The effect of botanical insecticides Palizin® and Tondexir® on cabbage waxy aphid, Brevicoryne brassicae L. under laboratory conditions

Canola Brassica napus L. (Brassicaceae) is a plant with oil-rich seeds; grown worldwide. The cabbage aphid, Brevicoryne brassicae L. is one of the most important pests of Canola crops. Considering the importance of human health and environmental protection, the reduction of using the chemical pesticides in the pest control program is essential. Therefore, the sub-lethal effect of Palizine® and Tandaxir® plant insecticides on the life table parameters of cabbage aphid was investigated using the aphid leaf immersion method Besides, the toxicity of insecticides was studied on the first nymphal instar of cabbage aphid.

First, preliminary experiments were conducted to determine the concentration range. After determining the highest and lowest concentrations, the middle concentration was selected. Six concentrations and one control were selected for each insecticide. After determining the concentration in the preliminary experiment, the leaf discs (5 cm in diameter) including aphids (first nymphal stage) were immersed in the different concentrations of insecticides for 5 seconds. The leaf discs to be treated were then dried, covered with an organza net, and placed under natural laboratory conditions for one hour. Distilled water and Tween 80 were used as control treatments. To investigate the sub-lethal effect of insecticides on aphids, the concentrations of 1843.99, and 1627.02 mg / L (LC30) were used for Tandaxir® and Palizin®, respectively. The experiments were performed at 25±5oC, 60%±5% RH and 16: 8 (L: D) photoperiod on canola seedlings, B. napus.

The levels of LC50, Tondaxir®, and Palizine® were estimated to be 2331.52 and 2190.60 mg / L, respectively. The intrinsic rate of increased population (r) were 0.27±0.003 for control, 0.21±0.008 for Palizin® and 0.2±0.007b for Tondexir®. Net fecundity rate of decreased population in both insecticide.Net reproduction rate and intrinsic reproduction rate decreased in both insecticide treatments compared to the control treatment. A relative increase in the intrinsic mortality rate of insecticide-treated aphids was observed. The mean production time and doubling time were also lower in the population treated with the insecticides than the control group. There was a significant decrease in the average number of nymphs produced per female aphid; compared to control group. The mean lifespan of adult females in control group was significantly different from the insecticide treatments. All LC30 aphid-treated table statistics were negatively affected compared to control group.

Conclusion  :                                               

Due to the results, these two insecticides are toxic to cabbage wax aphids even at low concentrations and suppress the population of this pest. The present study can be a step towards the practical use of plant compounds and as a suitable alternative to chemical insecticides. By conducting the additional experiments, these plant compounds can be used to control cabbage wax aphids in the field.