جستجوی مقالات مرتبط با کلیدواژه "resistance mechanisms" در نشریات گروه "گیاهپزشکی"

The two-spotted spider mite, Tetranychus urticae</em>, is a major pest of crops and ornamental plants worldwide. It is a highly polyphagous pest that has a notorious reputation for its ability to rapidly develop resistance to commonly used pesticides. Thus, in the current study, the contact toxicity of propargite (EC 57%) and chlorpyrifos (EC 40.8%) was investigated against two populations of T. urticae</em> from Iran, Mahallat (MhR) and Karaj (KrS), using a leaf-dip bioassay. Findings showed that the LC50</sub> of propargite against MhR and KrS populations was 5337.90 and 116.81 mg a.i/l, respectively. While the LC50</sub> of the chlorpyrifos against MhR and KrS populations was 2760.83 and 479.25 mg a.i/l, respectively. Based on the median lethal concentrations (LC50</sub>), MhR and KrS populations were considered as resistant and susceptible populations to both pesticides, respectively. MhR population was 5.76-fold and 45.70-fold more resistant to chlorpyrifos and propargite than the KrS population, respectively. Insecticide synergists including triphenyl phosphate (TPP), piperonyl butoxide (PBO), and diethyl maleate (DEM)) revealed the contribution of esterases, glutathione S-transferases (GST), and cytochrome P450 </sub>monooxygenases (P450</sub>s) to resistance. Nonetheless, the involvement of esterases and P450</sub>s was more evident against chlorpyrifos and propargite, respectively. The activity of P450</sub>s, GSTs, esterases, and acetylcholinesterase (AChE) was measured in susceptible and resistant populations. All enzymes showed significantly higher activity in the resistant population than in the susceptible one. Additionally, zymogram analysis of esterase showed two distinct bands in the MhR population, whereas the stronger band was absent in KrS population. These results indicate that metabolic pathways are associated with chlorpyrifos and propargite resistance in the MhR population.

Two-spotted spider mite, Teranychus urticae (Acari: Tetranychide), is one of the most important agricultural pests throughout the world. The high reproductive potential, short life cycle, combined with frequent acaricide applications has resulted in resistance development to a wide range of acaricides. Resistance to acaricides has an important role in inefficiency of chemical control of this pest. In the present study, the susceptibility of two populations of two-spotted spider mite collected from Karaj (KrS) and Mahallat (MhR) to spirodiclofen was investigated.
The bioassay was conducted using a leaf-dip method on same-age protonymphs. Bioassay results showed that there was a significant difference between LC50 values of KrS and MhR populations. The resistance ratio was obtained as 22.19. The synergistic effects of triphenyl phosphate (TPP), piperonyl butoxide (PBO) and diethyl maleate (DEM) were assessed using residual contact vial (RCV) bioassay method. Results of the synergistic studies showed significant differences between LC50 values of spirodiclofen with spirodiclofen PBO and spirodiclofen TPP in MhR population. The most synergistic effect in MhR population was related to PBO. The results of enzyme assays revealed that the most ratio activity in MhR population to KrS population was related to cytochrome P450 monoxygenase (3.02) and the lowest ratio activity was related to glutathione S-transferase (GST) (1.40). These results confirmed that esterase and cytochrome P450 monoxygenase are probably involved in resistance of T. urticae to spirodiclofen.