WEERAWANSHA, A.N.R.2021-04-082021-04-082011UWU/EAG/07/0039http://www.erepo.lib.uwu.ac.lk/bitstream/handle/123456789/6420/UWULD%20EAG%2007%200039-10052019103425.pdf?sequence=1&isAllowed=yA nursery trial for comparative efficacy of six insecticides; Methoxyfenozide 240EC, Spinosad 25EC, Tebufenozide 20F, Etofenoprox 10EC, Flubendiamide and Chlorpyrifos 40EC (the present recommended insecticide) at 10 mL, 15 mL, 10 mL, 10 mt., 4 g and 10 mL respectively per 100 L of water was carried out against Spodoptera litura in a commercial tobacco nursery. The experiment was laid out in Randomized Complete Block Design with seven treatments including the control and three replications where 10 caterpillars were introduced randomly to each treatment plot. All six insecticidal treatments were found significant indicating differential efficacy among themselves in reducing the larval population of Spodoptera litura at 1, 3, 5, 7, 9, 12 and 15 days following the application of the insecticides. Chlorpyriths, which was taken as the standard check and Methoxyfenozide were found to be superlative insecticides against Spodoptera litura recording a mean larval number of 1.667 and 1.333 respectively at seven days after application of insecticides. Spinosad was found to be a moderately toxic insecticide against tobacco cutworm recording ‘, 3.667 mean larval number. Flubendiamide also fairly succeeded to inflict mortality on the second instar larvae of Spodoptera litura which recorded 4.000 mean larval number at seventh day of application. Etofenoprox, and. Tebufenozide proved to be ineffective as it inflicted a low level of mortality. Methoxyfenozide was subjected to an insecticidal bioassay to find out its Median Lethal Concentration (LC50) against Spodoptera litura. LC50 was revealed as 0.6879 mL diluted in 1L of water.enExport Agriculture Degree Programme (EAG)Thesis