Study the toxicity effect of Urtica dioica stem and leaf extract on tobacco aphidMyzus nicotianae

Tobacco aphid (Myzus nicotianae) is one of the most important pests of tobacco and reduces the quality and quantity the tobacco product, directly and indirectly. Today, chemical insecticides are used to control pests. Due to the fact that plant extracts have a short shelf life in the environment and have low toxicity to humans, mammals and other living organisms, they are a good alternative to the side effects of chemical insecticides. In this study, the insecticidal properties of nettle Urtica dioica leaf and stem extracts on tobacco aphids were investigated. The experiments were performed at a temperature of 25 ±5° C, a relative humidity of 60±5% and a photoperiod of 16L: 8D. After extracting the aqueous extract of nettle by soaking method, for bioassay experiments, the 15 number of adults tobacco aphids were placed on filter paper and the lethal effect of mortality concentrations up to one percent in four replications on tobacco aphids were investigated. The lethal effect of these two extracts at 5 different concentrations (0.5, 1, 5, 10 and 15 mL/L) in four replications on the percentage of tobacco aphid mortality was investigated. The 50% lethal concentration (LC50) was calculated using the Probit program. The results showed that nettle leaf extract with (LC50 = 3.08 mL / L) showed more toxicity than nettle stem extract with (LC50 = 5.11 mL /L). The application of nettle leaf extract with a concentration of 15 mL / L after 48 hours caused 100% mortality on tobacco aphids, which is significantly higher than nettle stem extract (with 90% mortality). Overall, the results of this study showed that the extracts of both plant organs, especially nettle leaf extract, have good power to control tobacco aphids.