Nom taxonomique: Cactoblastis cactorum Berg
Synonymes: Zophodia cactorum Berg
Noms communs: cactus moth, prickly pear moth
Type d'organisme: insecte
Cactoblastis cactorum est une mite qui se nourrit sur des espèces de cactacées. Elle a été introduite dans divers endroits autour du globe pour le contrôle biologique des cactus envahissants et elle s'est établie avec succès en Australie et dans quelques îles des Caraïbes. Cependant, depuis les Caraïbes elle s'est étendue en Floride et elle a attaqué des espèces de cactus non-cibles. On craint qu'elle puisse causer une perte à grande échelle de la diversité des cactus indigènes d' Amérique du Nord et qu'elle puisse avoir un grand impact économique, social et écologique dans les zones riches en Opuntia du sud ouest des Etats-Unis et du Mexique.
Females of Cactoblastis cactorum have a wingspan of 27-40mm, whilst the males wingspan is slightly smaller (23-32mm). The adult is fawn with faint dark dots and lines on the wings. It normally rests with its wings wrapped around its body. The forewings are greyish brown but whiter toward the costal margin. Distinct black antemedial and subterminal lines are present. Hindwings are white, semihyaline at base, smoky brown on outer half with a dark line along the posterior margin. The average longevity of the adult is 9 days. The incubation period of eggs depends on temperature; the shortest time being 18 days. The eggs usually hatch in 23-28 days. Larvae are gregarious in nature, initially pinkish cream coloured, with black red dots on the back of each segment. Later instars become orange and the dots coalesce to become a dark band across each segment reaching up to 1.5cm. The pupa is enclosed in a fine white silk cocoon which consists of a loose outer covering and a more compact inner cocoon. Pupation sites are usually found among debris of rotting cladodes under stones, logs, bark and just beneath the surface of the soil. The average length of the pupal period is 21-28 days. (Jordan Golubov., pers. comm.., 2005).
Description de l'habitat
Cactoblastis cactorum require Opuntia cacti species to lay their eggs upon.
Stiling (2002) states that, "Cactoblastis cactorum oviposits by gluing sticks of about 50-90 eggs on cactus spines. The gregarious larvae bore into the pads or cladodes, devouring them from the inside. About four pads are needed for the development of the larvae from a complete egg stick." The authors also report that, "There are at least 31 species of prickly pear in the US that are likely to be attacked by C. cactorum and 56 species in Mexico. As well as the threat to wild cacti, there are over 250,000ha of Opuntia plantations in Mexico that support a thriving agricultural industry, most of which is centered on harvesting fruits or pads."
Stiling (2002) reports that “As well as its commercial value, Opuntia is used by a whole community of organisms (109 species of invertebrates, 9 species of reptiles, 54 mammals and 25 species of birds)". Vigueras and Portillo, 2001; Mellink and Rojas-Lopez, 2002).
Cactoblastis cactorum is a voracious feeder on cacti in the genus Opuntia (prickly pear cacti) and is an example of a successful weed biological control programme. It was introduced from Argentina into Australia in the mid 1920's for the biological control of invasive and non-native Opuntia. C. cactorum was then intentionally spread from Australia into other countries with prickly pear problems (Solis et al. 2004).
Native range: South America (Zimmermann et al. 2000). Northern provinces of Argentina (Entre Rios, Corrientes, Santa Fe, northern portion of Cordoba, Santiago del Estero, Tucuman, Salta, Jujuy and the Chaco), in Uruguay (along the Uruguay and Plata Rivers from Piriapolis in the south and north to Salta) and Paraguay (Villa de Concepcion and vicinities of Asuncion), also in the southern portions of Brazil (Matto Grosso at Corumba but may include Rio Grande do Sul and Santa Catarina). (Jordan Golubov., pers. comm., 2005)
Known introduced range: Africa, Asia, Australasia-Pacific region and North America (Stiling, 2002).
Informations pour la gestion de l'espèce
For details on preventative measures, chemical, physical, and biological control options of Cactoblastis cactorum, please see management information compiled by ISSG.
On hatching, all larvae from one eggstick enter the plant at one point. They tunnel freely within the cladodes, consuming the whole of the interior except the vascular bundles and leaving the undamaged cuticle as a transparent tissue. Burrowing activity usually causes secondary bacterial activity which hastens the destruction of cladodes. When one cladode has been eaten or decayed, the larvae may penetrate into the next segment. During this process the colony usually divides into two or more groups. Adults have no functional mouthparts and emerge only to reproduce (Jordan Golubov., pers. comm., 2005).
Oviposition is normally at dusk or early dawn and may be responding to CO2 concentrations around pads (Stange, 1997; Stange et al 1995). The number of eggs in a stick varies greatly but the average contain from 76-90 eggs. Each female can deposit several eggsticks; 3-4 but can frequently lay 8-12. In Australia, mating takes place during the early morning hours and copulation has never been documented at night, or after 2100hrs. Adults normally remain inactive during daylight hours. In South Africa, sexual activity is found on the first and second night after adult emergence. In Florida, peak periods of sexual activity begin between nautical and civil twilight and ends before sunrise (for a detailed behavioural sequence of sexual activity see Hight et al. 2003)
Stades du cycle de vie
When fully grown the larvae exit the cladodes and individually drop to the ground and find pupation sites, usually in the debris of rotting cladodes (Jordan Golubov., pers. comm., 2005).
Révisé par: Dr. Jordan K. Golubov
Profesor-Investigador Titular C
Lab. Sistematica y Ecologia Vegetal
Departamento El Hombre y Su Ambiente
Universidad Autonoma Metropolitana -- Xochimilco Mexico
Sources principales: Stiling, 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
Compilé par: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
Dernière mise à jour: Thursday, 27 March 2008