Within-tree models of
Dendroctonus frontalisgeneration survival from attacking adults to emerging adults and survivorship from eggs to emergence were developed for five regions of the infested tree bole of Pinus taedaL. The generation survival model (GS) describes the number of D. frontalis/attacking adult as a function of time at a specific height. The form of the model is
YGS = 1.0 + C(1e20.0X)eA(1.0X)B + .
The survival model (S) describes the number of
D. frontalis/100 eggs as a function of time at a specific height. The form of this model is
YS = CeA(1.0X)B + .
The generation survival model indicated that the rate of survival was primarily a function of generation development time, rather than position on the infested tree bole. The rates also varied in different sections of the tree depending on the initial egg/attacking adult population of
D. frontalis. The emergence/attack ratios for the tree sections were slightly greater at the top and bottom than in the middle of the infested bole.
The survivorship curves, based on an initial cohort of 100 eggs, were similar for the various sections of the tree bole. Again, the rate of population change was primarily a function of developmental time, rather than position on the tree. The curves for the various tree sections were essentially the same.
The combined action of the various biotic and abiotic mortality agents acting in the different sections of the tree resulted in essentially uniform survivorship throughout the infested portion of the tree bole.