 There is great diversity in the genotype and phenotype of wild strains.While wild strains are highly adaptable and may be heterokaryotic (contain nuclei of dissimilar genotype within a single organism, and hence highly variable), strains used for biocontrol in commercial agriculture are, or should be, homokaryotic (nuclei are all genetically similar or identical).This, coupled with tight control of variation through genetic drift, allows these commercial strains to be genetically distinct and nonvariable.