Impacts of six ethanolic plant extracts on feeding and developmental time of Tetranychus urticae

Development in chemical pesticides and the problems caused by the indiscriminate use of them, has led to the rise of new ways to control pests. The use of plant-based compounds is a proposed method, because they have far less destructive effects on the environment. Study of all aspects and effects of a botanical insecticide is required, such as feed rate which is assessed on Tetranychus urticae Koch. Individual leaves were sprayed with 6 ethanolic extracts (Aloe vera, Melia azedarach, Calendula officinalis, Syzygium aromaticum, Peganum harmala and Juglans regia) with concentration of 4 mg.mL−1, and then starved mites (larvae) were laid on them. Feeding rate was determined by the color of chlorophyll inside the body. Finally, M. azedarach, A. vera, P. harmala and C. officinalis decreased the feeding rate, specially M. azedarach extract caused almost 50% decrease in the first day, 30% in the second day and 20% in the third day. According to the last experiment, the mean of total developmental time of M. azedarach treatment was significantly longer than control treatment

TOXIC AND REPELLENT EFFECT OF HARMAL ( Peganum harmala L.) ACETONIC EXTRACT ON SEVERAL APHIDS AND Tribolium castaneum (HERBST)

To reduce the dependence on the sometimes unwise use of synthetic pesticides in fruit and vegetable plantations, the toxicity and repellence of Peganum harmala L. (Zygophyllaceae) acetonic seed extract was assayed against several insect pests. For contact toxicity, 3- to 4-d-old individuals of Aphis fabae Scopoli, A. gossypii Glover, A. nerii Boyer de Fonscolombe, and Myzus persicae (Sulzer) were included, as well as 1- to 7-d-old adult Tribolium castaneum (Herbst). Repellent effect experiments were conducted on adult, 1- to 2- and 3- to 4-d old M. persicae individuals. At 60 mg mL-1, the topical bioassay mortality percentage was significantly higher in A. gossypii than in A. fabae and A. nerii after 12-72 h. Mortality of the treatments on M. persicae was 87.1% and 90.0% after 24 and 48 h, respectively, and significantly higher than A. fabae and A. nerii during this period. At 60 mg mL-1, the mortality of T. castaneum was much lower than that of the aphid species. The highest repellent index (over 72%) was observed on 1- to 2-d-old M. persicae individuals