POTENTIAL USE OF BIOLOGICAL CONTROL TO REGULATE CACTOBLASTIS CACTORUM

Authors: PEMBERTON, R - USDA, ARS, IPRL; Hight, Stephen

Submitted to: Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/5/2004
Publication Date: 7/27/2004
Citation: Pemberton, R.W., Hight, S.D. 2004. Potential use of biological control to regulate cactoblastis cactorum. Meeting Proceedings.

Interpretive Summary:

Technical Abstract: Cactoblastis cactorum Berg. is an invasive moth in North America where it threatens many native and economic species of Opuntia cacti in the USA and Mexico. A variety of biological control approaches are discussed that have potential against this moth. However, employing biological control against C. cactorum represents a risk of negative non-target impacts to the many closely related North American moths in the subfamily Phycitinae that feed on various species of Cactaceae. Besides loss of biodiversity, an additional risk of non-target impacts from a biological control project would be that in lowering the populations of moths that likely regulate native species of Opuntia could allow these species of cacti to become weedy and increase in their pest status. The various biological control approaches are ranked according to their increasing risk of non-target impacts as follows: 1) classical introduction of parasitoids and pathogens from the native range of the moth in South America that are specific to the genus Cactoblastis; 2) innundative releases in Florida of parasitoids known to attack C. cactorum in Florida; 3) innundative releases in Florida of generalists parasitoids known to attack C. cactorum in Florida; 4) classical introduction of host-specific parasitoids that attack closely related North American gregarious larvae that feed on species of Cactaceae; 5) classical introduction of host-specific parasitoids that attack any North American Cactaceae feeding moth; and 6) classical introduction of generalist parasitoids from South America that also attack species of Cactoblastis. Biological control probably can reduce the local abundance of C. cactorum populations but is unlikely to prevent the westward spread of the moth. The relative benefits and risks of biological control need to be carefully assessed prior to the initiation of any operational biological control programs. It will be difficult to reach agreement on acceptable levels of risk if the likely benefits cannot be predicted. Other management options for C. cactorum that produce lower risk of non-target impacts need to be considered.