Submitted to: Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/5/2004
Publication Date: 7/27/2004
Citation: Solis, A., Hight, S.D. 2004. Taxonomy and identification of cactoblastis cactorium. Meeting Proceedings.
Technical Abstract: The South American cactus moth, Cactoblastis cactorum Berg. (Pyralidae; Phycitinae), was found in North America for the first time in 1989. The insect has spread from the Florida Keys and now occurs along the coastal area of southeastern USA from the tip of the Florida panhandle into South Carolina. Cactoblastis cactorum is attacking and destroying native species of prickly pear cacti (Opuntia spp.) and represents a substantial threat to the southwestern USA and Mexico, areas that are rich in Opuntia spp. diversity. Obtaining accurate identifications of this insect is important as its range expands and the likelihood remains that isolated infestations may occur well beyond the leading edge of the insects' current distribution. There are 142 species in 33 genera of phycitine moths in the western hemisphere. However, after excluding three predaceous genera (20 spp.), seven non-Cactaceae plant feeding genera (59 spp.), and seven genera with unknown larval hosts (18 spp.), 45 species in 16 genera of Phycitinae feed on Cactaceae. If C. cactorum moves onto Opuntia spp. in the western USA and Mexico, the insect will need to be distinguished from this large number of phycitine moths that are associated with host plants in the family Cactaceae. At least 36 species in 10 genera of native phycitine moths feed on Cactaceae in Mexico and the USA. Identification of the Cactaceae feeding Phycitinae is difficult because the adults are similar in appearance and distinction to species usually requires dissection of genitalia. Larval characteristics and host plant species are useful in distinguishing between species but larval information is often lacking. For example, the 10 genera of cactus-feeding Phycitinae that occur in the USA are represented by 28 species but only 14 of those species have known larvae; larvae and host plants of the other 14 species are unclear. The present invasive distribution of C. cactorum in the USA overlaps with only three other species of phycitine larvae associated with Opuntia spp.; Melitara prodenialis Walker; Ozamia lucidalis (Walker); and Rumatha glaucatella (Hulst). Larvae of the three native species are easily distinguished from the bright orange-red, black-spotted caterpillars of C. cactorum and only M. prodenialis is distributed beyond extreme southern Florida; overlapping with C. cactorum from South Carolina to Texas. Melitara prodenialis also has internal feeding gregarious larvae that are produced in eggsticks similar to C. cactorum.