Host-specificity tests were conducted involving two provenances of D. tomentosus: one collected from C. imbricata in South Africa (henceforth called the imbricata provenance) and one collected from C. rosea

Host-specificity tests were conducted involving two provenances of D. tomentosus: one collected from C. imbricata in South Africa (henceforth called the imbricata provenance) and one collected from C. rosea in Mexico (henceforth called the rosea provenance). These provenances were reared on both C. imbricata and the target weed, Cff. On the target weed, the imbricata provenance survived poorly and insects of the rosea provenance did not complete their life cycle. However, both populations thrived on C. imbricata. This remarkable finding led to a reassessment of the target weed which was subsequently identified as Cylindropuntia fulgida var. fulgida, whose native range is the Sonoran desert of Arizona and Mexico.