Effect of some insecticides on Tuta absoluta (Lep.: Gelechiidae) and Trichogramma brassicae and

Effect of some insecticides on Tuta absoluta (Lep.: Gelechiidae) and Trichogramma brassicae and T. evanescens (Hym.: Trichogrammatidae) under Laboratory Conditions

Sedighe Ashtari, Qodratollah Sabahi* and Khalil Talebi Jahromi
Department of plant protection, University of Tehran, Karaj, Iran, aroya95@gmail.com, qodratsabahi@gmail.com,
khtalebij@gmail.com
Tomato leaf miner, Tuta absoluta (Meyrick) is one of the most destructive pests of tomato in the world. In current study, the effects of insecticides of abamectin, emamectin benzoate, acetamiprid and flubendiamide were studied against 1st larval instar and pupae of tomato leaf miner and adult stage of Trichogramma brassicae and T. evanescens. Rearing of the pest was carried out at 25±۱°C, 65±۱۰% RH and a photoperiod of 16:8 h (L: D). The stock population of each parasitoid was reared separately on the eggs of the factitious host, Sitotroga cerealella (Lepidoptera: Pyralidae) under laboratory conditions. The larvae and pupae of leaf miner were treated by leaf dipping method however coated vial residue method was used for parasitoids treatment. Each concentration included three replications and there were 20 larvae or 15-20 pupae of pest or 20 adult of each species of parasitoid for each replication. Treatments consisted of five concentrations for each insecticide and one for control. Insect mortality was recorded 24 h after initial exposure. The LC50 value of abamectin, emamectin benzoate, acetamiprid and flubendiamide for 1st larval instar was 0.92, 0.13, 1.51 and 0.34 mg /l and for pupae was 4.99, 2.25, 3.22 and 3.48 mg /l, respectively. The LC50 value of abamectin, emamectin benzoate, acetamiprid and flubendiamide for Trichogramma brassicae was 0.0013, 0.0029, 0.0058, 1.53 and for T. evanescens 0.0014, 0.0025, 0.0052, 1.71 mg /l respectively. Results showed that emamectin benzoat was the most toxic compound against 1st instars larvae or pupae compared to other insecticides which amongst them only flubendiamide was found to be harmless to both parasitoids.
Keywords: Bioassay, dipping, LC50, vial