Linear regression equations between the rates of development r(T) and temperature (15°C, 20°C, 25°C, 28°C or 30°C) to determine the base temperature (Tb) and thermal constant (K) for describing the nymph development of H. foeniculi.

1The base temperature or low development threshold (Tb) is calculated as Tb = −a/b.2The thermal constant, k (day-degrees) is calculated as k = 1/b. a is the intercept, and b is the regression line slope. The values of Tb and k were calculated for each instar and nymph stage (from hatching to the adult stage).