Two novel strains of actinobacteria, ZYC-3T and BH-SS-21T, were isolated from Hunan Province, PR China. The fermentation broth of BH-SS-21T inhibited the rapid spread of ginger blast, unlike that of ZYC-3T. The taxonomic characteristics of ZYC-3T and BH-SS-21T were defined using a polyphasic approach. The analysis of the full-length 16S rRNA gene sequence revealed that ZYC-3T and BH-SS-21T represented members of the genus Streptomyces . ZYC-3T had less than 98.7% sequence similarities to all species of the genus Streptomyces , while BH-SS-21T exhibited 99.97, 98.95, 98.83, 98.82, 98.75 and less than 98.7% sequence similarities to 'Streptomyces dioscori' A217, Streptomyces ederensis JCM 4958T, Streptomyces glomeroaurantiacus NBRC 15418T, Streptomyces aurantiacus NBRC 13017T, Streptomyces umbrinus JCM 4521T and other species with validly published names in the genus Streptomyces . However, the digital DNA–DNA relatedness and average nucleotide identity values between ZYC-3T, BH-SS-21T, and their closely related strains were significantly lower than the recommended threshold values. Also, phenotypic, chemotaxonomic and genetic features distinguished ZYC-3T and BH-SS-21T from their reference strains. On the basis of their genotypic and phenotypic characteristics, strains ZYC-3T and BH-SS-21T were classified as representing novel species of the genus Streptomyces under the names Streptomyces liliifuscus sp. nov. ZYC-3T (=CICC 25040T=JCM 34560T=MCCC 1K04978T) and Streptomyces liliiviolaceus sp. nov. BH-SS-21T (=MCCC 1K06236T=JCM 34767T), respectively.

The diamondback moth (Plutella xylostella) is one of the most destructive lepidopteran pests of cruciferous vegetables, and insights into regulation of its physiological processes contribute towards the development of new pesticides against it. Thus, we investigated the regulatory functions of its β-adrenergic-like octopamine receptor (PxOctβ3). The open reading frame (ORF) of PxOctβ3 was phylogenetically analyzed, and the levels of expression of the receptor mRNA were determined. This ORF was also cloned and expressed in HEK-293 cells. A series of octopamine receptor agonists and antagonists were tested against PxOctβ3. We showed that the receptor is a member of the Octβ3 protein family, and an analysis using quantitative PCR showed that it was expressed at all developmental stages of P. xylostella. Octopamine activated PxOctβ3, resulting in increased levels of intracellular cAMP. Furthermore, the agonists naphazoline, clonidine, 2-phenethylamine, and amitraz activated the PxOctβ3 receptor, and naphazoline was the most effective. Only metoclopramide and mianserin had significant antagonistic effects on PxOctβ3, whereas yohimbine, phentolamine, and chlorpromazine lacked obvious antagonistic effects. The injection of double-stranded RNA in an RNA interference assay indicated that PxOctβ3 regulates development in P. xylostella. This study demonstrated the pharmacological properties and functions of PxOctβ3 in P. xylostella, thus, providing a theoretical basis for the design of pesticides that target octopamine receptors.

Trehalase regulates energy metabolism in insects by converting trehalose into two glucose molecules. High amounts of trehalase are critical for insect flight and larval stress resistance. However, whether trehalase participates in the development of pesticide resistance remains unclear. In this study, we explored this phenomenon and the mechanism that underlies the regulation of Trehalase transcription. We found that overexpression of PxTreh1 and PxTreh2 induced Bacillus thuringiensis (Bt) resistance in Plutella xylostella. The promoter sequences of PxTreh1 and PxTreh2 were also cloned and identified. The dual-luciferase reporter system and RNA interference technology revealed that the expression of PxTreh1 and PxTreh2 genes is possibly regulated by the CCAAT enhancer-binding protein (C/EBPα). A yeast one-hybrid experiment confirmed the interaction between C/EBPα and the PxTreh2 promoter. The findings of this study suggest that C/EBPα mediates the adaptability of P. xylostella to adverse environmental stressors by regulating the expression of trehalase.

Background: Voltage-gated potassium channel Kv2 is the primarily delayed rectifier in insect nerves and muscles involved in several crucial biological processes, including action potential regulation, photoreceptor performance, and larval locomotor. It is a potential molecular target for developing a novel pesticide for mosquitos. However, there are few studies on the Kv2 channel in agricultural pests.Results: The only ⊍-subunit gene of the Kv2 channel in Plutella xylostella (L.), PxShab, was cloned, and its expression profile was analyzed. The relative expression level of PxShab was highest in the pupal stage of both sexes and male adults but lowest in female adults. Meanwhile, PxShab had the highest expression in the head in both larvae and adults. Then, PxShab was stably expressed in the HEK-293 T cell line. Whole cell patch clamp recordings showed an outward current whose current-voltage relationship conformed to a typical delayed-rectifier potassium channel. 20 ∼M quinidine could effectively inhibit the potassium current, while the channel was insensitive to 4-AP even at 10 mM. Several potential compounds and botanical pesticides were assessed, and carvedilol (IC 50 = 0.53 ∼M) and veratrine (IC 50 = 2.22 ∼M) had a good inhibitory effect on the channel. Conclusion:This study revealed the pharmacological properties of PxShab and screened out several high potency inhibitors, which laid the foundation for further functional research of PxShab and provides new insight into designing novel insecticides.

BACKGROUNDMating and oviposition are essential and closely coordinated events in the reproduction of moths. Although tyramine, a biogenic amine, can affect insect reproduction by binding its receptors, the specific regulatory mechanism has not yet been fully elucidated.RESULTSPlutella xylostella mutant with tyramine receptor 1 (TAR1) knockout (homozygous mutant with 7‐bp deletion, Mut7) was developed by the CRISPR/Cas9 system to investigate the effect of TAR1 knockout on the reproduction of the moth. Compared with wild‐type (WT), the egg yield of Mut7 female (Mut7F) was significantly lower, no significant difference was observed in the egg size and hatching ratio between the groups. Further analysis showed that TAR1 knockout adversely affected ovary development, characterized by shorter ovarioles and fewer mature oocyte. Additionally, TAR1 knockout significantly reduced the occurrence of mating, resulting in a decrease in egg yield in Mut7F. The amounts of sex pheromones were quantified using gas chromatography–mass spectrometry. Results showed that the amounts of sex pheromone released by Mut7F were significantly lower before mating. Correspondingly, the messenger RNA (mRNA) levels of sex pheromone biosynthesis enzymes, including acetyl‐CoA carboxylase (ACC) and desaturase (DES), were significantly lower in the Mut7F pheromone gland. The decreased sex pheromone biosynthesis in Mut7F, especially before re‐mating, may be related to the underexpression of pheromone biosynthesis‐activated neuropeptide (PBAN).CONCLUSIONOverall, this study investigated the effect of PxTAR1 on oviposition and mating of P. xylostella. We report for the first time that TAR1 knockout could reduce the sex pheromone biosynthesis. These findings provide insights for developing a novel integrated pest control strategy based on mating interference. © 2023 Society of Chemical Industry.