural Research Service (ARS) in Georgia and Florida are working to
control a moth that is threatening an important cactus that is native to the
southern United States and Mexico.
Ironically, the South American cactus moth was used to control the
spread of the same cactus species in Australia in the 1800s. The prickly pear
cactus, as the species is called, is not native to Australia but was an
invasive pest in that country.
Then, in 1957, the moth was introduced to the island of Nevis in the
West Indies, by government request, to control the same cactus, which was also
an invasive species on that Caribbean island. Eventually, the cactus moth
spread to surrounding islands, landing in the Florida Keys in 1989. Since then,
the moth has moved along both Atlantic and Gulf coasts and now threatens the
prickly pear cactus in its native habitat in the southern United States and
Mexico, where it is grown as a specialty food crop.
Carpenter, in the ARS
Protection and Management Research Unit at Tifton, Ga., has been studying
the use of the sterile insect technique (SIT) to control the cactus moth in the
United States. Carpenter and cooperators are mass-rearing the moth on an
artificial diet, irradiating male moths to induce sterility and then releasing
the males to mate with wild female moths. Using this approach, the resulting
offspring are infertile, thus reducing the target insect population.
Carpenter is working with entomologist
Hight at the ARS
for Medical, Agricultural and Veterinary Entomology in Gainesville, Fla.,
colleagues at other U.S. Department of
Agriculture agencies, and researchers at Florida A&M University.
The SIT trial evaluation involves three sites: Dauphin Island, Ala.;
Okaloosa Island, Fla.; and St. George Island, Fla. Dauphin Island is receiving
sterile insects and undergoing a sanitation procedure. Okaloosa Island is only
being sanitized, and St. George Island is being left unchanged.
Sanitation involves the removal of cactus pads infested with moth
larvae and pupae, and removal of egg sticks. The combination of SIT and
sanitation has been very successful in reducing the cactus moth population on
Dauphin Island to near non-detectable levels.
about the research in the September 2006 issue of Agricultural Research
ARS is the USDAs principal scientific research agency.