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نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه گیاهپزشکی، دانشکدگان کشاورزی و منابع طبیعی دانشگاه تهران، کرج، ایران
2 گروه گیاهپزشکی، دانشکدگان کشاورزی و منابع طبیعی دانشگاه تهران، کرج، ایران.
3 موسسه تحقیقات گیاهپزشکی، تهران، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
The cotton whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is one of the important pests of agricultural products that causes great economic losses. In this research, the effect of spirotetramat on three different developmental stages of the pest was studied in several populations that were collected from different provinces of Iran. Bioassay was done by leaf disk method. The results showed a higher sensitivity of the 2nd nymph stage compared to the adult stage and the egg stage; while the adult stage showed the least sensitivity to spirotetramat. The highest rate of resistance in different developmental stages was observed in the Jiroft population The LC50 ratios of adults in Karaj, Yazd, Pishwa, and Jiroft populations to sensitive one (Marand) were 7.6, 6.2, 4.2, and 9.6, respectively. For second instar nymphs, the ratios were 2.0, 2.2, 2.1, and 5.5 respectively. The investigation on detoxification enzymes indicated the higher activity of monooxygenase enzyme in the resistant population of Jiroft (3.34-fold) compared to the Marand population, which indicates the effective role of these enzymes in creating resistance. According to the results, to prevent resistance development, it is necessary to use other chemical compounds with different modes of action to prevent the occurrence of cross-resistance while affecting different developmental stages of pests.
کلیدواژهها [English]
Extended Abstract
Introduction
Cotton whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is one of the important pests of agricultural plants that causes great economic loss. The main damages occur by sucking plant sap and transmission of the viral disease which causes severe economic losses to the hosts. Chemical compounds play an important role in controlling the pest. However, it showed high degrees of resistance to different groups of insecticides. Monitoring of the pest resistance to various insecticide compounds is necessary for the application of IPM. In this research, the effect of insecticide spirotetramat, on resistance development of cotton whitefly was studied in samples of populations collected from various provinces of Iran.
Materials and Methods
Adult whitefly samples were collected from five different provinces on different host plants during 2020 and 2021. The plant leaves contain nymphs and adult insects were gathered and placed into cages under controlled conditions. The nymphs and adults were reared on eggplants and then used for bioassay and detoxifying enzyme activity tests at different developmental stages. Data analysis was done using Polo Plus software. Statistical analysis was done using SPSS version 23 software.
Results and Discussion
The results of bioassays showed a higher sensitivity of cotton whitefly at the second nymphal stage. The adult insect stage showed the least sensitivity. The highest rate of resistance in different developmental stages was observed in the Jiroft population. The LC50 ratio for spirotetramat in the populations collected from Karaj, Yazd, Pishva, and Jiroft was 7.6, 6.2, 4.2, and 9.6, in the adult stage and 2, 2.2, 1.2, and 5.5 for 2nd nymphs respectively, compared to the sensitive population (Marand). The investigation on detoxifying enzymes indicated the higher activity of mono-oxygenase enzymes (3.43 fold) in the population of Jiroft compared to the sensitive one.
Conclusion
In this study, we observed a low level of resistance for cotton whiteflies to spirotetramat at different growth stages of various pest populations. We also showed the effective role of mono-oxygenase enzymes in occurring resistance to this insecticide. To prevent the development of resistance, it is necessary to use chemical compounds with different modes of action such as spirotetramat in a rotational program of insecticide use. This approach should prevent the development of resistance of pests at different growth stages.