OVIPOSITION AND EMERGENCE OF OLIVE SCALE (HOMOPTERA, DIASPIDIDAE) CRAWLERS - REGIONAL DEGREE-DAY FORECASTING-MODEL

We investigated the temperature-driven onset and rate of oviposition a nd egg hatch of the spring generation of the olive scale, Parlatoria o leae (Colvee), in northern Israel. Phenology was studied between 1992 and 1994 at different elevations (between 80 and 820 m above sea level ) and on 2 different host species (apple, Malus silvestris Miller, and pear, Pyrus communis L.). The association between accumulation of deg ree-days (DD) and rate of oviposition and egg hatch was analyzed with simple linear regression using 10 degrees C as the lower developmental threshold temperature and 15 February as the starting date. Temperatu re-driven rates of oviposition and egg hatch were similar for the 3 yr , all elevations, and the 2 tree species. Elevation, host species, and year did not meaningfully affect the amount of thermal units required by P. oleae to initiate oviposition and egg hatch. Oviposition and eg g hatch is expected to begin at 40.1 and 184.8 DD, respectively. The m odel accurately predicted the onset of egg hatch during 2 yr consecuti vely in 1 tested plot (deviations between observed and expected dates of <3 d).