Pineapple
Pineapples are normally seedless, and they must be propagated vegetatively. The clones are somewhat unstable, and tend to produce mutants with some frequency. As a consequence, many clones are known.
However, one clone, consisting of a number of closely similar mutants, dominates pineapple cultivation, worldwide.
This is “Cayenne” which was first take to Europe (for greenhouse cultivation) in 1820, but is believed to have originated in Venezuela many centuries earlier.
Modern cultivators complain that this clone is susceptible to several parasites, particularly the mealy bug wilt, which results from the destruction of the roots by the insect Dysmicoccus brevipes.
It is now thought that much of this susceptibility may result from an environment erosion of horizontal resistance, or from a loss of biological controls.
“Cayenne” dominates world production because of its excellent yield and quality, and its slightly susceptible to parasites does not prevent this domination.
Most other cultivars have considerable higher levels of resistance to the few known parasites do pineapple.
