Author
 |
Pemberton, Robert |
|
LIU, HONG - UNIVERSITY OF FLORIDA |
|
Submitted to: Biological Control
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 2/2/2007 Publication Date: 5/14/2007 Citation: Pemberton, R.W., Liu, H. 2007. Control and persistence of native Opuntia on Nevis and St. Kitts, fity years after the introduction of Cactoblastis cactorum. Biological Control. 41:272-282. Interpretive Summary: Cactoblastis cactorum is a famous biological control agent of weedy prickly pear (Opuntia) cacti. This argentine moth had been used successful in Australia and localities in the Old World. Then in 1956 it was introduced to the Island of Nevis in the West Indies for the control of weedy native Opuntia in pastures. Within a few years the moth reduced the target cacti and then spread on its own and was moved by people to other islands in the Caribbean. In 1989 it was found in the Florida Keys attacking native Opuntia. Since that date it has spread northward and threatens to move west into the prickly pear rich American West and Mexico. There is considerable concern about the moth’s potential harm to American and Mexican Opuntia. We assessed the presence and status of Opuntia species and C. cactorum on Nevis and St. Kitts fifty years after its introduction to learn the outcome this historic biocontrol effort and to obtain information that might inform the discussion related to the moth’s threat to native Opuntia in North America and Mexico. Cactoblastis cactorum occurred at 10/16 sites and attacked 22.7% of total plants. Of the 4 Opuntia found, 3 were attacked, including the native targets O. triacantha (with 15.6% of plants and 8.9% of pads attacked) and O. dilleni (with 44.4% plants and 8.1% pads attacked), and the cultivated and naturalized O. cochenillifera (with 19.1% plants and 1.2% pads attacked). The native nontarget tree pear, O. rubesens, was not attacked. Larger and wild plants had significantly higher rates of attack. Biocontrol of O. triacantha and O. dillenii persists and these natives have survived 50 years of C. cactorum attack on these small islands, despite fears that the moth could have caused their extinction. These findings suggest C. cactorum’s potential impact on native North American and Mexican Opuntia will be significant but variable and not necessarily catastrophic. Efforts to control the moth and limit its spread are still seen as very important. Technical Abstract: Since Cactoblastis cactorum appeared in Florida in 1989, via importation of infested horticultural Opuntia plants and/or natural spread from the Caribbean, there has been a concern about the moth’s threat to native and economic North American and Mexican Opuntia. The moth’s occurrence in the Caribbean is due to its introduction to Nevis Island in 1956 for the control of native Opuntia that were pasture weeds. We assessed the presence and status of Opuntia species and C. cactorum on Nevis and St. Kitts fifty years after its introduction to learn the outcome this historic biocontrol effort and to obtain information that might inform the discussion related to the moth’s threat to native Opuntia in North America and Mexico. Cactoblastis cactorum occurred at 10/16 sites and attacked 22.7% of total plants. Of the 4 Opuntia found, 3 were attacked, including the native targets O. triacantha (with 15.6% of plants and 8.9% of pads attacked) and O. dilleni (with 44.4% plants and 8.1% pads attacked), and the cultivated and naturalized O. cochenillifera (with 19.1% plants and 1.2% pads attacked). The native nontarget tree pear, O. rubesens, was not attacked. Larger and wild plants had significantly higher rates of attack. Biocontrol of O. triacantha and O. dillenii persists and these natives have survived 50 years of C. cactorum attack on these small islands, despite fears that the moth could have caused their extinction. These findings suggest C. cactorum’s potential impact on native North American and Mexican Opuntia will be significant but variable and not necessarily catastrophic. |
