Nawal Abdulaziz Alfuhaid1, Rania M. A. Helmy2, El-desoky S. Ibrahim3, Moataz A.M. Moustafa3*
1Department of Biology, College of Science and Humanities, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia
2Pesticide Residues and Environmental Pollution Department, Central Agricultural Pesticide Laboratory, Agricultural Research Center, Dokki, Giza 12618, Egypt
3Department of Economic Entomology and Pesticides, Faculty of Agriculture, Cairo University, Giza 12613, Egypt
*Corresponding author’s email: moat_mon@agr.cu.edu.eg
Received: 03 May 2025 / Accepted: 20 August 2025 / Published Online: 27 August 2025
Abstract
Onion (Allium cepa L.) is a globally significant vegetable crop that is frequently targeted by various insect pests including the onion thrips, Thrips tabaci Lindeman. This study evaluated the efficacy of three insecticides – dinotefuran, flonicamid, and flometoquin – against adult T. tabaci on onion using two application methods: drip chemigation and foliar application. Additionally, the study assessed residues of the three insecticides in green onions and onion bulbs, as well as plant growth and productivity response to the insecticides. The results showed that flometoquin, flonicamid and dinotefuran have effectively controlled A. cepa infestations after foliar application. However, flometoquin chemigation maintained effective control for 45 days after application. The findings indicated that the tested insecticides did not significantly impact plant height or leaf number; however, the foliar application of flometoquin resulted in the highest mean bulb weight and overall crop yield per m2, while the drip chemigation method produced the highest chloroplast density in plant cells. Flonicamid and dinotefuran exhibited prolonged persistence with residues detectable up to 45 d post-chemigation. Additionally, High-Performance Liquid Chromatography (HPLC) was used as the primary technique for residue determination of flonicamid, flometoquin and dinotefuran with retention time 3.8, 4.54 and 4.9 min. the LOQ of tested pesticides were 0.1 mg/kg. While Maximum Residue Limit (MRL) of flonicamid, flometoquin and dinotefuran was 0.03, 0.05 and 0.1 mg/kg. The half-lives of flonicamid were 2.28 and 4.16 d and the pre-harvest intervals (PHI) were 5 and 10 d for spraying and chemigation, respectively. Flometoquin had a half-life of 3.03 d after spraying, with a PHI of 10 d. Dinotefuran’s half-lives were 3.34 and 2.17 d, with PHIs of 15 and 10 d in green onions following spraying and chemigation, respectively. Our results suggest that drip chemigation with dinotefuran and flonicamid represents a promising and cost-effective strategy for the sustainable management of onion thrips.
Keywords: Onion thrips, Insecticide efficacy, Foliar application, Drip chemigation, Insecticide residue
