A pest once deliberately moved around the world to solve an agricultural problem has become a problem of its own.
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moved → move → own
According to a report by the USDA’s principal scientific research agency ARS, the South American cactus moth was introduced to the Caribbean decades ago to control invasive prickly pear.
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moth → accord → pear
After reaching Florida, it began spreading through the very cactus populations native to the southern United States and Mexico.
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it → reach → States
Now, researchers with the U.S. Department of Agriculture's Agricultural Research Service are working to stop its advance using a biological control method that turns the moth's own reproductive cycle against it.
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that → work → it
According to the report, the story began with prickly pear, a cactus considered an invasive agricultural pest in Australia during the 19th century.
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story → accord → century
The South American cactus moth was introduced there as a biological control agent, helping reduce the spread of the unwanted plants.
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moth → introduce → plants
The same strategy was later used in the Caribbean.
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strategy → use → Caribbean
In 1957, the moth was deliberately introduced to Nevis at the request of the local government to control invasive prickly pear.
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moth → introduce → pear
The moth subsequently spread to neighboring islands and eventually reached the Florida Keys in 1989.
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moth → spread → 1989
From there, it expanded along sections of the Atlantic and Gulf coasts.
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it → expand → coasts
What had once been a useful tool for controlling prickly pear in places where the plant was invasive was now encountering native cactus populations.
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plant → control → populations
A threat to native cactus
According to scientists, the South American cactus moth primarily attacks Opuntia species, commonly known as prickly pear cactus.
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moth → accord → cactus
It can also occasionally affect Nopalea, Cylindropuntia and Consolea species.
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It → affect → species
The damage begins when female moths lay their eggs on the cactus.
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moths → begin → cactus
After hatching, the larvae feed together, boring into cactus pads and tunneling through their interiors.
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larvae → hatch → interiors
As the larvae hollow out the pads, the affected sections can eventually die, weakening or killing the plant.
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sections → hollow → plant
Prickly pear has ecological value beyond its appearance.
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pear → have → appearance
The cacti provide habitat for wildlife and nesting animals, while their root systems can help limit erosion and their dense growth can provide wind protection.
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growth → provide → protection
Some species are also cultivated as specialty food crops in the United States and Mexico.
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species → cultivate → States
Turning sterile moths into a control tool
Researchers are now fighting the invasive moth with a technique known as the sterile insect technique, or SIT.
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Researchers → turn → technique
Entomologist James Carpenter of the ARS Crop Protection and Management Research Unit in Tifton, Georgia, is working with colleagues to mass-produce the moth on an artificial diet.
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Carpenter → work → diet
Male moths are then exposed to radiation that makes them sterile before being released into areas containing wild populations.
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them → expose → populations
The sterile males can still mate with wild females, but the resulting offspring are unable to reproduce.
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offspring → mate → females
Over time, repeated releases can reduce the number of fertile insects in the population.
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releases → repeat → population
The work involves researchers from ARS facilities in Georgia and Florida, other USDA agencies and Florida A&M University.
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work → involve → Georgia
Testing the strategy in the field
The research team is evaluating the approach at three locations: Dauphin Island in Alabama, Okaloosa Island in Florida and St. George Island in Florida.
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team → test → Florida
Each site is being managed differently to help researchers measure the effects of the treatment.
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researchers → manage → treatment
Dauphin Island is receiving sterile moths alongside a sanitation program, while Okaloosa Island is undergoing sanitation alone.
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Island → receive → sanitation
St. George Island serves as an untreated comparison site.
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Island → serve → site
Sanitation involves finding and removing cactus pads containing moth larvae or pupae, as well as eliminating egg sticks.
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Sanitation → involve → sticks
On Dauphin Island, combining sanitation with sterile insect releases has already reduced the cactus moth population to levels that are nearly undetectable, concludes the online report.
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report → combine → levels
The Aporia
