Toxicity effect of henna, Lawsonia inermis L. and madder Rubia tinctorum L. extracts on Rhopalosiphum padi L. versus pesticidal effect of pirimicarb and imidacloprid

Rhopalosiphum padi L. (Hem.: Aphididae) is one of the most important pests damaging cereals specially wheat and lowering the quality and quantity of the production directly and indirectly each year. In this study, the toxicity effect of two extracts of Rubia tinctorum L. (Rubiaceae) and Lawsonia inermis L. (Lythraceae) is compared with two conventional insecticides, imidacloperid and pirimicarb. The study was conducted in petri dish of 8 centimeter diameter using a completely randomized design with five different concentrations for each set with four repetitions on 15 adult insects of R. padi L. (Hem.: Aphididae) 25±2 degree Celsius, relative humidity of 70±5 percent and in photoperiodic of 16 hours lightness and 8 hours darkness. All biometric studies were performed on similar and identical leaves of barley with the method of leaf immersion. The number of dead insects was counted after 24 hours. The results indicated that the insecticide imidaclorperide with fatal effects of 50%, 0.0318 and the methanol extract of henna L. inermis L. with fatal effects of 469.532 micro liter per milliliter were the most and least effective, respectively. Comparison of the results revealed that the extracts of the two plants, especially methanol extract of madder (R. tinctorum L.) with insecticide imidaclorperide and pirimicarb, have especial toxic potential to control the above said insect. Accordingly, as the extracts had less potential insecticidal potential, they should be used in conjunction with other methods.