Biosystematics ofAmblyseius andersoni andA. potentillae (Acarina: Phytoseiidae): Implications for biological control

Populations of Amblyseius andersoni Chant from Verona, Italy and Oregon, U.S.A. and of A. potentillae (Garman) from The Netherlands were hybridized in reciprocal crosses and examined for evidence of genetic isolation and morphological or isozyme discrimination. Hybridization studies showed that all crosses between the three populations produced viable and fertile female offspring. Backcrosses of F1 hybrid females of males of the maternal strain likewise showed no evidence of genetic isolation. It is concluded that the populations are conspecific, and that A. potentillae should be recognized as a junior synonym of A. andersoni. Morphological examination showed that the Oregon and Netherlands biotypes were more similar to one another than either was to the Italian biotype. A linear discriminate-function analysis correctly classified the mites 78.3% of the time, with only 5% of the misclassifications involving the Italian biotype. Polyacrylamide gel electrophoresis of esterase isozymes showed distinct bands of enzyme activity with significantly different R(f) values for each of the three populations. The genetic continuity between the biotypes should allow us to incorporate specific biological traits of value for biological control in Oregon by hybridization with the other populations, while the morphological and electrophoretic markers may allow us to track the degree of establishment and dispersal which occurs under field conditions when foreign biotypes are introduced.