AlJabr Ahmed Mohammed, Hussain Abid, Rizwan-Ul-Haq Muhammad, Al-Ayedh Hassan
Laboratory of Bio-Control and Molecular Biology, Department of Arid Land Agriculture, College of Agricultural and Food Sciences, King Faisal University, Hofuf 31982, Al-Ahsa, Saudi Arabia.
Life Science and Environment Research Institute, King Abdulaziz City for Science and Technology, P.O. Box 6086, Riyadh 11442, Saudi Arabia.
Molecules. 2017 Jan 20;22(1):169. doi: 10.3390/molecules22010169.
This study aimed to explore the larvicidal and growth-inhibiting activities, and underlying detoxification mechanism of red palm weevil against phenylpropanoids, an important class of plant secondary metabolites. Toxicity of α-asarone, eugenol, isoeugenol, methyl eugenol, methyl isoeugenol, coumarin, coumarin 6, coniferyl aldehyde, diniconazole, ethyl cinnamate, and rosmarinic acid was evaluated by incorporation into the artificial diet. All of the phenylpropanoids exhibited dose- and time-dependent insecticidal activity. Among all the tested phenylpropanoids, coumarin exhibited the highest toxicity by revealing the least LD value (0.672 g/L). In addition, the most toxic compound (coumarin) observed in the current study, deteriorated the growth resulting tremendous reduction (78.39%) in efficacy of conversion of digested food (ECD), and (ECI) efficacy of conversion of ingested food (70.04%) of tenth-instar red palm weevil larvae. The energy-deficient red palm weevil larvae through their intrinsic abilities showed enhanced response to their digestibility resulting 27.78% increase in approximate digestibility (AD) compared to control larvae. The detoxification response of larvae determined by the quantitative expression of , , and revealed enhanced expression among moderately toxic and ineffective compounds. These genes especially and detoxify the target compounds by enhancing their solubility that leads rapid excretion and degradation resulting low toxicity towards red palm weevil larvae. On the other hand, the most toxic (coumarin) silenced the genes involved in the red palm weevil detoxification mechanism. Based on the toxicity, growth retarding, and masking detoxification activities, coumarin could be a useful future natural red palm weevil-controlling agent.
本研究旨在探讨红棕象甲对苯丙烷类化合物（一类重要的植物次生代谢产物）的杀幼虫和生长抑制活性及其潜在的解毒机制。通过将α-细辛脑、丁香酚、异丁香酚、甲基丁香酚、甲基异丁香酚、香豆素、香豆素6、松柏醛、烯唑醇、肉桂酸乙酯和迷迭香酸掺入人工饲料中来评估其毒性。所有苯丙烷类化合物均表现出剂量和时间依赖性的杀虫活性。在所有测试的苯丙烷类化合物中，香豆素的毒性最高，其最低致死剂量值（LD）为0.672 g/L。此外，本研究中观察到的毒性最强的化合物（香豆素）会抑制生长，导致十龄红棕象甲幼虫的消化食物转化率（ECD）大幅降低（78.39%），摄入食物转化率（ECI）降低（70.04%）。能量不足的红棕象甲幼虫凭借其自身能力，对消化率表现出更强的反应，与对照幼虫相比，近似消化率（AD）提高了27.78%。通过对 、 和 的定量表达确定的幼虫解毒反应表明，在中等毒性和无效化合物中这些基因的表达增强。这些基因，尤其是 和 ，通过提高目标化合物的溶解度来解毒，从而导致其快速排泄和降解，对红棕象甲幼虫的毒性较低。另一方面，毒性最强的（香豆素）使参与红棕象甲解毒机制的基因沉默。基于毒性、生长抑制和掩盖解毒活性，香豆素可能是未来一种有用的天然红棕象甲控制剂。
