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, 28°C) 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 7°C and 86.2 DD's. The developmental threshold for the larval stage was 10°C, 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 32°C, respectively. For the pupal stage developmental threshold and mean thermal units required for completing the pupal stage was 11.2°C and 132.2 DD's. For an adult, zero of the developmental threshold female and of male were 11.2 and 9.8°C, 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 (R<inf>°</inf>), Mean Generation Time (Gt), Intrinsic Rate of Increase (r<inf>m</inf>), 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.