Winter Survival of the Non-Diapausing Population of the Citrus Red Mite, Panonychus citri(MCGREGOR)(Acarina : Tetranychidae)on Pear and Citrus

Abstract

Patterns of hatching and winter survival were studied on the eggs of non-diapausing populations of Panonychus citri (MCGREGOR) on pear and citrus in Takatsuki, Osaka Prefecture, together with changes in population density and stage structure of the populations.Most non-diapausing eggs laid on pear twigs in autumn hatched by mid-December and the individuals that hatched from the eggs all starved to death. Eggs that had not hatched by that time could not successfully overwinter at all, whereas on citrus the eggs as well as the other stages survived the winter. On pear no individuals of P. citri were observed until mid-August but thereafter the population showed a rapid increase to an outbreak level. These results showed that the non-diapausing population on pear connot maintain itself throughout the year and the population consists of immigrants from outside of the pear orchard.