Temperature-dependent development and survivorship of Idaea inquinata (Scopoli) (Lepidoptera Geometridae) eggs at two humidity levels

Idaea inquinata (Scopoli) mainly feeds on dried plants, nevertheless, it is also a potential pest of stored product as it is able to develop on cereal products. The few references on the biology of this species do not deal with the influence of temperature and relative humidity on egg hatching. To fill this gap, groups of 100 eggs, 24-48 hours old, were exposed to constant temperatures (13, 15, 36, and 38±1 °C), two relative humidities (35, 70±5%) and a photoperiod of 0:24 (Light:Dark); eight tests were carried out. Each test was replicated four times. The lowest proportion of hatched eggs was observed at 15 °C (9.5) and 36 °C (8.7) with 35±5% R.H. while at 13 and 38 °C eggs did not hatch. A non-linear function is used to represent the developmental rates and survivorship of eggs at 35 and 70% R.H. between lower and upper thresholds temperature.