Published online by Cambridge University Press: 31 May 2012
The biological control of agricultural pests is not dependent on the specific identification of the natural enemies employed if their host relations are known. Such identification is often made after the natural enemies are imported and established in a new habitat. This is well exemplified by the genus Aphytis, a genus notable for species that consist of “host-controlling” and “non-host-controlling” races and for certain species that, after importation from South China into California and Israel, were colonized by two methods, direct and indirect. The direct method is characterized by the “screening out” of species in the field, the indirect method by the “screening out” of species in the laboratory.