Thermal Requirements and Life Table Parameters of Tomato Leaf Miner Tuta absoluta (Lepidoptera: Gelechiidae) in Egypt

Abstract

Background and Objective: The tomato leaf miner, Tuta absoluta (Meyrick) is being a serious pest to tomato cultivations in Egypt since 2009. The present study was carried out to calculate the developmental parameters of insects based on temperature degree. Materials and Methods: The influence of 3 tested temperatures (20, 24, 28EC) were examined to evaluate its effect on the developmental stages of T. absoluta. Developmental thresholds and needed heat units for insect stages were mathematically calculated according to developmental rates. Results: Developmental threshold for egg stage and mean thermal units were calculated to be 7EC and 86.2 DD's. The developmental threshold for the larval stage was 10EC, while mean thermal units were calculated to be 310.8 DD's. Percentages mortality of larval stage were 52, 74, 74 and 100% at 20, 24, 28 and 32EC, respectively. For the pupal stage developmental threshold and mean thermal units required for completing the pupal stage was 11.2EC and 132.2 DD's. For an adult, zero of the developmental threshold female and of male were 11.2 and 9.8EC, respectively. The mean required heat units for female and male was 142.3 and 136.7 DD's Life table parameters such as net Reproduction Rate (RN), Mean Generation Time (Gt), Intrinsic Rate of Increase (rm), Finite Rate of Increase (λ) and Population Double Time (Dt) were calculated at three tested temperatures. Conclusion: Estimating thermal heat units of T. absoluta help in predicting the field generations of the insect and improve planning the integrated pest management.