The persistence toxicity of four insecticides against adult Hippodamia varigata (Coleptera: Cocinellidae).

: In order to investigate the effects of four insecticides on Hippodomia variegata (Coleoptera: Coccinellidae), the predator of Aphis fabae, an experiment was carried out using IOBC/wprs method. Persistence toxicity of insecticides has been evaluated in the greenhouse condition. The insecticides abamectin 1.8 EC, deltamethrin 2.5 EC, imidacloprid 350 SC, and proteus OD 110 were used at recommended field rates. The insecticides were applied on broad bean foliage using a hand sprayer, until run-off. Contact toxicity of aged residues of insecticides on adult predator was evaluated using the cage-method. The trials were laid out in randomized complete design (CRD) with 3 replicates and an untreated check. The arcsine transformation was used for analysis. The mortality of adult predator, after 24 h contact with fresh residues of abamectin, deltamethrin, imidacloprid and proteus were 53.4, 52.1, 63.4 and 65.1%, respectively. After 5 days the effect of residues decreased so that the adult mortality diminished to 32.4, 36.5, 56.1 and 57.5% for mentioned above insecticides. 15-day old residues lead to 8.8, 23.1, 56.3 and 57.5%; and 31-day old residues lead to 8.8, 22.7, 29.5 and 41.7% mortality for these insecticides, respectively. Based on this study, abamectin and deltamethrin with persistence less than 5 d are classified as short lived (Class A) while imidacloprid and proteus with persistence between 16 to 31d, classified as moderately persistent (Class C) compounds.