كليدواژه :
پايري پروكسي فن , روغن , زيست‌سنجى , سينرژيسم
چكيده فارسي :
چكیده
این آفت در برابر سموم شیمیایى به شدت از خود مقاومت نشان داده و از نظر كمّى و كیفى عملكرد پنبه را كاهش مىدهد. حشرهكشهاى مأنوس با محیط زیست به دلیل داشتن خصوصیات ویژه از جمله كمتر بر هم زدن محیط زیست حشرهكشهاى مطلوبى هستند، در این تحقیق حساسیت مراحل مختلف زیستى سفید بالك پنبه Bemisia tabaci نسبت به پایرىپروكسىفن، روغن سیتوویت و مخلوط آنها ارزیابى گردید. از روغن سیتوویت و پایرىپروكسىفن در پنج غلظت و تیمار شاهد استفاده شد. مقدار LC50 حشره‌كش پایرىپروكسىفن براى حشره كامل، تخم، مراحل نابالغ به ترتیب 1086، 0451/45 و4716/11 پىپىام تعیین گردید. LC50 روغن سیتوویت براى حشره كامل، تخم، مراحل نابالغ به ترتیب 1554، 7920/884 و 7002/684 پىپىام برآورد شد. به منظور ارزیابى نقش سینرژیستى روغن سیتوویت LC25 سم پا یرى پروكسىفن در هر مرحله زیستى با LC25 روغن سیتوویت مخلوط گردید كه در نتیجه میزان تلفات در حشره كامل، تخم و مراحل نابالغ به ترتیب 36/52% ،32/62% و 19/69% بدست آمد. و معلوم گردید كه روغن سیتوویت اثر پایرىپروكسىفن را تشدید مىكند.
چكيده لاتين :
Introduction: Bemisia tabaci is highly polyphagous herbivore. This is one of the most important cotton pests throughout the world. Bemisia tabaci causes noticeable damage to quality and quantity of cotton yield. Due to its special habitat, the present efforts to control of the pest have focused on the application of chemical insecticides. It is well established that the overuse and misuse of these compounds can lead to environemntal disasters and development of resistance. Therefore, undertakening research for a safe and environment- compatible method of control has been warranted. In our research, the degree of sensitivity of different life stages of B. tabaci to a juvenile hormone analogue compound and citowett oil was evaluated.
Materials and Methods: For this purpose, specimens were collected from contaminated tomato and tobacco flowerpots in the greenhouse of the Faculty of Agriculture at Urmia University. 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 which would cause 25-75 percent death rate. The main concentrations were calculated by the concentration of preliminary experiments.The control mortality was corrected using Abbott ʹs formula.
Results and Discussion: At the termination of experiments the following results were obtained: in all of the treatments, nymph, pupa and egg stages were the most sensitive ones to this compound, respectively, because the juvenile hormone analogue affected the egg and the immature stages but did not affect the adult insects. In the citowett oil treatment nymph, pupa and egg were the most sensitive stages and the adult insect was the most resistant one. The LC50 value of pyriproxyfen after 24 hours for the adult, egg, nymph along with pupa stages (immature stages) were 973.1530, 45.045 and 11.4468 ppm, respectively. The LC50 value of citowett oil after 24 hour for the adult, egg, nymph along with pupa stages were 2243.888, 884.5782 and 623.9682 ppm in the same order. When the basic equation y=a+bx was dotained for each life stage including adult, egg, nymph, pupa, LC25 of pyriproxyfen was counted up with LC25 of citowett oil for each life stage separately, then the pyriproxyfen with citowett oil mixture experiment was performed.The results of this experiment showed a 52.36% mortality rate for the adult, 62.32% response for the egg and 69.19% response for the nymph and pupa stages. These experiments revealed that the enhacement of pyriproxyfen toxicity when mixed with citowett oil. It can be argued that citowett oil has a synergistic effect on pyriproxyfen.In similar research the rate of LC50 pyriproxyfen for egg was 51 ppm and for the first instar nymphs was 18 ppm. This researchres also elucidated that first instar nymphs is the most sensitive of development stages and pupae have more tolerance in contrast of nymphs. Egg sensitivity is less than the other stages due to chorion layer. In a similar study Bemisia tabaci immature stages were more sensitive to pyriproxyfen than the other stages and it was concluded that the enfulence of pyriproxyfen even at low levels was effective on the immature stages.The LC50 of Citowett oil for adult, egg and immature stages of whitefly were reported 2580, 1310 and 250 ppm, respectively, that results of this study were different to the current researchdue to differences in insect biotype and historyof pest. To evaluate the effect of pyriproxyfen and oil mixture, LC25 of these compounds in the different stages were mixed.The mortality rate caused by mixing pyriproxyfen and citowett oil was further
Conclusions: These experiments demonstrated that because of the cheap price of citowett oil, in contrast to that of pyriproxyfen, a mixture of these compounds led to better control of Bemisia tabaci and is more economical.
