Insecticidal Potential of α-Pinene and β-Caryophyllene against Myzus persicae and Their Impacts on Gene Expression

Abstract

<i>Myzus persicae</i> (<i>M. persicae</i>) is now considered a threat to agricultural crops due to economic losses. Numerous synthetic insecticides applied every year against <i>M. persicae</i>, are reported to be unsafe for environment, humans, and beneficial insects. Furthermore, several species of <i>Myzus</i> have been found to develop resistance due to over application of these insecticides. Therefore, it is required to find some novel insecticide that would be safe for the environment as well as for humans. In the current study, two major pure constituents α-pinene and β-caryophyllene were evaluated for their insecticidal potential against <i>M. persicae</i> using a fumigant toxicity assay. Furthermore, impact of α-pinene and β-caryophyllene on expression of five different genes, e.g., HSP 60, FPPS I, OSD, TOL and ANT responsible for reproduction, dispersion, and growth of <i>M. persicae</i> has also been investigated. To perform fumigant toxicity assay, five different concentrations (3.5, 4, 4.5, 5 and 6 μL L⁻¹) of α-pinene and β-caryophyllene were prepared. Lethal concentration (LC) was calculated, and gene expression studies were executed through qRT PCR at LC₃₀ of α-pinene and β-caryophyllene. Both constituents demonstrated excellent fumigant toxicity effects against <i>M. persicae</i> at all five concentrations. However, α-pinene shows significantly better results (98%) as compared to β-caryophyllene (80%) after 72 h at 6 μL L⁻¹ of dose. The highest upregulation in expression was demonstrated at LC₃₀ dose of α-pinene in five in three out of five genes understudy (TOL, ANT, and FPPS I). Conversely, two genes HSP 60 and OSD demonstrated downregulation at LC₃₀ dose of β-caryophyllene. Conclusively, our results highlighted the promising insecticidal potential of both compounds α-pinene and β-caryophylleneby interfering with the reproduction and development related processes in <i>M. persicae</i>, allowing us to recommend the phytoconstituents under investigation as an ecofriendly alternative to synthetic insecticides.