Blasted Cactoblastis!

Monique R. wrote in to point out this recent posting in the US Federal Register regarding the South American cactus moth (Cactoblastis cactorum). The USDA has just opened up a public comment period soliciting opinions about an effort to protect the central and western parts of the USA from the negative impact that cactus moths can have on prickly pear cacti (Opuntia spp.) and their cactus relatives (Consolea spp., Cylindropuntia spp., Nopalea spp.). Along with a control program where sterile cactus moths will be released into the wild, the USDA is proposing a four-state quarantine zone (Alabama, Florida, Georgia, and South Carolina) from which interstate movement of the cactus genera listed above would be prohibited. Anyone interested in commenting on this issue can do so up until April 11, 2008.

Cacto Blasters

The San Antonio Express-News is reporting that concerned scientists have put out an alert asking Texas landowners to keep a lookout for the invasive cactus moth (Cactoblastis cactorum) whose arrival in Texas is apparently imminent. The moth, which originates from South America, is a threat to native prickly-pear cacti (Opuntia spp.), and in fact has been used as a biological control in other parts of the world where prickly-pear cacti are considered invasive. Cactus moths were discovered in the U.S. in the late 1980s, and have been spreading both from Florida westward and from Mexico northward. If you're in Texas and you think you've spotted the moths or the caterpillars of this species, you should contact Texas Cooperative Extension (I can't find a related webpage - more information can be found here (.pdf), or call Barron Rector at 979-845-2755).

Moth Rah

ARS News is reporting that scientists may have found a better way to control the cactus moth (Cactoblastis cactorum), a South American insect that preys upon various species of prickly pear cacti (Opuntia spp.).

While there has been some success with releasing sterile male moths into wild populations (sterile insect technique, or SIT), irradiating the males to the point of sterility also left them lazy and less likely to compete with non-sterile males for a mate. Results have shown that dosing the moths with a lower level of radiation gave scientists what they needed: male moths with reduced fertility, rather than sterility, that are much more interested in finding a mate and produce sterile offspring. Field tests for this technique are currently going forward on an island in Alabama, the outermost edge of the moth invasion, which has gradually been spreading from South America up into U.S. territory.

Interested readers may also want to check out previous ISW posts about the cactus moth.

Cacti Attacked

Scientists are concerned that the cactus moth (Cactoblastis cactorum), which dines on virtually any species of prickly pear (Opuntia spp.), is spreading north and west through North America. According to this article from the Arizona Daily Star, the moth, which is native to South America, could be making its way to Arizona and Mexico, where prickly pear cactus is a significant part of the desert ecosystem and also an important agricultual crop. The cactus moth is actually considered one of the first successful biological controls, having been introduced to Australia in the mid-20th century to combat invasive patches of prickly pear cactus. It is now also a pest of native cacti in that country.