CONSTANT TEMPERATURE LIFE TABLE STUDIES OF POPULATIONS OF GRAPE PHYLLOXERA FROM WASHINGTON AND OREGON, USA
Grape phylloxera is a recent pest threatening to destroy over 1100 ha of selfrooted winegrapes in the Pacific Northwest region of the USA. Some vineyards have coexisted with this pest for over 15 years while others have been devastated in less than 5 years. We conducted this study to determine if life processes of populations of phylloxera from four different areas in the Pacific Northwest, USA, would show differences in survival, development and reproduction when reared at myriad of constant
... yriad of constant temperatures (3 -36ºC at 3º intervals). Individual differences were observed among the four populations for development, survival and reproduction. Nevertheless, the numbers for each parameter followed a general trend among temperatures. The optimum temperature range for maximum response for all parameters was between 24ºC and 27ºC. Upper and lower temperature thresholds were, respectively, <6ºC and >33ºC. The results from this study and others support the hypothesis that localized differences in 'virulence' of infestations from vineyard to vineyard over an appellation may be a function, in part, of localized temperature differences caused by such factors as soil type, aspect, slope, pruning, ground cover, and plant spacing.