Pesticidal Effect of Leaves Extract of Different Plants on the Larvae of Cotton Leaf Worm, Spodoptera littoralis

Abstract

Background and Objective: The cotton leafworm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae), represents the worst lepidopterous pest on most vegetable crops. Moreover, its host range is extensive because it is a polyphagous and cosmopolitan pest that can cause an estimated loss of nearly 25.8 to 100% of crop production. Natural controls have replaced pesticides due to the environmental damage that chemical pesticides cause. Eggplant, tomato, okra and pepper are Egypt’s most significant vegetable crops and the leaves of these plants are cheap and can act as botanical and nontoxic pesticides. Materials and Methods: Spodoptera littoralis larvae were reared in the laboratory and plant leaves of eggplant, tomato, okra and pepper were extracted in the laboratory with organic solvents. Then, these extracts were applied to the larvae. Therefore, the histological sectors in larvae bodies were prepared and the changes were observed compared with the control. Results: This study proved the efficiency of all plant leaf extracts, especially those of eggplant and tomato leaves (LC50 of 1191.9 and 1582.7 ppm, respectively). In contrast, okra and pepper leaf extracts had the highest LC50 (3904.8 and 5431.6 ppm, respectively). Also, the abnormalities in the midgut and internal tissues were evident in the larvae treated with eggplant leaf extracts, followed by tomato leaf extracts and okra leaf extracts. Larvae treated with pepper leaf extracts were as normal as the control. Conclusion: The current study opens horizons to new plant extracts that are cheap and unused plant parts and make them helpful as new and good insecticides.