Determination of the expression level of some genes in the insecticide resistance mechanism of potato beetle(leptinotarsa decemlineata (say) coleoptera: Chrysomelidae)

In this study, the activity of three different essential oil compounds on potato beetle was investigated. In addition, the insecticidal activity of the high activity timol compound on different stages of potato beetle was investigated. In addition, time-dependent gene expression analysis of three different detoxification enzymes was performed. While alpha-terpinene and beta-pinene showed very low activity on third stage potato beetle larvae, timol activity was found to be high. Timol caused 100% mortality on third instar larvae at 7.5% application dose. The effect of the compound on the fourth stage larvae was determined as 68.47% at 12.5% dose, while this rate was determined as 70.34% in adult individuals at the end of 72 hours at 20% application dose. In the gene expression studies, GlutathioneS-transferase (GST) expression increased significantly in a time- dependent manner. At 4 hours after treatment, GST mRNA levels were 1.5-fold higher than in the control group. The expression rate reached its highest level at 12 hours with a 2.7-fold increase. Cytochrome P450 monooxygenase (CYP450) expression showed a delayed but consistent induction pattern, reaching up to 1.91-fold after 24 hours. Carboxylesterase (CarE) expression remained relatively unchanged throughout the 24 h monitoring period.