Improvement of expired insecticides and their effectiveness against the cotton leafworm, Spodoptera littoralis (Boisd.)

Objectives: This study aimed to recycle some expired insecticides and evaluate their effectiveness against the cotton leaf worm, Spodoptera littoralis (Boisd.) as a tactic to dispose of these obsolete insecticides. Methods: The physical and chemical characteristics of chlorpyrifos (Chlorzane 48% EC), malathion (Nasrlathion 57% EC) and cyhalothrin (Lambda-cyhalothrin 5% EC) insecticides were determined. The active ingredients of the tested compounds were estimated by gas-liquid chromatography (GLC) equipped with a flame photometric detector GC/FPD and the insecticidal efficacy against the 4th instar larvae of the cotton leafworm, S. littoralis (Boisd.) was evaluated by the leaf dipping technique. Results: The physical and chemical characteristics of the tested insecticides clarified that chlorpyrifos (Chlorzane 48% EC) succeeded in the stability of emulsion, while cyhalothrin (Lambda-cyhalothrin 5% EC) and malathion (Nasr-lathion 57% EC) failed the test, whether unexpired or expired. The emulsifiers, Tween 80 or Triton X-100 at a concentration of 20%, managed to improve the characterizations of the expired insecticides, cyhalothrin and malathion. Moreover, these emulsifiers investigated a promising increase in the efficiency of expired cyhalothrin against S. littoralis. Conclusions: The emulsifiers, Tween 80 or Triton X-100 could be used to increase the efficiency of expired insecticides, especially cyhalothrin 5% EC, thus managing to apply and dispose of that outdated insecticide. (c) 2021 The Authors. Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).