Further advances toward a model of gypsy moth ( Lymantria dispar (L.)) egg phenology: Respiration rates and thermal responsiveness during diapause, and age-dependent developmental rates in postdiapause

Abstract

Measurements of respiration rates were used to support a three-phase model of gypsy moth egg development. Respiration rate was measured on individual eggs that had been reared for 0–155 days at 5 °C following diapause initiation. Diapause termination was indicated by the dramatic increase in respiration rate that began approximately 95–125 days after diapause initiation. Respiration rates at 25 °C increased each day by approximately 0.0054 μl CO 2/24 h during diapause. After diapause termination respiration rates increased each day approximately 0.1379 μl CO 2/24 h. Eggs were equally responsive to temperature changes during diapause and postdiapause. A 10 °C increase in temperature resulted in a 2-fold increase in respiration rate. Developmental rates in postdiapause were found to be age- and temperature-dependent. The initial developmental rate parameters and a temperature-dependent rate change parameter were estimated empirically and a composite function was derived to describe the age- and temperature-dependent behavior of the developmental rate response. Modeled rates increased from 0.0 and 0.078 day −1 at postdiapause initiation to 0.01 and 0.20 day −1 at physiological age 0.95, at 5 and 30 °C respectively.