تاثیر ترکیبات مختلف آلی و شیمیایی روی تراکم جمعیت سفیدبالک گلخانه و برخی ترکیبات ثانویه گیاه لوبیا

سفیدبالک گلخانه،trialeurodes vaporariorum westwood  یکی از آفات مهم گیاه لوبیای معمولی است. در این تحقیق تاثیر برخی ترکیبات آلی شامل عصاره متانولی پوست گردو (mw)، عصاره ان­هگزانی پوست گردو (nw)، عصاره متانولی دانه شوید (md)، عصاره ان­هگزانی دانه شوید(nd)  و اسید سالیسیلیک (sa)، به تنهایی و در ترکیب با آفتکش اسپیروتترامات (sp) روی سفیدبالک گلخانه و برخی ترکیبات شیمیایی ثانویه گیاه لوبیا بررسی شد. آزمایش­ها در شرایط گلخانه با محلول­پاشی تیمارهای مورد بررسی روی گیاهان لوبیا انجام شد. نتایج تحقیق نشان داد که تراکم جمعیت سفیدبالک گلخانه و ترکیبات شیمیایی ثانویه گیاه به طور معنی­داری تحت تاثیر تیمارهای آزمایشی بود. میزان فنل کل در تیمارهای مختلف بین 58/96 تا 114/07 میلی­گرم بر گرم وزن خشک متغیر بود که بیش­ترین و کم­ترین مقدار آن به­ترتیب در تیمارهای ترکیب اسپیروتترامات با عصاره متانولی دانه شوید و ترکیب اسپیروتترامات با عصاره ان­هگزانی پوست گردو به­دست آمد. بیش­ترین مقدار فلاونوئید کل گیاه لوبیا نیز در تیمار ترکیب اسپیروتترامات با اسید سالیسیلیک بود. نتایج تحقیق حاضر نشان داد که تراکم جمعیت سفیدبالک گلخانه در تیمار اسپیروتترامات به تنهایی کم­تر از سایر تیمارها بود اما اختلاف معنی‌داری نیز با تیمارهای تلفیقی و تیمار عصاره متانولی پوست گردو نداشت. همچنین همه تیمارهای مورد مطالعه در مقایسه با شاهد به­طور قابل توجهی موجب تغییر تراکم جمعیت این آفت و افزایش مقدار فنل کل گیاه لوبیا شدند. بنابراین می­توان از این ترکیبات بویژه عصاره متانولی پوست گردو در برنامه­های مدیریت تلفیقی این آفت استفاده نمود.

Effect of Different Organic and Chemical Compounds on Population Density of Trialeurodes vaporariorum Westwood and Some Secondary Metabolites of Bean Plant

Introduction: Greenhouse whitefly, Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae), is a serious pest of a wide range of plants, such as common bean, cucumber, tomato, pepper, lettuce, etc, in both field and greenhouse production. It typically feeds on the underside of leaves, sucking phloem sap from the plant, which causes both direct damage, by overall weakening the plant and reducing yield, and indirect damage, by excreting honeydew, on which sooty mold grows, as well as transmission of several plant viruses. The widespread use of insecticides to control T. vaporariorum has resulted in developing resistance to the insecticides and affected human’s health and safety. The utilization of plant extract and elicitors is an environmentally safe method that is used in the control recently. Therefore, alternative control strategies are required to minimize the harmful effects of insecticides. In order to control this pest, environmentally friendly methods, especially of plant origin are recently considered by researchers. For this regard, the effect of some organic compounds including methanolic and nhexanic extract of walnut’s husk or dill’s seeds and salicylic acid, individually and in combination with spirotetramat on population density of greenhouse whitefly’s nymphs and some secondary compounds of bean plant were investigated.Materials and Methods: Seeds of common bean, Phaseolus vulgaris L. (Berloty cultivar) were sown and grown in 15cmplastic pots in a greenhouse at 25 ± 3°C, 50 ± 10% RH, and a natural photoperiod. For the experiments, potted bean plants at 68 leaf stage, highly infested with T. vaporariorum nymphs, were sprayed with 12 different treatments, including: (1) spirotetramat (SP), (2) methanolic extract of walnut husk (MW), (3) nhexanic extract of walnut husk (NW), (4) methanolic extract of dill seed (MD), (5) nhexanic extract of dill seed (ND, (6) salicylic acid (SA), (7) spirotetramat in combination with salicylic acid (SP+SA), (8) spirotetramat in combination with methanolic extract of dill seed (SP+MD), (9) spirotetramat in combination with methanolic extract of walnut husk (SP+MW), (10) spirotetramat in combination with nhexanic extract of dill seed (SP+ND), (11) spirotetramat in combination with nhexanic extract of walnut husk (SP+NW), and (12) water as a control (CO). After five days, the population density of T. vaporariorum nymphs on bean plants leaves was recorded. Furthermore, the effects of tested treatments on the total phenol and flavonoid contents of bean plants were evaluated. For this reason, dried leaves (5 g) from each treatment were used for the preparation of extracts. The total phenolic of the extracts were determined using the Folin Ciocalteu reagent. Sample and standard readings were made using a spectrophotometer (Lambda 45UV/Visible) at 765 nm against the reagent blank. Furthermore, the aluminum chloride colorimetric method was used for determination of the total flavonoid content of treatments. For total flavonoid determination, quercetin was used to make the standard calibration curve. The absorbance was read using a spectrophotometer (Lambda 45UV/Visible) in the wavelengths of 415 nm. Data were analyzed by oneway ANOVA using SPSS 23.0 software. Comparison of means for nymph density using SNK (StudentNewmanKeuls) multirange test and comparison of means for secondary chemical compositions using Tukey’s test at probability level five Percentage occurred.Results and Discussion: Results showed that the population density of greenhouse whitefly and the secondary metabolites of plant were significantly affected by the tested treatments. The lowest number of whitefly’s nymphs was on spirotetramat and spirotetramat in combination with methanolic extract of dill seed and the highest number was on control. Total phenolic contents ranged from 58.96 to 114.07 mg g1 dry weight on different treatments, which the highest and lowest amount of it was obtained in spirotetramat in combination with methanolic extract of dill seed and spirotetramat in combination with nhexanic extract of walnut husk, respectively. The highest amount of total flavonoid content of bean plants was in spirotetramat in combination with salicylic acid. The results of the present study showed that the density of greenhouse whitefly population in spirotetramate treatment was lower than other treatments but there was no significant difference with the combined treatments and methanolic extract of walnut husk. Also, all the treatments compared to the control significantly changed the population density of this pest and increased the amount of total phenolic compound in bean plant. Therefore, these compounds, especially the methanolic extract of walnut husk, can be used in integrated management programs of this pest.Conclusion: This research could provide valuable information for control of T. vaporariorum in other plants like ornamental plants in the field and greenhouse and thus can be useful for the production of healthy and organic crops. So it can be used in the IPM programs of this pest.