فراسنجه‌های جدول زندگی باروری شته مومی‌، ‏brevicoryne brassicae‏ تحت تاثیر غلظت ‏زیرکشنده شته‌کش گیاهی بوتانافید روی دو رقم کلم

شته مومی‌کلم ‏brevicoryne brassicae l.‎‏ یکی از آفات مهم گیاهان تیره چلیپائیان در سطح جهان است که ‏خسارت قابل توجهی به گیاهان این خانواده وارد می‌کند. به دلیل آسیب‌های ناشی از استفاده بی‌رویّه از آفت‌کش‌های ‏شیمیایی، جستجوی روشی جایگزین برای کنترل این آفت نظیر استفاده از آفت‌کش‌های گیاهی ضروری به نظر می‌رسد. در ‏تحقیق حاضر، سمّیت حادّ حشره‌کش گیاهی بوتانافید روی شته مومی‌ در کلم سفید و قرمز تعیین شد و تاثیر غلظت ‏lc25‎‏ ‏به‌دست آمده روی هریک از رقم‌ها بر فراسنجه‌های جدول زندگی باروری این آفت ارزیابی شد. بر اساس نتایج زیست‌سنجی، ‏غلظت ‏lc50‎‏ این آفتکش روی شته مومی کلم در دو رقم سفید و قرمز به‌ترتیب برابر با 1.552 و 1.704 درصد به‌دست آمد. در ‏بررسی جدول زندگی با غلظت ‏lc25‎‏ (به‌ترتیب 0.675 و 0.765درصد در کلم سفید و قرمز) شته‌کش، میزان باروری هر فرد ‏ماده تیمار شده در هر دو رقم در مقایسه با شاهد (بدون حشره‌کش) کاهش یافت. به علاوه، تیمار حشره‌کش در هر دو رقم ‏کلم سفید و قرمز به‌ترتیب موجب کاهش 40 و 35.5 درصدی نرخ ذاتی افزایش جمعیت ‏‎(r)‎‏ شته مومی کلم نسبت به شاهد ‏متناظر شد. به‌علاوه، تیمار آفت‌کش موجب طولانی شدن معنی‌دار دوره زندگی آفت در مقایسه با شاهد شد. طبق نتایج، ‏حشره‌کش بوتانافید در هر دو رقم گیاه میزبان، باعث کاهش بقا و تولیدمثل شته مومی کلم در مقایسه با شاهد شد. در کنار این ‏نتایج، به‌دلیل ماهیت گیاهی بوتانافید و کم‌خطر بودن آن برای موجودات غیرهدف و به‌خصوص انسان، کاربرد این آفت‌کش ‏روی سبزیجات تازه‌خوری مانند انواع کلم قابل توصیه است.‏

fertility life table parameters of the cabbage aphid, brevicoryne brassicae ‎affected by sublethal concentration of botanaphid aphidicide on two ‎cabbage varieties

background and objectivescabbage aphid, brevicoryne brassicae l. is one of the important pests of brassicaceous plants ‎worldwide, causing considerable damage to them. it not only damages host plants by directly ‎sucking the tissue sap and excreting honeydew, but also transmits some plant pathogenic viruses ‎and further weakens the host crops. in one hand, due to the adverse effects of irregular chemical ‎pesticide use on vegetables such as cabbage, and indecisive effects of biocontrol agents in pest ‎control, exploring alternative methods for cabbage aphid management such as botanical pesticide ‎application sounds appropriate and necessary. therefore, in the present study, acute toxicity of the ‎botanical insecticide, botanaphid was studied against cabbage aphid on white and red cabbages by ‎determining their corresponding lc50 values. moreover, their sublethal (corresponding lc25 ‎values) effect was assessed on the fertility life table parameters of the pest in both white and red ‎cabbages.‎materials and methodsafter preliminary bioassays based on recommended concentration (2 % for cotton aphid) in both ‎plant cultivars, five concentrations were estimated by logarithmic intervals in white (0.45, 0.81, ‎‎1.48, 2.69 and 4.9 percent) and red (0.5, 0.89, 1.58, 2.82 and 5.01 percent) cabbages. control ‎aphids were treated with distilled water containing 0.05% citowett as surfactant. thirty newly ‎emerged adult aphids were randomly selected for each treatment. ten insects were placed on each ‎leaf disc and treated uniformly by a hand sprayer. after drying, insects were placed within petri ‎dish with ventilation. the number of dead insects were counted after 24 h. bioassay data were ‎analyzed by probit analysis using sas 24.0. to study the sublethal effects of botanaphid on ‎fertility life table parameters of b. brassicae, the calculated lc25 values (0.675 and 0.765 percents ‎respectively for white and red cabbage cultivars) of botanaphid were used. for each treatment and ‎control, 50 adult aphids were treated similar to bioassays. all treated insects were removed after 24 ‎h and the number of 50 newly emerged first instar nymphs from treated adults were randomly ‎selected and kept individually. the number of dead insects and produced nymphs were recorded ‎daily and removed from experimental units. life table data were analyzed using twosex-mschart ‎program and the means and standard errors of parameters were calculated by bootstrap method ‎using 100000 replicates.‎resultsaccording to the bioassays, the mean lethal concentrations (lc50 values) of this pesticide on ‎cabbage aphid were 1.552 and 1.704 percents respectively in white and red cabbages. in life table ‎study with lc25 values of aphicide, the lowest fertility and reproduction period of b. brassicae ‎were remarkably decreased on botanaphid treatment in both white and red cabbages compared to ‎corresponding control (insecticide-free) units. furthermore, pre-adult duration was prolonged and ‎survival of treated aphids was decreased considerably when compared to control. in addition, ‎insecticide treatment caused intrinsic rate of increase (r), as the most important population growth ‎parameter, of the cabbage aphids to be lowered significantly compared to corresponding control ‎insects. also, botanaphid sublethal concentration resulted in considerable decrease in other life ‎table parameters when compared to appropriate control insects in both cabbage cultivars. ‎reproduction values and life expectancies were the highest in control aphids and the lowest in ‎lc25-treated insects.‎discussionour results revealed that b. brassicae suffered considerable mortality from botanaphid, as a ‎botanical insecticide in nearly recommended concentrations (2 %). comparison of lc50 confidence ‎intervals (95%) showed that susceptibility of the pest was not statistically different in treated aphids ‎on white and red cultivars. this showed that the plant cultivar did not impose significant impact on ‎aphid mortality. given that the chemical content of sap and nutritional quality of two cultivars are ‎varying in different cultivars, these did not affect adult aphids’ mortality encountering botanaphid. ‎using lc25 value in each cultivar for analyzing life table parameters demonstrated the its negative ‎influence on all parameters compared to control insects in both cultivars. besides these results, due ‎to botanical nature of botanaphid and its low risk for non-target organisms especially human, this ‎pesticide application is recommendable on fresh-consuming vegetables such as different cabbage ‎cultivars.‎