How did prickly pear cacti become widespread outside the Americas?

Prickly pear cacti (Opuntia), which belong to the Cactaceae family within the Caryophyllales order, are native to the Western Hemisphere. Their widespread presence outside the Americas is the result of human introduction.123

Following the discovery of the Americas, various Opuntia species were introduced to the Mediterranean region, where they began growing wild. They were subsequently introduced to other parts of the world, including India, the Malayan region, Hawaii, Australia, and South Africa, often for cultivation as food crops or ornamentals.312

These cacti are easily propagated from stem segments, which facilitated their spread. Once introduced to new environments, they often prospered because they were separated from their natural parasites and competitors. In regions like Australia and South Africa, this lack of natural control allowed them to become invasive species and significant pests, eventually necessitating the introduction of specific moths from their native habitat to bring them under control.123