Screening of insecticides against pest complex of tomato and determination of terminal residues

Abstract

Bio-efficacy of indoxacarb 14.5 SC (0.005 %), k-cyhalothrin 5 EC (0.003 %), quinalphos 25 EC (0.05%), dimethoate 30 EC (0.03 %), spiromesifen 22.9 SC (0.028 %) and thiamethoxam 25 WG (0.008 %) was assessed against major pests viz; whitefly, Bemisia tabaci, leaf miner, Liriomyza trifolii, aphid, Aphis gossypii, fruit borer, Helicoverpa armigera and mite, Tetranychus urticae on tomato (cv. GT-2) under field condition in comparison to untreated control at Naysari Agricultural University, Naysari, Gujarat during Rabi 2017-18. Lowest whitefly (1.50/leaf) and aphid (0.36 grade) populations were observed in thiamethoxam 25 WG 0.008 per cent. Indoxacarb 14.5 SC 0.005 per cent treated plots showed lowest leaf minor damage (4.01 %) while, spiromesifen 22.9 SC 0.028 per cent proved most effective against mite (0.13). Indoxacarb 0.005 per cent was also proved most effective against H. armigera indicating lowest larval population (0.46), fruit damage (8.68 %) and highest yield (38.38 t/ha.). Indoxacarb 14.5 SC 0.005 per cent and dimethoate 30 EC 0.03 per cent were found most effective against all pests collectively while, A,--cyhalothrin 5 EC 0.003 per cent was found most economical (ICBR 1:8.39) followed by indoxacarb 0.005 per cent (1:6.87). Terminal residues of most effective insecticides (indoxacarb and dimethoate) were assessed under laboratory condition using QuEChERS method which indicated accurate (70 to 120 %) and precise recovery (< 20 %) and sensitivity (LOQ < MRL) for the determination of terminal residues of indoxacarb (0.101 .tg/g) and dimethoate (<LOQ, 0.02 µg/g) in tomato which were below MRL at harvest stage. So, it can be summarized that indoxacarb 14.5 SC 0.005 per cent and dimethoate 30 EC 0.03 per cent did not pose any residue problem when harvested on or after 7th day after application.