Prasannakumar Nagalapura Ramakrishnappa, Jyothi Nagendraiah, Keerthi Manikyanahalli Chandrashekara, Rao Vala Keshava, Saroja Sarikonda, Samuel Duleep Kumar, Navyashree Shylapura Erakyathappa, Sridhar Vaddi, Lokesh Ankanahalli Naranayanashetty
Division of Crop Protection, ICAR-Indian Institute of Horticultural Research, Hessarghatta Lake, Bengaluru, India.
Division of Basic Sciences, ICAR-Indian Institute of Horticultural Research, Hessarghatta Lake, Bengaluru, India.
Neotrop Entomol. 2025 Apr 17;54(1):59. doi: 10.1007/s13744-025-01269-3.
Tetranychus urticae Koch (Acari: Tetranychidae), commonly known as the two-spotted spider mite, is a major polyphagous pest that affects a wide range of vegetable crops. Infestation of T. urticae is more prominent on eggplant which causes 50-80% yield loss if no control measures initiated. The economic threat posed by T. urticae is constantly increasing because of the development of pesticide resistance and resurgence. One of best alternative management strategies is use of plant-based pesticides like secondary metabolites and essential oils (EOs) which provides sustainable and long-term protection. In the present study, EO extracted from a billygoat weed, Ageratum conyzoides L. (Asterales: Asteraceae), and its binary compounds were evaluated against T. urticae. The A. conyzoides EOs showed highest mortality (97.5% with the LC 10.61 µL/mL), due to the presence of Precocene I (32.32%), Geraniol (1.23%), and Neral (0.55%). Among the binary compounds, Geraniol (95%) showed highest mortality having LC (95%) of 9.59 µL/mL followed by Citronellol (77.5%) and Alpha-pipene (75%). Significant increase in the activity of esterases, glutathione S-transferase, and acetylcholine esterases contributed for the toxicity in T. urticae following exposure to essential oils (EO) and their binary compounds. SEM images revealed shrinking of the bodies of treated T. urticae along with reduced body measurements compared to the untreated individuals. The present study indicates that A. conyzoides EO could be used for development of new acaricides for sustainable management of T. urticae.
二斑叶螨（Tetranychus urticae Koch，蜱螨亚纲：叶螨科），通常被称为二斑叶螨，是一种主要的多食性害虫，会影响多种蔬菜作物。二斑叶螨在茄子上的侵害更为突出，如果不采取控制措施，会导致50%-80%的产量损失。由于抗药性的发展和虫口回升，二斑叶螨造成的经济威胁在不断增加。最佳的替代管理策略之一是使用基于植物的农药，如次生代谢物和精油（EOs），它们能提供可持续的长期保护。在本研究中，对从胜红蓟（Ageratum conyzoides L.，菊目：菊科）中提取的精油及其二元化合物进行了针对二斑叶螨的评估。胜红蓟精油表现出最高的死亡率（在LC为10.61微升/毫升时死亡率为97.5%），这是由于其中含有早熟素I（32.32%）、香叶醇（1.23%）和橙花醛（0.55%）。在二元化合物中，香叶醇（95%）表现出最高的死亡率，其LC(95%)为9.59微升/毫升，其次是香茅醇（77.5%）和α-蒎烯（75%）。接触精油（EO）及其二元化合物后，酯酶、谷胱甘肽S-转移酶和乙酰胆碱酯酶的活性显著增加，这导致了二斑叶螨的毒性。扫描电子显微镜图像显示，与未处理的个体相比，经处理的二斑叶螨身体收缩，身体尺寸减小。本研究表明，胜红蓟精油可用于开发新型杀螨剂，以可持续地管理二斑叶螨。
