SEASONAL DIAPAUSE DEVELOPMENT, EFFECTS OF TEMPERATURE AND PHOTOPERIODON POSTDIAPAUSE EGG DEVELOPMENT, AND VALIDATION OF A DEGREE-DAY MODELPREDICTING LARVAL ECLOSION OF BLUEBERRY LEAFTIER, CROESIA-CURVALANA (KEARFOTT) (LEPIDOPTERA, TORTRICIDAE)

Eggs of blueberry leaftier, Croesia curvalana (Kearfott), were transfe rred from outdoors at 15-day intervals from 15 November to 1 March and held in the laboratory at 20 degrees C, 16L:8D. Mean hatching time co ntinually decreased with each successive transfer date and was signifi cantly shorter for eggs transferred on 1 March compared with any previ ous transfer date. Transfer date also had a significant effect on perc entage hatch, which generally increased with longer exposure of eggs t o outdoor conditions. Mean hatching time was longer under 10L:14D phot operiod than at 13L:11D or 16L:8D conditions at all three temperatures studied. Rate of postdiapause development was linearly related to con stant temperatures in the range from 6 to 25 degrees C, but appeared t o have deviated from linearity at 30 degrees C. The lower threshold te mperature for postdiapause development of eggs was estimated to be 3.4 degrees C. Means of 60, 77, and 97 degree-days above a lower threshol d of 3.5 degrees C were required for hatching of the 10th, median, and 90th percentile of eggs under laboratory conditions, respectively. In each of 3 years, eclosion of first-instar larvae occurred over a 10- to 17-day period in late April to mid-May. Degree-day accumulations ba sed on litter temperatures in the field predicted the dates of 10th, 5 0th and 90th percentile eclosion of first-instar larvae within +/-2 da ys of the observed dates.