effects of melia azedarach l. and peganum harmala l. extracts on nymphal and pupal developmental duration of trialeurodes vaporariorum

background & aim: the plants of the greenhouse have been affected by infestation of the pest trialeurodes vaporariorum, called greenhouse whitefly, which markedly reduced production. synthetic insecticides have been widely developed and, their extensive use has brought about disadvantages, like environmental disturbance, pest resistance, lethal effects on non target organisms and toxicity to users and consumers. one alternative for control this invasive pest is the use of natural insecticides, active component isolated from the plants. green insecticides tend to have broad spectrum activity relatively specific in their mode of action and easy to process and use. the effects of methanolic extracts of melia azedarach l. and peganum harmala l. on nymphal and pupal developmental duration of t. vaporariorum investigated under laboratory condition. experimental: in both of the experiments, the leaf discs of bean plants with new hatched nymphs or pupae were placed into the round plastic petri-dishes (5 cm diameter) that filled with agar gel. the individuals of the nymph and pupa instars were treated with the concentration of m. azedarach and p. harmala extracts (80 mg/ml). in control group, water distilled was applied. results & discussion: the results indicate that the both methannolic extracts significantly increased nymphal developmental duration as compared to control. while, there was no significantly difference on pupal developmental duration in different treatments. the effect of plant extracts on nymphal developmental duration could be controlled on population dynamic of t. vaporariorum. also, they could be delayed immature stages of greenhouse whitefly. moreover, botanical pesticides appear to have potential as a good organic insecticide and provide for pest control an alternative to currently used pesticides. industrial and practical recommendations: according to this experiment, substituting conventional pesticides with methanol extracts of m. azedarach and p. harmala are an attractive prospect. however, formulating the plant extract is essential for commercial use of the botanical extracts. therefore, scientific studies on tech-biochemistry of the extract are necessary.