Bioefficacy of some insecticides against tobacco caterpillar, Spodoptera litura (Fabricius) under lab conditions

The bioefficacy of five insecticides viz. Fipronil, Indoxacarb, Flubendiamide, Spinosad and Lambda cyhalothrin were conducted under lab condition by leaf dip method to determine their stomach toxicity against Spodoptera litura and the results revealed that at 24 HAE (hours after exposure) Indoxacarb (LC50 = 0.22 ppm) was the most toxic whereas Lambda cyhalothrin (LC50 = 350 ppm) was the least toxic and the order of toxicity was: Indoxacarb > Fipronil > Spinosad > Lambda cyhalothrin. Similar trends were observed at 48 HAE where the order of toxicity was Indoxacarb > Flubendiamide > Fipronil > Spinosad > Lambda cyhalothrin. The LC values indicated that Indoxacarb was most toxic (LC30 = 0.052 ppm; LC50 = 0.096 ppm; LC90 = 0.43 ppm) closely followed by Flubendiamide (LC30 = 0.3 ppm; LC50 = 0.8 ppm; LC90 = 7.2 ppm) whereas the least toxic insecticide was Lambda cyhalothrin (LC50 = 225 ppm). A comparative dose mortality response indicated in terms of relative toxicity (RT) indicated that at 72 HAE, Indoxacarb (RT 50 = 2960) was still the most toxic insecticide followed by Fipronil (RT 50 = 30.94) and Lambda cyhalothrin (RT 50 = 1.00).