Dept of Biochemistry, Univ of Nigeria, Nsukka, Enugu, Nigeria.
Dept of Biochemistry, Bayero Univ, Kano, Nigeria.
Neotrop Entomol. 2021 Jun;50(3):484-496. doi: 10.1007/s13744-021-00858-2. Epub 2021 Mar 4.
Insecticide resistance in mosquitoes is increasing amidst growing cases of global malaria, leading to high fatality in mostly Africa. To overcome the resistance as well as environmental effects of the synthetic insecticides, preliminary insecticidal and botanical potentiating effects of sub-lethal concentration (LC) Ficus sycomorus active fraction (AFFS) and its synergistic potential with standard insecticide permethrin were evaluated against malarial vector Anopheles coluzzii (Coetzee & Wilkerson) populations. The glutathione-S-transferase (GST) inhibitory activity of the AFFS was also investigated compared to standard GST inhibitor, diethyl meleate (DEM). The WHO standard protocol for adult bioassay was used to expose the adult mosquitoes with sub-lethal concentration (LD=0.49 mg/ml) of the plants' active fraction and permethrin (0.75%). The permethrin susceptibility screening result showed high level of resistance to permethrin in the field populations of A. coluzzii from Kano with 50.29 ± 2.14% average mortality after exposure to WHO diagnostic dose 0.75% permethrin. Post hoc Fisher's exact test showed that combination of sub-lethal concentration of AFFS with permethrin (mortality=73.02±12.10%; p=0.00352; RR=0.6923 and 95% CI = 0.5358-0.8946) was statistically significant, while the combination of sub-lethal concentration of AFFS with DEM showed no statistical difference (mortality=63.22±5.03; p=1; RR=0.6667 and 95% CI=0.4470-0.8438). This potentiation effect was signified to be additive effects with co-toxicity factor (CTF) of - 12.66. There was significant reduction of GST activities in the AFFS- and permethrin -exposed groups compared to unexposed populations of A. coluzzii (p < 0.05). The AFFS additively potentiate the permethrin activities by inhibiting GSTs, bio-transformational enzymes implicated in pyrethroids resistance. This study finding generally signifies the potential for bio-rational insecticide approach for malarial vector control.
在全球疟疾病例不断增加的情况下，蚊子的抗药性也在不断增强，这导致大多数非洲地区的死亡率居高不下。为了克服合成杀虫剂的抗药性和环境影响，评估了亚致死浓度（LC）榕属植物活性部分（AFFS）的初步杀虫和植物增效作用及其与标准杀虫剂氯菊酯的协同潜力，以对抗疟疾病媒按蚊属。还研究了 AFFS 的谷胱甘肽-S-转移酶（GST）抑制活性，并与标准 GST 抑制剂二乙基马来酸酯（DEM）进行了比较。使用世界卫生组织成人生物测定标准方案，使成蚊接触亚致死浓度（LD=0.49 mg/ml）的植物活性部分和氯菊酯（0.75%）。氯菊酯敏感性筛选结果显示，来自卡诺的按蚊属野外种群对氯菊酯具有高水平的抗药性，接触世界卫生组织诊断剂量 0.75%氯菊酯后，平均死亡率为 50.29±2.14%。事后 Fisher 精确检验表明，亚致死浓度的 AFFS 与氯菊酯（死亡率=73.02±12.10%；p=0.00352；RR=0.6923，95%CI=0.5358-0.8946）联合使用具有统计学意义，而亚致死浓度的 AFFS 与 DEM 联合使用则没有统计学差异（死亡率=63.22±5.03；p=1；RR=0.6667，95%CI=0.4470-0.8438）。这种增效作用被证明是具有协同毒性因子（CTF）-12.66 的相加作用。与未接触氯菊酯的按蚊属种群相比，AFFS 和氯菊酯暴露组的 GST 活性显著降低（p<0.05）。AFFS 通过抑制 GSTs 来增强氯菊酯的活性，GSTs 是与拟除虫菊酯抗性有关的生物转化酶。这项研究结果普遍表明，采用基于生物合理性的杀虫剂方法来控制疟疾媒介具有潜力。
