Efficacy of the EC 1.28% formulation of Neem, Azadirachta indica, on two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae), in laboratory and field conditions

The acaricidal activity of new formulation of Neem EC 1.28% was compared with Neem Azal® (EC 1%) and spirodiclofen against the two-spotted spider mite, Tetranychus urticae Koch, under both laboratory and field conditions. The method of leaf dipping was used for bioassay experiments. The common bean leaves were dipped into different concentrations of treatments before exposing them to the adult mites from the same age. The mortality for mites was recorded after 24 hours. The experiment was conducted under 25 ± 2ºC, RH 60 ± 5 %, and 16: 8 (L: D) h photoperiod conditions. LC50 and related parameters were calculated, using POLO-PC software. The field studies were conducted in randomized complete block design with five treatments of 1 ml/l, 2 ml/l and 3 ml/l of EC 1.28% formulation, 0.5 ml/l spirodiclofen and 1 ml/l of Neem Azal®. Plain water was used for the control group. The LC50 values for Neem Azal®, spirodiclofen and Neem EC 1.28% formulation were 52.04 mg/l, 37.55 mg/l and 21.06 mg/l, respectively. The results showed that mites were more susceptible to the new EC 1.28% formulation. In the field, spirodiclofen was found to be the most effective compound after 3 and 7 days of treatment causing 89.3 ± 1.7% and 77.8 ± 2.3% mortality, while Neem Azal® was less effective with 64.40 ± 4.04% and 68.7 ± 2.9% mortality on mites. The new EC 1.28% formulation was used at the rate of 3 ml/l, which caused 82.8 ± 2.4% and 70.2 ± 3.9% mortality, without significant difference with spirodiclofen treatment.