SYNCHRONIZATION OF LARVAL EMERGENCE IN WINTER MOTH (OPEROPHTERA-BRUMATA L) AND BUDBURST IN PEDUNCULATE OAK (QUERCUS-ROBUR L) UNDER SIMULATED CLIMATE-CHANGE

1. The hypothesis that a 3 degrees C elevation in temperature and doub led CO2 concentration would have no effect on the synchronization of w inter moth egg hatch with budburst in oak was tested by comparing the separate and interactive effects of ambient and elevated (+ 3 degrees C) temperature and ambient and elevated (doubled to 340 p.p.m.) CO2 in eight experimental Solardomes. In addition, an outdoor control was co mpared with the ambient temperature/CO2 treatment combination. 2. Elev ated temperature accelerated darkening (preceding egg hatch by about 5 -10 days) and hatching of eggs developing off the trees; elevated CO2 had no effect. The same effects were observed in eggs developing on th e trees. 3. Within treatments, date of egg hatch was the same on trees with early or late budburst. 4. Egg darkening and budburst were close ly synchronized at both ambient and elevated temperatures. 5. Both egg s and trees required fewer cumulative heat units (day degrees > 4 degr ees C), for hatching and budburst, respectively, at ambient than eleva ted temperatures. The requirements in the outdoor control treatment we re similar to those in the ambient Solardome treatment. 6. Egg hatch b etween 10 and 25 degrees C, on a temperature gradient in the laborator y, required a constant number of heat units; fewer were required below 10 degrees C. 7. Elevated temperatures, in the Solardomes and the fie ld, delayed adult emergence from the pupae. 8. The results suggest tha t a general increase in temperature with climatic change would not aff ect the closeness of the synchronization between egg hatch of winter m oth and budburst of oak.