Stiling suggests that this may be an effective method of reducing damage to Mexican Opuntia plantations, should C. In Florida Opuntia plants were protected by cages as soon as C. However, cages prevent cross-pollination and are subject to toppling over in the tropical storms and hurricanes that frequent South Florida. When the cages topple they can knock over and kill the cacti inside.
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Introduction Back to Top The cactus moth, Cactoblastis cactorum Berg Lepidoptera: Pyralidae arrived in in the Florida Keys, and this invasive species has become a serious threat to the diversity and abundance of Opuntia cactus in North America Zimmermann et al.
The spread of this moth raises the following major concerns: 1 potential harm to rare opuntioid species prickly pear and related cacti; members of the subfamily Opuntioideae: Cactaceae , 2 the endangerment of wild opuntioids in the southwestern United States and Mexico and consequent effects on entire desert ecosystems Perez-Sandi , Soberon et al.
Figure 1. Adult cactus moth, Cactoblastis cactorum Berg. Photograph by D. Habeck and F. Bennett, University of Florida. The effort was highly successful. Later, the cactus moth was introduced into Hawaii, India, South Africa, and a few Caribbean islands for this same purpose. In early , the cactus moth was found and quickly eradicated in Mujeres, Mexico about 10 miles offshore from Cancun LSU Cactoblastis cactorus has been introduced multiple times to Florida Marisco et al.
Based on genetic analyses, existing populations probably were likely founded from the introduced Caribbean moth populations Marisco et al. Atlantic and Gulf coasts. Cactoblastis cactorum spreads more quickly along the coasts, but inland spread is occurring.
Please Help! We would like to hear from you if you know of infestations in your area or if you know of the location of Opuntia cactus stands that we could check, particularly if the sites are inland or in front of the leading edge. Please contact: Dr. Stephen Hight , Phone: x Description Back to Top The wing span of the adults ranges from 22 mm to 35 mm.
The forewings are grayish-brown, but whiter toward the costal margin. Distinct black antemedial and subterminal lines are present. Hindwings are white with some gray terminally. Adults of the subfamily Phycitinae often appear very similar to one another and are not identified easily because scales of specimens usually are rubbed off; however, genitalia can provide positive identification Heinrich The larvae of Cactoblastis cactorum are bright orangish-red with large dark spots forming transverse bands.
Mature larvae are 25 mm to 30 mm long. Figure 2. Larvae of cactus moth, Cactoblastis cactorum Berg. Photograph by Christine Miller , University of Florida.
Larvae gregarious, reddish or bluish-purple, feeding in cladodes pads. Larvae solitary, not reddish or bluish-purple, feeding in or on cladodes. Larvae orangish-red with conspicuous dark spots forming transverse bands. Larvae dirty-white to bluish-purple with smaller dark spots not forming transverse bands. Melitara prodenialis Walker 3. Larvae dirty-white, without spots. Larvae dark. Larvae feeding singly in buds or fruit only. Larvae feeding singly on dead tissue but most often feeding on coccids.
Laetilia coccidivora J. Comstock Biology Back to Top The female Cactoblastis cactorum lays her eggs in the form of a chain, the first egg is attached to the end of a spine or spicule, and succeeding eggs average 75, and up to or more are stacked coin-like to form an egg-stick.
On eclosion, the larvae crawl from the egg-stick onto the cladode or pad and burrow into it, usually within a few centimeters of the oviposition site. The larvae feed gregariously moving from cladode to cladode as the food supply is exhausted. During feeding the frass is pushed out of the pad and forms a noticeable heap. Fully developed larvae usually leave the plant and spin white cocoons in the leaf litter, in crevices in the bark of nearby trees, or in similar protected niches.
Pupation occasionally occurs in the cladode. The moth emerges, and the cycle is repeated. The length of the life cycle in Florida is unknown but probably shorter than in Queensland, Australia, where there are two generations per year Dodd Figure 3. Egg stick of the cactus moth, Cactoblastis cactorum Berg , on cactus pad. Females show clear egg-laying preferences, selecting Opuntia engelmannii varieties linguiformis and engelmannii over other opuntiods Jezorek et al.
Interestingly, female egg-laying preferences are not a good predictor of the hosts where larvae perform the best. Jezorek et al. They found that Opuntia engelmannii vars. One of the best hosts for offspring survival and development, Opuntia streptacantha, was one of the least preferred by females. Many factors can lead to a mismatch between female egg-laying preferences and offspring performance; however, in this case the new association of Cactoblastis cactorum with North American Opunia plants is likely a cause.
Cactoblastis and its novel hosts have had only a short evolutionary history, and the moth probably has not had a chance to adapt to its new host plants.
Figure 4. Cactus pad dissected to show larvae of cactus moth, Cactoblastis cactorum Berg , feeding within. Sapelo Island, GA Larvae do not perform well on Opuntia cladodes with a tough skin, such as Opuntia engelmannii variety lindheimeri and Opuntia macrocentra. The larvae appear to have a difficult time burrowing through the tough epidermal layer and get stuck in the secreted mucilage Jezorek et al.
Figure 5. Damage from Cactoblastis cactorum. Left to right: recent to older damage. The frass from the moth is visible in the left fresh frass and mucilage oozing from holes in the cladode and middle photos dried frass.
In Queensland, 16 million acres of severely infested land were reclaimed for agriculture by the action of this insect. In fact, the town of Dalby in Queensland, Australia erected a monument in dedicated to Cactoblastis cactorum for saving the people of Queensland from the scourge of invasive prickly pear cactus. This moth has been an effective control agent of Opuntia spp. In , it was introduced into the Caribbean, in Nevis, where the control of Opuntia curassavica and other Opuntia spp.
Eggs and larvae, or infested cladodes, were sent from Nevis to Montserrat and Antigua in and to Grand Cayman in Bennett et al. As mentioned above, the arrival of Cactoblastis cactorum into continental North America is a major concern. It has high potential to destroy native Opuntia spp. Rafinesque, as well as exotic species, either naturalized or grown as ornamentals, in Florida are also at risk.
Another concern is the probability that Cactoblastis cactorum will spread west as far as Texas and into Mexico. In these desert regions, wild Opuntia and Cylindropuntia Engelmann Kreuzinger species provide food and nesting sites for a variety of wildlife and contribute to soil stability Chavez-Ramirez et al. Opuntia is important economically as well.
These plants are harvested on over three million hectares in Mexico where they grow naturally Soberon et al. In addition, , hectares of Opuntia and Nopalea species are cultivated for human and livestock food, for fuel, and for manufacturing. These plants are valued in Mexico at over 80 million dollars annually Soberon et al. The devastating affect of Cactoblastis cactorum on cactus growth is well known. Management Back to Top No satisfactory method of chemical control of Cactoblastis cactorum is known.
Similarly, inundative releases of egg parasites such as Trichogramma could have an adverse affect on other desirable Lepidoptera. Efforts to control this invasive species have been focused on containing the spread via quarantine, as well as development of fungal, bacterial, parasitoid, and nematode biological control agents.
Sterile insect technique is also a possible management tool Hight et al. In its native habitat in South America several natural enemies are known including Apanteles alexanderi Brethes Braconidae , Phyticiplex doddi Cushman and Phyticiplex eremnus Porter Ichneumonidae , Brachymeria cactoblastidis Blanchard Chalcididae , and Epicoronimyia mundelli Blanchard Tachinidae. The host range of these natural enemies would have to be determined before the release of any of these for the control of Cactoblastis cactorum could be approved.
Surveys between July and December revealed that egg-sticks of Cactoblastis cactorum in north Florida are attacked by egg parasitoids in the genus Trichogramma: Trichogramma pretiosum Riley, Trichogramma fuentesi Torre, and an additional unidentified Trichogramma species belonging to the Trichogramma pretiosum group. Unfortunately, Paraiso et al. However, with laboratory rearing and inundative releases, Trichogramma wasps could be integrated in the current pest management system.
A review of biological control of pests in the Commonwealth Caribbean and Bermuda up to July Video of the dissection of the male genitalia of the cactus moth, Cactoblastis cactorum.
Ecological characterization of Opuntia clones in South Texas: Implications for wildlife herbivory and frugivory. Journal of the Professional Association for Cactus Development 2: Dodd AP. The biological campaign against prickly-pear. Commonwealth Prickly-pear Board Bulletin, Brisbane, pp. Journal of Agriculture of the University of Puerto Rico Developing a sterile insect release program for Cactoblastis cactorum Berg Lepidoptera: Pyralidae : Effective overflooding ratios and release-recapture field studies.
New World monkeys dig the larvae and pupae out from the flattened leaf-like stems, or " cladodes ", of the cacti. Recent work in South America has identified four genetically-structured  ecotypes of C. The moth can be identified only by a microscopic examination of dissected male genitalia. They generally appear as typical Pyralidae , with the pronounced labial palps of the female, thus the name "snout moths".