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Opuntia monacantha (tree, shrub, succulent)   |
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Interim profile, incomplete information
Management Information
Biological: Cochineal (Dactylopius spp.) and Cactoblasts (Cactoblastis spp.) are the two most important biological control agents for prickly pear cacti. The two attack the cactus in a totally different manner. Cochineal species attach to the outside of the plant and sucks the moisture out of the plant. Cactoblasts are black and yellow striped grubs that tunnel into and devour the inside of the plant (North West Weeds 2007). Cactoblastis oviposits by gluing sticks of about 50 to 90 eggs on cactus spines; the gregarious larvae bore into the pads or cladodes, devouring them from the inside (Stiling 2002). Because of its oligophagous feeding habits Cactoblastis has been successful against a whole range of Opuntia species including 11 species of North American origin (Julien and Griffiths 1998, in Stiling 2002). Following the release of Cactoblastis cactorum in Australia the prickly pear Opuntia monacantha population collapsed (Dodd 1940, in Stiling 2002). The success of Cactoblastis in Australia was followed by introductions to control pest Opuntia in South Africa, St. Helena, Hawaii, New Caledonia, Pakistan, Kenya and Ascension Island. In 1913 Dactylopius ceylonicus was introduced into South Africa and achieved control of Opuntia vulgaris within a few years. In 1928 D. ceylonicus and Dactylopius opuntiae were used as biological control agents in Mauritius against Opuntia vulgaris and O. Tuna. In 1950 the cactus moth C. cactorum was also introduced in Mauritius for the purpose of controlling O. vulgaris. In 1974 C. cactorum was introduced to Ascension in an attempt to control O. vulgaris (Ascension Island Conservation Centre Undated).  
Location Specific Management InformationAmerican Samoa
Opuntia monacantha is described as a "moderate invader" in Samoa and American Samoa. It is a proclaimed a noxious weed (Parham 1972, in SPREP 2000). Ascension Is.
Opuntia spp. (not identified specifically) have been controlled on Saint Helena and Ascension by the introduction of the cactus moth Cactoblastis cactorum in 1973 and 1971, respectively. The success of C. cactorum in Australia was followed by introductions of the biocontrol agent South Africa, St. Helena, Hawaii, New Caledonia, Pakistan, Kenya and Ascension Island. At Ascension, a new postage stamp adorned with a portrait of the caterpillar attests to the esteem in which Cactoblastis is held (Stiling 2002).
Farm reports for the 1890s described efforts to control Opuntia sp., Psidium sp. and Catharanthus sp. by burning and poisoning because they were invading pasture land (Duffey 1964). Australia
Following the release of Cactoblastis cactorum in Australia 90 percent of the prickly pear population collapsed (Dodd 1940, in Stiling 2002). Cactoblastis oviposits by gluing sticks of about 50 to 90 eggs on cactus spines. The gregarious larvae bore into the pads or cladodes, devouring them from the inside. Fiji
Opuntia monacantha is described as a "moderate invader" in Fiji. It is a proclaimed a noxious weed (Parham 1972, in SPREP 2000). Fiji
A declared noxious weed in Fiji and Samoa. O. monacantha is moderately invasive in these two locations (Meyer 2000, in PIER 2006). Mauritius
In 1928 Dactylopius ceylonicus and D. opuntiae were used as biological control agents in Mauritius against Opuntia monacantha and O. tuna In 1950 the cact.us moth Cactoblastis cactorum was also introduced for the purpose of controlling O. monacantha. Saint Helena
Opuntia spp. (not identified specifically) have been controlled on Saint Helena and Ascension by the introduction of the cactus moth Cactoblastis cactorum in 1973 and 1971, respectively. Samoa
Opuntia monacantha is described as a "moderate invader" in Samoa and American Samoa. It is a proclaimed a noxious weed (Parham 1972, in SPREP 2000). South Africa
In South Africa Dactylopius ceylonicus Green was obtained from the Queensland Prickly Pear Commission and introduced into South Africa in 1913. It achieved successful control of Opuntia monacantha within a few years. Upolu Is.
A declared noxious weed in Fiji and Samoa. O. monacantha is moderately invasive in these two locations (Meyer 2000, in PIER 2006).
Management Resources/Links
3. IUCN/SSC Invasive Species Specialist Group (ISSG)., 2010. A Compilation of Information Sources for Conservation Managers.
Summary: This compilation of information sources can be sorted on keywords for example: Baits & Lures, Non Target Species, Eradication, Monitoring, Risk Assessment, Weeds, Herbicides etc. This compilation is at present in Excel format, this will be web-enabled as a searchable database shortly. This version of the database has been developed by the IUCN SSC ISSG as part of an Overseas Territories Environmental Programme funded project XOT603 in partnership with the Cayman Islands Government - Department of Environment. The compilation is a work under progress, the ISSG will manage, maintain and enhance the database with current and newly published information, reports, journal articles etc. 4. Stiling, P. 2002. Potential non-target effects of a biological control agent, prickly pear moth, Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae), in North America, and possible management actions. Biological Invasions 4: 273-281, 2002. Results Page: 1
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