Contact and fumigant toxicities of monoterpenes and phenylpropenes, and their possible mode of action to oleander aphid

• Published in: International journal of tropical insect science 2022-06, Vol.42 (3), p.2195-2201
• Main Authors: Hussein, Hanna S., El-Deeb, Dalia A., Tawfeek, Mohamed E., Abdelgaleil, Samir A. M.
• Format: Article
• Language: English
• Subjects: Acetylcholinesterase; Adenosine; Biomedical and Life Sciences; Camphor; Cineole; Cinnamaldehyde; Citronellal; Contact; Entomology; Eugenol; Fumigation; Life Sciences; Menthol; Mode of action; Monoterpenes; Nerium; Original Research Article; p-Cymene; Toxicants; Toxicity; α-Pinene
• ISSN: 1742-7592; 1742-7584; 1742-7592
• DOI: 10.1007/s42690-022-00740-7

In the present study, ten monoterpenes and phenylpropenes were tested for their contact and fumigant toxicities against oleander aphid,  Aphis nerii (Hemiptera: Aphididae). Also, the inhibitory effect of compounds on acetylcholinesterase (AChE) and adenosine triphosphatases (ATPases) activities was assessed in vitro to explore their possible modes of action. (-)-Menthol and (+)-camphor were the most potent contact toxicants among the tested compounds against A. nerii third nymphal instar with LC 50 values of 0.06 and 0.08 mg/L, respectively. In contrary, 1,8-cineole, p -cymene and α -pinene showed a weak or no contact toxicity where their LC 50 values were >10 mg/L. In fumigation assay, cuminaldehyde (LC 50 = 3.10 µl/L), (+)-camphor (LC 50 = 3.57 µl/L) and (-)-menthol (LC 50 = 3.59 µl/L) showed the highest toxicity against A. nerii , while eugenol (LC 50 >50 µl/L) was the less effective compound. (−)-Citronellal (IC 50 = 2.22 mM) and trans -cinnamaldehyde (IC 50 = 1.12 mM) caused the highest inhibitory effect on AChE and ATPases activity, respectively. In general, all compounds showed strong inhibitory effect on the activity of ATPases than AChE.