Cactus moth, South american cactus moth, Nopal moth
Cactoblastis cactorum, the cactus moth, South American cactus moth or nopal moth, is native to Argentina, Paraguay, Uruguay and southern Brazil. It is one of five species in the genus Cactoblastis that inhabit South America, where many parasitoids, predators and pathogens control the expansion of the moths' population. This species has been introduced into many areas outside its natural range, including Australia, the Caribbean, and South Africa. In some locations, it has spread uncontrollably and was consequently classified an invasive species. However, in other places such as Australia, it has gained favor for its role in the biological control of cacti from the genus Opuntia, such as prickly pear.
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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Following its introduction into the Caribbean, Cactoblastis cactorum was able to spread across the Atlantic Ocean and throughout the Caribbean through an unknown mix of natural dispersal, intentional and unintentional human transport, and importation on infested livestock fodder. It has been spotted in Saint Kitts, the US Virgin Islands, Haiti, Cuba, the Dominican Republic, the Bahamas, the Cayman Islands, Puerto Rico and Barbados.
It eventually reached the Southeastern United States and was first detected in Florida in 1989. Cactoblastis cactorum likely entered Florida through importation of Opuntia from the Dominican Republic. It is estimated that Cactoblastis is currently expanding its range along both the Gulf and Atlantic coasts at a rate of 100 miles per year, with a constant increase in the rate of colonization along the Gulf Coast. As it spreads, it threatens the population of Opuntia cacti in Florida, in the Atlantic coast up to Charleston, South Carolina, and around the Gulf Coast up to New Orleans.
As the moth moves through the Southeastern United States, it endangers many cactus species and threatens many ecosystems. In Florida, the greatest concern is for the critically endangered semaphore cactus Consolea corallicola. Studies aim to identify the most efficient way to prevent the invasion of Cactoblastis cactorum in the semaphore cactus population. In addition to the semaphore cactus, the arrival of Cactoblastis cactorum to the United States caused concern for the ornamental cactus industry in Arizona, California, Nevada, New Mexico and Texas. Arizona has the largest economic stake in Cactoblastis; the retail value of its cactus industry is around $9.5 million.
Cactoblastis cactorum has spread across the Gulf to Mexico, where it was first discovered on Isla Mujeres, a small island off the northeast coast of the Yucatán Peninsula. It is unknown how the moth migrated to Mexico; speculated means of propagation include winds and hurricanes, unintentional transport by humans, or commercial trade. Cactoblastis cactorum began to attack Opuntia cacti on San Salvador Island in the Bahamas, where Opuntia cacti, especially the prickly pear cactus, are a major food source for the Cyclura iguanas. The decrease in Opuntia cacti population raises concern of severe damage to the iguana population.
In 2020 a study found that C. cactorum is unselective as to which Opuntia species it chooses to feed upon. This may result in even more widespread devastation than previously expected.
Cactoblastis cactorum mating occurs before sunrise. Mates are found by scent rather than sight. Once a female finds a mate, she begins to release sex pheromones that signal to males her readiness. When the male responds, the mating process is initiated.
The initial process of mating begins when the female and male attach themselves at their abdomens. The male passes a sac, known as the "spermatophore", and the female stores the sac in her abdomen's reproductive center. After an incubation period, the female deposits an "egg stick" that contains 30–50 eggs. The eggs are laid on either the tip of the cactus spine, the cactus leaf, the cladode, or the cactus fruit.
Egg sticks that resemble cactus spines develop and hatch in 25–30 days. The gregarious larvae bore into the cactus pad through a single entry hole by chewing through the tough outer cuticle of the cladode. The external damage that results is characterized by yellowed plant tissue with plant fluid ooze and insect frass. The larvae feed inside the cactus and eventually hollow out the cactus pad, consuming everything but the vascular tissues.
Larvae will typically spend two months within the host cactus during the summer, and approximately four months during the winter. Mature larvae exit the cactus pad to form cocoons. They pupate under debris on the ground at the base of the plant. As soon as the moths emerge, they search for a mate, and usually reproduce three to four times within their lifetime. The average longevity is nine days for females and eleven days for males. During this time, the female moth does not eat; she uses all of her energy to travel up to 10 kilometres (6 mi) in search of dense cactus patches for reproduction. The male moth devotes his energy to maximizing his mating opportunities. Males mate between two and five times, and wait two to three days on average between mating events.
