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Aldehyde oxidases (AOXs) are a group of metabolic enzymes that play critical roles in the degradation of xenobiotics and chemicals. However, the physiological function of this enzyme in insects remains poorly understood. In this study, three TcAOX genes (TcAOX1 , TcAOX2 , TcAOX3) were identified and characterized from Tribolium castaneum genome. Spatiotemporal expression profiling showed that TcAOX1 expression was most highly expressed at the early pupal stage and was predominantly expressed in the antennae of adults, indicating that TcAOX1 was involved in the degradation of chemical signals; TcAOX2 expression was most highly expressed at the late pupal stage and was mainly expressed in the fat body, epidermis of larvae and adults, respectively; and TcAOX3 expression was in all stages and was primarily expressed in the head of adults. Moreover, the transcripts of TcAOX2 and TcAOX3 were significantly induced after exposure to plant oil, and RNA interference (RNAi) targeting of each of them enhanced the susceptibility of beetles to this plant toxicant, suggesting that these two genes are associated with plant toxicant detoxification. Intriguingly, knockdown of the TcAOX1 led to reductions in female egg-laying but unchanged the hatchability and the development of genital organs, suggesting that this gene may mediate fecundity by effecting the inactivation of chemical signals in T. castaneum. Overall, these results shed new light on the function of AOX genes in insects, and could facilitate the development of research on pest control management. [ABSTRACT FROM AUTHOR]

Background: Insect cytochrome P450 monooxygenases (P450s) play a crucial role in phytochemical metabolism and tolerance. Three P450 genes (TcCYP4Q3, TcCYP4Q5, and TcCYP4Q7) are associated with the response of eugenol in Tribolium castaneum. However, the responding mechanisms of these P450 genes to eugenol remain unknown. Results: Here, spatiotemporal expression profiling revealed that TcCYP4Q3 and TcCYP4Q5 were most highly expressed in late adult, while TcCYP4Q7 was predominantly expressed in late larva; and all of these three P450 genes were mainly expressed in the fat body of larvae. Furthermore, the expressions of these three P450 genes were significantly up‐regulated after exposure to eugenol, and depletion of them enhanced the susceptibility of beetles to eugenol. Interestingly, RNA interference (RNAi) against the CncC gene, a transcription factor of CncC signaling pathway associated with regulation of insect P450s in response to phytochemicals, reduced the transcripts of these three P450 genes following exposure to eugenol. Investigation of CncC signaling pathway showed that this pathway could be activated by eugenol. Conclusion: Altogether, the results indicate that these three P450 genes are regulated by CncC signaling pathway to participate in the susceptibility of Tribolium castaneum to phytochemicals. These findings will aid implications for the development of novel therapeutics to control pest. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Uridine diphosphate glucosyltransferases (UGTs), which are phase II detoxification enzymes, are found in various organisms. These enzymes play an important role in the detoxification mechanisms of plant allelopathy and in insects. Artemisia vulgaris L. (Asterales: Asteraceae: Artemisia) essential oil has strong contact toxicity to Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) larvae. However, the effect of A. vulgaris essential oil on UGTs is unclear. In this study, A. vulgaris essential oil was shown to significantly induce the expression of the TcUgt86Dg transcript. Furthermore, treatment of TcUgt86Dg -silenced individuals with A. vulgaris essential oil resulted in higher mortality than for the control individuals, indicating that TcUgt86Dg is involved in detoxification of A. vulgaris essential oil in T. castaneum. The developmental expression profile showed that the expression of TcUgt86Dg in late adults was higher than in other developmental stages. Furthermore, the expression profile in adult tissues revealed higher expression of TcUgt86Dg in the head, antenna, fat body, and accessory gland than in other tissues. These data show that TcUgt86Dg may be involved in the metabolism of exogenous toxins by T. castaneum ; thus, our results have elucidated one possible mechanism of resistance to A. vulgaris essential oil and provide a theoretical basis for a control scheme for T. castaneum. [ABSTRACT FROM AUTHOR]

Tribolium castaneum (T. castaneum) is a worldwide pest of stored grain that mainly harms flour, and not only causes serious loss of flour quality but also leads to deterioration of flour quality. Chemical detection plays a key role in insect behavior, and the role of odorant-binding proteins (OBPs) in insect chemical detection has been widely studied. However, the mechanism of OBPs in insect defense against exogenous toxic substances is still unclear. In this study, biochemical analysis showed that eugenol, the active component of A. vulgaris essential oil, significantly induced the expression of the OBP gene OBPC12 from T. castaneum (TcOBPC12). The mortality of late larvae treated with eugenol was higher than that of the control group after RNA interference (RNAi) against TcOBPC12 , which indicates that the OBP gene is involved in the eugenol defense mechanism and leads to a decrease in sensitivity to eugenol. Tissue expression profiling showed that the expression of TcOBPC12 in the epidermis, hemolymph, and intestine was higher than in other larval tissues, and TcOBPC12 was expressed mainly in the epidermis, head, and fat body of adults. The developmental expression profile showed that the expression of TcOBPC12 in late eggs, early and late larval stages, and late adult stages was higher than in other developmental stages. These data suggest that TcOBPC12 may be involved in the absorption of exogenous toxic substances by the larvae from T. castaneum. Our results provide a theoretical basis for the metabolism and degradation mechanism of exogenous toxic substances and help explore more potential target genes of insect pests. [Display omitted] • The expression of TcOBPC12 was up-regulated at 60 and 72 h after eugenol treatment. • TcOBPC12 was highly expressed in late eggs, early and late larval, and late adult stages. • TcOBPC12 was abundant in the epidermis, hemolymph and intestine of the late larval. • TcOBPC12 was more in the epidermis, head and fat body of the early adult. • RNAi of TcOBPC12 increased the mortality of late larvae after eugenol treatment. [ABSTRACT FROM AUTHOR]

Tribolium castaneum is an agricultural and stored pest found throughout the world. The cytochrome P450 genes of T. castaneum can encode various detoxification enzymes and catabolize heterologous substances, conferring tolerance to insecticides. Herein, we describe the identification of a P450 gene (CYP9Z6) from T. castaneum and investigated its expression profile and potential role in the detoxification of terpinen-4-ol. TcCYP9Z6 expression was significantly induced after exposure to terpinen-4-ol, and RNA-mediated silencing of TcCYP9Z6 increased terpinen-4-ol-induced larval mortality from 47.75% to 63.92%, showing that TcCYP9Z6 is closely related to the detoxification of terpinen-4-ol. The developmental expression profile revealed that TcCYP9Z6 was mainly expressed in late adults and late larvae. Tissue expression profiling revealed that the highest TcCYP9Z6 expression occurred in the head, in both the adult and the larval tissues, followed by the gut in larvae and the antennae in adults. These developmental stages and tissues with high TcCYP9Z6 expression are closely related to the detoxification of heterologous substances. These results indicated that TcCYP9Z6 may play a pivotal role in the detoxification of terpinen-4-ol, which provides support for using TcCYP9Z6 a potential gene for the RNAi-mediated prevention and control of T. castaneum. [Display omitted] • Expression of TcCYP9Z6 gene was induced with terpinen-4-ol. • Knockdown of TcCYP9Z6 increases sensitivity of T. castaneum to terpinen-4-ol. • The CYP9Z6 of T. castaneum is related to its detoxification. [ABSTRACT FROM AUTHOR]