Enzymology, Histological and Ultrastructural Effects of Ar-Turmerone on Culex pipiens pallens Larvae

Abstract

Our previous article demonstrated that ar-turmerone ((6S)-2-methyl-6-(4-methylphenyl)-2-hepten-4-one) extracted from Curcuma longa L. has a significant larvicidal activity against the fourth instar larvae of Culex pipiens pallens. To reveal the effects of ar-turmerone on C. pipiens pallens larvae, light microscopy and transmission electron microscopy were used to observe the histological and ultrastructure changes in muscle and digestive tissues of fourth instar larvae. It was also revealed by detecting the activity of the acetylcholinesterase (AChE) enzyme and three detoxifying enzymes, including carboxylesterase (CarE), glutathione-S-transferase (GST) and Cytochrome P450 monooxidases (P450). The observation under the light microscope showed that the larvae displayed a disruption of myofibril in ventral muscle cells, the disappearance of nucleolus in the malpighian tubule cells, and the exfoliation of the brush border in midgut epithelial cells, 24 h after treatment. The observation under the transmission electron microscope displayed disorganized Z-lines in the ventral muscle cells, and dissolved membrane of mitochondria, nuclear and endoplasmic reticulum in abdominal cells. The enzymatic activity results showed that ar-turmerone significantly increased the level of detoxifying enzymes, while the activity of AChE was not obviously affected. All the results suggest that the larvicidal mechanism of ar-turmerone is estimated to be stomach poison and the active sites might be the muscle and digestive tissues, and the mode of action of ar-turmerone may be unrelated to AChE.

Another Mode of Action of Temephos Against Aedes aegypti Larvae: A Stomach Poison Investigation

“…39 The epithelial cells protruded in the midgut of Culex pipiens larvae, with the brush border entirely disorganized and thinning down after 24 h exposure with ar-turmerone (200 ppm). 45 Fiaz et al discovered, similarly to this work, that a damaged epithelial layer was associated with cell debris discharged in the midgut lumen, cytoplasm vacuolization followed by cell breakdown, and cell debris release into the midgut lumen. 46 The peritrophic membrane, also known as the peritrophic matrix (PM), is a non-cellular substance, a semi-permeable and fibrous layer created by midgut epithelial cell secretion, that separates the ingested food from the midgut epithelium.…”

Chemical screening, insecticidal and reprotoxic activities of Tecoma stans ethanolic leaf extract against the vector mosquito Culex pipiens

“…caspius treated with Mentha rotundifolia (Kharoubi et al, 2020). Moreover, Liu et al (2020) showed that ar‐turmerone significantly increased the level of GST enzyme in Culex pipiens pallens larvae. It was shown, also, an induction of this detoxifying enzyme activity in Spodoptera litura after application of purified compounds of Alpinia galangal (Datta et al, 2020).…”

Assessment of susceptible Culex quinquefasciatus larvae in Indonesia to different insecticides through metabolic enzymes and the histopathological midgut

“…Detoxifying enzymes consisting of acetylcholinesterase (AChE), glutathione S transferase (GST), esterase, and cytochrome c oxidase (oxidase) have been applied to assess the susceptibility of mosquito species to different insecticides. They could also be applied to assess the susceptibility of mosquito larvae to insecticides ( Boyer et al., 2006 ; Liu et al., 2020 ). Thus, metabolic enzymes are an important tool to assess the susceptibility of mosquito larvae and adults to insecticides.…”