Cytochrome P450 monooxygenases (P450s) of insects play crucial roles in the metabolism of endogenous and dietary compounds. Tobacco cutworm moth (Spodoptera litura), an important agricultural pest, causes severe yield losses in many crops. In this study, we identified CYP9A40, a novel P450 gene of S. litura, and investigated its expression profile and potential role in detoxification of plant allelochemicals and insecticides. The cDNA contains an open reading frame encoding 529 amino acid residues. CYP9A40 transcripts were found to be accumulated during various development stages of S. litura and were highest in fifth and sixth instar larvae. CYP9A40 was mainly expressed in the midgut and fat body. Larval consumption of xenobiotics, namely plant allelochemicals (quercetin and cinnamic acid) and insecticides (deltamethrin and methoxyfenozide) induced accumulation of CYP9A40 transcripts in the midgut and fat body. Injection of dsCYP9A40 (silencing of CYP9A40 by RNA interference) significantly increased the susceptibility of S. litura larvae to the tested plant allelochemicals and insecticides. These results indicate that CYP9A40 expression in S. litura is related to consumption of xenobiotics and suggest that CYP9A40 is involved in detoxification of these compounds.

In insects, cytochrome P450 monooxygenases (P450s or CYPs) are known to be involved in the detoxification and metabolism of insecticides, leading to increased resistance in insect populations. Spodoptera exigua is a serious polyphagous insect pest worldwide and has developed resistance to various insecticides. In this study, a novel CYP3 clan P450 gene CYP9A105 was identified and characterized from S. exigua. The cDNAs of CYP9A105 encoded 530 amino acid proteins, respectively. Quantitative real-time PCR analyses showed that CYP9A105 was expressed at all developmental stages, with maximal expression observed in fifth instar stage larvae, and in dissected fifth instar larvae the highest transcript levels were found in midguts and fat bodies. The expression of CYP9A105 in midguts was upregulated by treatments with the insecticides α-cypermethrin, deltamethrin and fenvalerate at both LC₁₅ concentrations (0.10, 0.20 and 5.0 mg/L, respectively) and LC₅₀ concentrations (0.25, 0.40 and 10.00 mg/L, respectively). RNA interference (RNAi) mediated silencing of CYP9A105 led to increased mortalities of insecticide-treated 4th instar S. exigua larvae. Our results suggest that CYP9A105 might play an important role in α-cypermethrin, deltamethrin and fenvalerate detoxification in S. exigua.

In this study, a new surface molecularly imprinted polymer (SMIP) of teicoplanin (TEC) was prepared in an aqueous solution using amino-modified silica gel as a carrier. The molar ratio of the template molecule, functional monomer and cross-linker in the optimized synthesis system was 1 : 15 : 40. The structure and morphology of SMIP were characterized by Fourier-transform infrared spectra and scanning electron microscopy, respectively. It was shown that the silica gel modified with different active groups; the type and structure of functional monomers have a great influence on the specificity of SMIP. The SMIPs synthesized from a series of methacrylic acid and its hydroxylalkyl esters as functional monomers have good specificity for TEC. The results of static adsorption experiments showed that the adsorption capacity of SMIP was 6.5 times that of non-molecularly imprinted polymer, which were 152.6 mg g⁻¹ and 23.6 mg g⁻¹, respectively, indicating that SMIP had a larger affinity for TEC. Finally, the SMIP was successfully used as a dispersive solid-phase extraction adsorption material to selectively extract and enrich TEC from the water sample. The limit of detection of the proposed liquid chromatographic method for TEC was 5 μg L⁻¹.

Larvae of the polyphagous tobacco cutworm moth, Spodoptera litura (S. litura), encounter potentially toxic allelochemicals in food. It is therefore important for S. litura to produce detoxification enzymes such as cytochrome P450 monooxygenases (P450s). In this study, we have identified two novel cytochrome P450 genes of S. litura, named CYP321A7 and CYP321A9. Phylogenetic analysis indicated that they belong to the CYP321A subfamily. Expression levels of these genes at different development stages were determined by real-time quantitative polymerase chain reaction (PCR). The highest expression was found in the midgut and the fat body. Larvae fed with a diet supplemented with xanthotoxin or coumarin showed a strongly increased expression of CYP321A7 and CYP321A9 in the midgut and fat body as compared to larvae that consumed a control diet. In contrast, larvae consuming a diet containing aflatoxin B1 or quercetin did not induce the expression of these genes. CYP321A7 and CYP321A9 showed different expression profiles with respect to certain allelochemicals. For example, a diet containing cinnamic acid stimulated the expression of CYP321A9, whereas no changes were observed for CYP321A7. We suggest that the fine tuning of P450 gene expression is an important adaptation mechanism that allows polyphagous S. litura larvae to survive in a changing chemical environment.

This study aimed to prepare a molecularly imprinted monolithic extraction column (MIMC) inside a micropipette tip by situ polymerization with roxithromycin as the dummy template. The polymers possessed excellent adsorption capacity and class-specificity to multiple macrolide drugs. MIMC was directly connected to a syringe for template removal and for the optimization of extraction conditions without any other post-treatment of polymers. A liquid chromatography-tandem mass spectrometric method was developed for the selective microextraction and determination of macrolide antibiotics in animal muscles based on MIMC. High recoveries of 76.1–92.8% for six macrolides were obtained with relative standard deviations less than 10.4%. MIMC exhibited better retention ability and durability when compared with the traditional C18 and HLB cartridges. The proposed method shows a great potential for the analysis of macrolide drugs at the trace level in animal foodstuffs.

Nicotinamide adenine dinucleotide phosphate (NADPH)-cytochrome P450 reductases (CPRs) function as redox partners of cytochrome P450 monooxygenases (P450s). CPRs and P450s in insects have been found to participate in insecticide resistance. However, the CPR of the moth Spodoptera litura has not been well characterized yet. Based on previously obtained transcriptome information, a full-length CPR cDNA of S. litura (SlCPR) was PCR-cloned. The deduced amino acid sequence contains domains and residues predicted to be essential for CPR function. Phylogenetic analysis with insect CPR amino acid sequences showed that SlCPR is closely related to CPRs of Lepidoptera. Quantitative reverse transcriptase PCR (RT-qPCR) was used to determine expression levels of SlCPR in different developmental stages and tissues of S. litura. SlCPR expression was strongest at the sixth-instar larvae stage and fifth-instar larvae showed highest expression in the midgut. Expression of SlCPR in the midgut and fat body was strongly upregulated when fifth-instar larvae were exposed to phoxim at LC₁₅ (4 μg/mL) and LC₅₀ (20 μg/mL) doses. RNA interference (RNAi) mediated silencing of SlCPR increased larval mortality by 34.6% (LC₁₅ dose) and 53.5% (LC₅₀ dose). Our results provide key information on the SlCPR gene and indicate that SlCPR expression levels in S. litura larvae influence their susceptibility to phoxim and possibly other insecticides.