بررسی اثرات کشندگی حشره‌کش اسپیروتترامات، روغن سیتووت و مخلوط آن‌ها علیه آفت سفید بالک (bemisia tabaci) روی گوجه‌فرنگی در شرایط گلخانه

گوجه‌فرنگی نقش مهمی در اقتصاد گلخانه‌داران دارد. سفیدبالک (bemisia tabaci gennadius.) یکی از مهمترین آفات محصولات گلخانه‌ای کشور است که از آفات کلیدی گوجه‌فرنگی نیز به‌شمار می‌رود. یکی از متداول‌ترین روش‌های کنترل این آفت، استفاده از آفت‌کش‌ها می‌باشد ولی عوامل زیستی مختلف مانند دامنه وسیع میزبانی، چند نسلی بودن، نرخ بالای تولیدمثل، توانایی انتقال ویروس‌های گیاهی و گسترش مقاومت به حشره‌کش‌ها باعث مشکلاتی در مدیریت این آفت شده است. بنابراین استفاده از حشره‌کش‌های جدید جهت کنترل این آفت ضروری به‌نظر می‌رسد. در این پژوهش حساسیت مراحل مختلف زیستى سفیدبالک جالیز bemisia tabaci نسبت به اسپیروتترامات، روغن سیتووت و مخلوط آن‌ها مورد ارزیابی قرار گرفت. از روغن سیتووت و اسپیروتترامات در پنج غلظت و شاهد استفاده شد. مقدار lc50 حشره‌کش اسپیروتترامات براى حشره‌ی بالغ، تخم، مراحل نابالغ به‌ترتیب 5.53، 60.10 و1.46 پى‏پى‏ام تعیین گردید. lc50 روغن سیتووت براى حشره‌ی بالغ، تخم، مراحل نابالغ به‌ترتیب 1743، 977.62 و 728.36 پى‏پى‏ام برآورد شد. اسپیروتترامات و روغن سیتووت اثر بیشتری روی مراحل نابالغ نسبت به سایر مراحل داشتند. به‌منظور ارزیابى نقش سینرژیستى روغن سیتووت lc25 اسپیروتترامات در هر مرحله زیستى باlc25 روغن سیتووت مخلوط گردید که در نتیجه میزان تلفات در حشره‏ بالغ، تخم و مراحل نابالغ به‌ترتیب 54.77، 61.55 و 68.65 درصد به‌دست آمد و مشخص گردید روغن سیتووت اثر اسپیروتترامات را تشدید مى‏کند. با توجه به قیمت کمتر روغن سیتووت نسبت به اسپیروتترامات، تاثیر افزایشی آن بر حشره‌کش و همچنین سازگاری بیشتر این روغن با محیط زیست، استفاده از مخلوط آن‌ها برای کنترل این آفت قابل‌توصیه می‌باشد.

Investigation of lethal effects of spirotetramat, citowett oil and their mixture against Bemisia tabaci on tomato in greenhouse conditions.

Introduction: Bemisia tabaci is known in Iran and many other countries as a firstclass Cotton pest. This pest is one of the most important pests of Tomatoes in greenhouses as well as other crops, summer crops and greenhouses in most parts of the world, especially in hot, temperate, and dry regions of the world. Due to the high damage caused by this pest, Tomato greenhouses are frequently sprayed during the growing season. Materials and Methods: Plastic pots with a diameter of 18 and a height of 18 cm were selected. Tomato seeds were planted in pots. After the Tomato plants sprouted, the weak plants were removed from the pots. For immature preparation, large numbers of adult insects were released on Tomato pots and observed on the leaves four weeks after release of all biological stages. To prepare the eggs, large numbers of white cotton bulb insects were released on tomato plants planted in pots. For this purpose specimens were collected from contaminated Tomato flowerpots. After immersion of leaves in the pesticide solutions, the sensitivity of different life stages was evaluated. The purpose of this test is to determine the range of concentrations of insecticides that had been led to 2575 percent of death. The main concentrations were calculated by the concentration of preliminary experiments. Likewise, control mortality was corrected using Abbott’s formula. Results and Discussion: The results of this study, according to the average lethal concentration of 50 percent of the insecticide Spirotetramat showed that this insecticide was evaluated toxic for immature, adult and eggs, respectively. Since spirotetramat is a systemic insecticide and also feeds the adult and immature stages of this pest, adult and immature stages are more sensitive than eggs. The reason for the less susceptibility of eggs to this insecticide is the presence of an impermeable layer of chorion. Due to the way spirotetramat works, it especially affects the immature stages of sucking pests. In the case of adult female insects, this compound significantly reduces fertility and reproduction, resulting in a decrease in insect population. Gulen et al. investigated the crossresistance and susceptibility of Western flower thrips to spirotetramat in vitro on bean pods and reported that spirotetramat was more toxic to the nymph stages of the insect tested (Guillen et al., 2014). The results of this study are similar to the results of the present study in terms of the greater effect of spirotetramat on the immature stage (Gaskin et al., 2010) in field experiments reported that the addition of an oil and dispersant to the insecticide spirotetramat had a good effect on controlling oysters. These oysters are generally very difficult to control due to the hard shell of the insect because insecticide alone cannot penetrate. The results of this study are similar to the results of the present study, which shows the increased effect of spirotramat by citowett oil.Bioassay with citowett oil showed that immature stages and eggs were more sensitive than adult insects. Which can be due to the contact toxicity of the oil. To evaluate the effect of spirotetramat and citowett oil insecticide mixture, their LC25 doses were mixed and the effect was determined on different stages and the resulting mortality rate was determined. The mortality rate due to the mixture of LC25, insecticide spirotetramate and citutot oil was higher than the total expected losses (50%), 4.77% in adult insects, 11.55% in egg stage and 18.65% in immature stage. The increase in lethality after adding oil to the insecticide is consistent with the results obtained by some researchers (Ashtari, 2019; Ashtari et al., 2020; Hosseini Naveh et al., 2010). Conclusions: Based on the results of the study and the studies of other researchers, it can be concluded that the whitetailed deer, due to its special biological and behavioral conditions, has a high potential for resistance to most toxins. Applying proper management principles to control the mass of its population should be done. The issue of the phenomenon of resistance to toxins has accelerated in it.