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 (<i>Tb</i>) and thermal constant (<i>K</i>) for describing the nymph development of <i>H. foeniculi</i>.

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