Development of rusty wave Idaea inquinata at constant temperatures, relative humidities and photoperiod

The development of larvae and pupae of Idaea inquinata was studied at two different temperatures, relative humidities and photoperiods. Tests were carried out at 26±1°C and 29±1°C, 50±5% RH and 70±5% RH, photoperiod 16:8 and 0:24 (light:dark). The highest mortality was observed at 29°C, with 50 and 70% RH and a photoperiod of 16:8. The larval development was longest (64 days) at 26 and 29±1 °C, 50±5% RH and the photoperiod 16:8, and shortest (23 days) at 29±1 °C, 50 and 70±5% RH, and the 0:24 photoperiod. The analysis of the mean lengths of the development of larvae at different temperatures and relative humidity with the 16:8 photoperiod showed that the developmental time of larvae decreases with increasing relative humidity. This factor was significant, while the effect of the increase of temperature and the interaction between the temperature and relative humidity was not significant. At a 0:24 photoperiod a decrease of the developmental time of larvae was observed when temperature was increased, both at 50 and at 70% RH. The developmental time of pupae was between 4 and 15 days, the shortest mean developmental time with a highest number of alive individuals was observed at 29±1 °C, and the photoperiod of 0:24, and both levels of relative humidity. The pupal developmental time showed small differences at the two relative humidities, with the exception of 26±1 °C and photoperiod 16:8: at 50±5 % RH where the mean development time was 10.7 days (±1.3 SD), and at 70±5 % RH with mean duration of 9.1 days (±1.6 SD). The photoperiod influenced the length of development in I. inquinata as the shortest mean development periods were observed in the tests carried out with photoperiod (0:24).