Egyptian Cotton Leafworm: Laboratory and Field Evaluation of Certain Insecticides1

Abstract

Forty-one insecticides and combinations in different formulations and rates were screened for their effectiveness against Spodoptera littoralis (Boisduval ) as ovicides and larvicides; 23 compounds and combinations, mostly organophosphorous insecticides, induced complete ovicidal or early larvicidal effect within 48 h after they were sprayed under field conditions, but they lacked persistance as ovicides. The most effective initial ovicides according to rates of active ingredients were: chlorpyrifos, Cyolane ® 25% (cyclic ethylene P, P -diethyl phosphonodithiomidocarbnmate) Cytrolane® 25%, (cyclic propylene P, P diethyl phosphonodithioimidocarbonate) chlordimeform, monocrotophos, and methomyl. The most effective group of larvicides against all instars under field conditions were Bayer 5638, ( O, O -diethyl- O -(3-quinoxalyl) phosphorothioate), chlorpyrifos, dicrotophos, endrin + leptophos (1:1), leptophos EC, methomyl, monocrotophos, Tamaron® ( O -methyl S-methyl phosphoamidothioate), the mixture of toxaphene + DDT + methyl parathion, and phoxim. The foliage residues of most sprayed compounds after 5 days showed loss of more than 50% of their residual toxicity agninst different larval instars under laboratory conditions. The compounds which gave more than 50% larvae mortnlity were after 5 days: monocrotophos, Bayer 5638, Cyolane, Cytrolane, endrin + dicrotophos, endrin + leptophos (1:1), leptophos EC, Tamaron, and phoxim.