The western spruce budworm model: structure and content.

Abstract

In 1977, the United States Department of Agriculture and the Canada Department of the Environment agreed to cooperate in an expanded and accelerated research and development effort, the Canada/United States Spruce Budworms Program (CANUSA), aimed at the spruce budworm in the East and the western spruce budworm in the West. The objective of CANUSA was to design and evaluate strategies for controlling the spruce budworms and managing budworm-susceptible forests, to help forest managers attain their objectives in an economically and environmentally acceptable manner. The work reported in this publication was wholly funded by the Program. This manual is one in a series on the western spruce budworm.

Modeling Spruce Budworm Population Revisited: Impact of Physiological Structure on Outbreak Control

“…τ = ln(q 1 /D)/d is very important for the eradication of budworm population. In reality, however, since each female lays about 200 eggs on average (Fleming and Shoemaker, 1992;Sheehan et al, 1989;Royama, 1984), q 1 is very large compared to D andd. This causes the delay τ to be less than ln(q 1 /D)/d, which results in B > A.…”

“…Some parameters are available in the literature while others are calculated or estimated based on the information collected from the literature (Blais, 1981;Crawford and Jennings, 1989;Fleming and Shoemaker, 1992;Ludwig et al, 1978Ludwig et al, , 1979Redak and Cates, 1984;Sheehan et al, 1989;Royama, 1984;Royama et al, 2005). As given in Ludwig et al, (1978Ludwig et al, ( , 1979 we use β = 105,700 larvae/hectare/year, γ = 69,748 larvae.…”

“…The mature mortality rate D varies widely due to its dependence upon temperature, amount of tree foliage, dispersal rate, etc. (Sheehan et al, 1989;Royama, 1984). Based on the observation in Blais (1981); Sheehan et al (1989), where the range of spruce budworm mortality was mentioned to be 0-48%, we use D = 0.30 for our baseline computation.…”

“…(Sheehan et al, 1989;Royama, 1984). Based on the observation in Blais (1981); Sheehan et al (1989), where the range of spruce budworm mortality was mentioned to be 0-48%, we use D = 0.30 for our baseline computation. A maximum amount of eggs is produced when the temperature is suitable and there are plenty of foliages.…”

“…As given in Ludwig et al, (1978Ludwig et al, ( , 1979 we use β = 105,700 larvae/hectare/year, γ = 69,748 larvae. Since the time delay to develop a budworm from egg to L 2 can vary from 9 months to 2 years (Fleming and Shoemaker, 1992;Sheehan et al, 1989;Royama, 1984), we take τ with 0.75 ≤ τ ≤ 2. Since the normal survival rate of the immature population is given to be approximately 15% (Sheehan et al, 1989;Royama, 1984), we adjust the value of the immature mortality rated by using a formulad = ln(1/0.15)/τ .…”