The current study investigated the toxicity of five insecticides, indoxacarb,
thiamethoxam+chlorantraniliprole, chlorantraniliprole, fipronil and lufenuron against
the 2 nd and the 4 th instar larvae of the cotton leafworm, Spodoptera littoralis using leaf-
dip bioassay under laboratory conditions. Based on the LC 50s values of the tested
insecticides for the 2 nd instar larvae of S. littoralis, the most toxic insecticide was
indoxacarb (0.009, 0.006 and 0.001 ppm), followed by thiamethoxam +
chlorantraniliprole (0.016, 0.01 and 0.009 ppm fold), chlorantraniliprole (0.21, 0.12 and
0.052 ppm fold), fipronil (3.79, 2.81 and 0.661 ppm fold) and lufenuron (5.19, 3.21 and
0.916 ppm fold) after 24, 48 and 72 hrs. post exposure, respectively. The toxicity index
and relative potency values showed indoxacarb was more toxic for the 2nd instar larvae
than thiamethoxam + chlorantraniliprole, chlorantraniliprole, fipronil and lufenuron by
(1.78, 23.33, 421.11 and 576.67), (1.67, 20.00, 468.33 and 535.0) and (9.0, 52.0, 661.0
and 916.0) fold, respectively. The 4 th instar larvae showed high susceptibility to
indoxacarb compared thiamethoxam + chlorantraniliprole, chlorantraniliprole, fipronil
and lufenuron. The LC 50s values of the tested insecticides revealed that indoxacarb was
more effective than other insecticides (0.83, 0.61 and 0.32 ppm), followed by
thiamethoxam + chlorantraniliprole (7.11, 5.23 and 1.11 ppm), fipronil (10.11, 9.13 and
3.26 ppm) and lufenuron (16.38, 14.39 and 4.11 ppm) after 24, 48 and 72 hrs. exposure,
respectively. Therefore, our study recommended using indoxacarb, thiamethoxam +
chlorantraniliprole and chlorantraniliprole in controlling CLW because of their mode of
action are different and promising for using these insecticides in Integrated Pest
Management programs.