Use population data to connect changing food availability and biotic factors such as disease and competition with increases or declines in animal populations.
The prickly pear cactus (Opuntia stricta) was first recorded in Kruger National Park, South Africa, in 1950 . It spread rapidly, mainly through seeds being dispersed by baboons and elephants.
In 1997, the cactus moth (Cactoblastis cactorum) from South America was introduced into the area as a biological control. The larvae of the moth feed on the cactus. The graph shows the number of cladodes (flattened stem sections) of cactus found per in the years before and after the introduction of the cactus moth.
Explain the change in numbers of the cactus moth throughout the study period.