Susceptibility of Heliothis armigera (Hübner) eggs to different insecticides

Efficacy of nine insecticidcs, viz., endosulfan (0.07%), malathion (0.05%), quinalphos (0.05%), monoerotophos (0.04%), triazophos (0.04%), methomyl (0.025%), carbaryl (0.05%), fenvalerate (0.006%) and cypermethrin (0.006%) as ovicides was evaluated against eggs of Hetiothis armigera (Hubner) in the laboratory during 1999. Eggs of different ages, viz., 0–24, 24–48 and 48–72 hold were used in dipping method. The susceptibility of eggs to different insecticides varied with the age of the eggs, young egg (0–24 h old) being relatively more susceptible than the others. Much of the ovicidal action of different insecticides was recorded within the first 12 h after treatment and no additional mortality was observed 24 h after treatment. Irrespective of the age of eggs, overall mean egg mortality in different insecticidal treatments ranged from 56 to 86 per cent. The synthetic pyrethroids, viz., fenvalerate and cypermethrin, exhibited the highest egg mortality (>80%), followed by methomyl and triazophos (77% each). With the remaining five insecticides, viz., quinalphos, monocrotophos, endosulfan, malathion and carbaryl, the egg mortality was 72, 64, 62, 56 and 56 per cent, respectively.