A mechanistic model was developed. to simulate apple orchard populations of the pine vole (Microtus pinetorum) in southwest Virginia. Population. size and demographic parameters were modeled on a weekly basis as functions of bioenerqetic status. Forage gross energy availability, digestibility, palatability, and preference were functions of Julian day. Daily energy budget (DEB) was a function of age, reproductive status, body weight, ambient temperature, and daily activity level. Energy acquisition was simulated assuming that consumption exceeded neither dietary energy demand nor a known maximum ingestion rate, and using linear programming to allocate forage class gross energy among competing vole classes. The 5 forage classes were queued by preference and consumed until all voles had fed maximally or forage was exhausted. Body weight and fat change were functions of age and energy restriction. Survivorship was a function of body fat balance, and probabilities of reproduction were functions of body fat balance and photoperiod. Animals were graduated between age and reproductive classes in a modified. Leslie algorithm by independent Bernoulli trial to avoid simulating fractional animals.

Validation simulations suggested that dietary energy availability may limit pine vole populations in abandoned apple orchards, but not in maintained orchards. Simulation experiments suggested that pest populations of the pine vole in commercially maintained orchards may be controlled by a single control application in the fall achieving 80% mortality, or by 2 applications in the fall and spring achieving 50% mortality each.