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)
S. Polavarapu et Wd. Seabrook, 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), Canadian Entomologist, 128(2), 1996, pp. 187-198
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.