Host-plant affinities of two biotypes of Dactylopius opuntiae (Homoptera: Dactylopiidae): enhanced prospects for biological control of Opuntia stricta (Cactaceae) in South Africa.
In an attempt to improve the biological control of O. stricta in South Africa, a stock of D. opuntiae was obtained from O. stricta in Australia during 1996. Host-specificity tests confirmed that the newly imported D. opuntiae from Australia is a different biotype to the one already established in South Africa. The Australian ('stricta') biotype thrived on O. stricta but was unable to develop satisfactorily on O. ficus-indica, while the converse was true for the South African ('ficus') biotype, which thrived on O. ficus-indica but fared poorly on O. stricta. The integrity of the host-plant specificity of the two biotypes of D. opuntiae has important implications for biological control of Cactaceae in South Africa, and has greatly enhanced prospects that O. stricta can be brought under biological control successfully.