Praveen Joshi S S, Sumathi Ettiappan, Murugan Marimuthu, Haran Ramkumar, Priya Sundaravadivel Sathiya, Shandeep Ganeshan, Mohankumar Subbarayalu, Uma Doraiswamy, Nelson Ashitha
Department of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, 641003, India.
Department of Nematology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, 641003, India.
Exp Appl Acarol. 2024 Dec 30;94(1):22. doi: 10.1007/s10493-024-00991-8.
Two-spotted spider mite (TSSM), Tetranychus urticae Koch is a devastating polyphagous mite causing considerable economic loss. Acaricides are showered in crops to manage this pest. The pest is known for developing resistance to several classical acaricides. The study was aimed at the exploration of botanical acaricide for the management of TSSM, T. urticae. Adulticidal action of ethyl acetate, ethanol and water extracts of leaves of Sesbania grandiflora (Fabaceae) were tested on T. urticae. The results showed that ethyl acetate extract showed the maximum mite mortality of 94.44 per cent, followed by ethanol extract at 87.78 per cent at 5 per cent concentration. LC of ethyl acetate and ethanol extracts were 1.00 and 4.19 per cent, respectively. The aqueous extract gave 94.44 per cent mortality at a very high concentration of 15% with LC of 8.57%. Molecules from the GC-MS analysis of S. grandiflora ethyl acetate leaf extract were subjected to molecular docking using acetylcholine esterase as the target molecule. The major phytomolecules identified in the ethyl acetate leaf extract of S. grandiflora were stigmasterol (15.45%), phytol (13.60%), beta-amyrone (8.72%), and squalene (7.51%). Squalene, a biomolecule with the lowest binding energy was selected from the docking result. The toxicity of squalene was evident from the fact that it caused 81.11, 85.55 and 87.78 per cent mortality at 1800, 2000 and 2200 ppm, respectively at 48 h after treatment. After, 72 h, 100 per cent mortality was recorded at 1800 ppm. This study reveals that squalene can be formulated and used as the best alternative to tackle T. urticae.
二斑叶螨（TSSM），即二斑叶螨（Tetranychus urticae Koch），是一种极具破坏力的多食性螨类，会造成相当大的经济损失。人们在作物上大量喷洒杀螨剂来防治这种害虫。这种害虫因对几种传统杀螨剂产生抗性而闻名。该研究旨在探索用于防治二斑叶螨的植物源杀螨剂。对大花田菁（豆科）叶片的乙酸乙酯、乙醇和水提取物对二斑叶螨的成虫致死作用进行了测试。结果表明，乙酸乙酯提取物在5%浓度下对螨的致死率最高，为94.44%，其次是乙醇提取物，致死率为87.78%。乙酸乙酯和乙醇提取物的致死浓度分别为1.00%和4.19%。水提取物在15%的高浓度下致死率为94.44%，致死浓度为8.57%。以乙酰胆碱酯酶为靶分子，对大花田菁乙酸乙酯叶提取物的气相色谱 - 质谱分析得到的分子进行分子对接。在大花田菁乙酸乙酯叶提取物中鉴定出的主要植物分子有豆甾醇（15.45%）、叶绿醇（13.60%）、β - 香树精（8.72%）和角鲨烯（7.51%）。从对接结果中选择了结合能最低的生物分子角鲨烯。角鲨烯的毒性从以下事实可见一斑：处理后48小时，在1800、2000和2200 ppm浓度下，其致死率分别为81.11%、85.55%和87.78%。72小时后，在1800 ppm浓度下记录到100%的致死率。这项研究表明，角鲨烯可以被配制并用作防治二斑叶螨的最佳替代品。
