Activation of the ROS/CncC and 20-Hydroxyecdysone Signaling Pathways Is Associated with Xanthotoxin-Induced Tolerance to λ-Cyhalothrin in .

Adaptation to phytochemicals in herbivorous insects can influence tolerance to insecticides. However, it is unclear how insects use phytochemicals as cues to activate their metabolic detoxification systems. In this study, we found that dietary exposure to xanthotoxin enhanced tolerance of larvae to λ-cyhalothrin.

Phytochemical Flavone Confers Broad-Spectrum Tolerance to Insecticides in by Activating ROS/CncC-Mediated Xenobiotic Detoxification Pathways.

Tolerance to chemical insecticides can be driven by the necessity of herbivorous insects to defend against host plant-produced phytochemicals. However, how the phytochemicals are sensed and further transduced into a defense response associated with insecticide tolerance is poorly understood. Herein, we show that pre-exposure to flavone, a flavonoid phytochemical, effectively enhanced larval tolerance to multiple synthetic insecticides and elevated detoxification enzyme activities in .

Activation of the NR2E nuclear receptor HR83 leads to metabolic detoxification-mediated chlorpyrifos resistance in Nilaparvata lugens.

Increased production of detoxification enzymes appears to be the primary route for insecticide resistance in many crop pests. However, the mechanisms employed by resistant insects for overexpression of detoxification genes involved in insecticide resistance remain obscure. We report here that the NR2E nuclear receptor HR83 plays a critical role in chlorpyrifos resistance by regulating the expression of detoxification genes in the brown planthopper (BPH), Nilaparvata lugens.

Inhibition of hepatocyte nuclear factor 4 confers imidacloprid resistance in Nilaparvata lugens via the activation of cytochrome P450 and UDP-glycosyltransferase genes.

Increasing evidence indicates that insect resistance to synthesized insecticides is regulated by the nuclear receptors. However, the underlying mechanisms of this regulation are not clear. Here, we demonstrate that inhibition of hepatocyte nuclear factor 4 (HNF4) confers imidacloprid resistance in the brown planthopper (BPH) Nilaparvata lugens by regulating cytochrome P450 and UDP-glycosyltransferase (UGT) genes.

The KNRL nuclear receptor controls hydrolase-mediated vitellin breakdown during embryogenesis in the brown planthopper, Nilaparvata lugens.

Vitellin (Vn) homeostasis is central to the fecundity of oviparous insects. Most studies have focused on the synthesis and transportation of Vn as a building block for developing eggs during vitellogenesis; however, less is known about how the utilization of this nutrient reserve affects embryonic development. Here, we show that the single ortholog of the knirps and knirps-like nuclear receptors, KNRL, negatively regulates Vn breakdown by suppressing the expression of hydrolase genes in the brown planthopper, Nilaparvata lugens.

Effect of hepatocyte nuclear factor 4 on the fecundity of Nilaparvata lugens: Insights from RNA interference combined with transcriptomic analysis.

Hepatocyte nuclear factor 4 (HNF4) plays essential roles in regulating lipid metabolism and glucose homeostasis in female insects. However, little is known about the role of HNF4 in insect fecundity. Here we demonstrate that HNF4 regulates female fecundity by affecting egg hatching in the brown planthopper (BPH) Nilaparvata lugens.

Adipokinetic hormone regulates cytochrome P450-mediated imidacloprid resistance in the brown planthopper, Nilaparvata lugens.

Insect resistance to chemical insecticide is a global problem that presents an ongoing threat to sustainable agriculture. Although the increased production of detoxification enzymes has been frequently implicated in resistance development, the mechanisms employed by insecticide-resistant insects for overexpression of these genes remain elusive. Here we report that neuropeptide adipokinetic hormone (AKH) negatively regulates the expression of CYP6ER1 and CYP6AY1, two important cytochrome P450 monooxygenases (P450s) that confer resistance to neonicotinoid imidacloprid in the brown planthopper (BPH).

Activation of CncC pathway by ROS burst regulates cytochrome P450 CYP6AB12 responsible for λ-cyhalothrin tolerance in Spodoptera litura.

Frequent insecticide use poses an environmental hazard and also selects for insecticide tolerance. Increased metabolic detoxification by cytochrome P450 monooxygenases (P450s) is the most common mechanism of insecticide tolerance. However, the underlying regulatory mechanisms remain unknown.

Copper-induced HO accumulation confers larval tolerance to xanthotoxin by modulating CYP6B50 expression in Spodoptera litura.

In the plant-insect arms race, plants synthesize toxic compounds to defend against herbivorous insects, whereas insects employ cytochrome P450 monooxygenases (P450s) to detoxify these phytotoxins. As ubiquitous environmental contaminants, heavy metals can be easily absorbed by plants and further accumulated in herbivorous insects through the food chains, resulting in tangible consequences for plant-insect interactions. However, whether heavy metals can influence P450 activities and thereby cause further effects on larval tolerance to phytotoxins remains unknown.

Adipokinetic Hormone Receptor Mediates Trehalose Homeostasis to Promote Vitellogenin Uptake by Oocytes in .

Adipokinetic hormones (AKHs) are well known to mobilize lipids and carbohydrates for energy-consuming activities in insects. These neuropeptides exert their functions by interacting with AKH receptors (AKHRs) located on the plasma membrane of fat body cells, which regulates energy mobilization by stimulating lipolysis of triacylglycerols (TAG) to diacylglycerols (DAG) and conversion of glycogen into trehalose. Here, we investigated the roles of AKH/AKHR signaling system in trehalose metabolism and vitellogenesis during female reproduction in the brown planthopper, .

Adipokinetic Hormone Receptor Mediates Lipid Mobilization to Regulate Starvation Resistance in the Brown Planthopper, .

Lipid storage must be efficiently mobilized to sustain the energy demands during processes of exercise or starvation. In insects, adipokinetic hormone (AKH) and brummer lipase are well-known regulators of lipid mobilization. We recently demonstrated that brummer-dependent lipolysis regulates starvation resistance in the brown planthopper, , one of the most destructive rice pests.

Deficiency of Brummer Impaires Lipid Mobilization and JH-Mediated Vitellogenesis in the Brown Planthopper, .

Provisioning of sufficient lipids and vitellogenin to the oocytes is an indispensable process for fecundity of oviparous insects. Acute mobilization of lipid reserves in insects is controlled by the Brummer (Bmm), an orthologous of human adipose triglyceride lipase (ATGL). To investigate the functional roles of brummer-mediated lipolysis in the fecundity of the brown planthopper, , RNA interference (RNAi) analyses were performed with double-stranded RNA (dsRNA) against in adult females.