Embryonic and larval development of Orthosia (Lep., Noctuidae) species used for optimizing timing of monitoring and control in apple orchards

Abstract

Abstract: Three Orthosia species were studied to forecast larval emergence and development and to find out the optimal moments for monitoring and control. The duration of embryonic and larval development of Orthosia incerta and Orthosia stabiliz was determined at various constant temperatures, and validated in field experiments. Embryonic development of Orthosia gothica was followed in the field. No significant differences between embryonic development of the species under study were observed. The estimated heat sum for embryonic development is 72 degree days above a developmental threshold of 7.0°C. Differences in development of the first larval stage depending on the quality of the substrate were found for O. incerta. Stage one of this species developed faster on artificial food than on fresh apple leaves, but total larval development rates of the species observed showed hardly any difference. The regression equation Y = 0.0017 × T – 0.0045 gives a good description of the total larval development rate (L1‐pupa) for both species. The larval development rates were implemented in an age‐structured phenological computer model INSIM. Results of simulations were in close agreement with field observations. Opportunities for use of these data in practice are discussed.