Abstract
Reproductive compatibility and morphological differences in the aedeagus were investigated for the diapausing (Dc) and non-diapausing (Nc) types of P. citri, and for P. ulmi (U). The duration of copulation was shorter when Dc_??_ was paired with any female type compared to other crosses. Among the crosses with Dc_??_, the duration of copulation increased successively with Nc_??_, U_??_ and Dc_??_. There was reproductive incompatibility between Dc and U but the mechanism is not clear. Morphological differences in the aedeagus were found between Dc, Nc and U. The aedeagus of Dc is similar to that of U but it can be distinguished by a bent hook top. A remarkable difference was found in the shape of the aedeagus between Dc and Nc.
