A bacterial strain BGI-1 was isolated from the gut of German cockroaches (Blattella germanica L.) and was identified as Bacillus subtilis based on 16S rDNA sequence and morphological, physiological, and biochemical characters. The strain BGI-1 inhibited the growth of Beauveria bassiana; the diameter of the inhibition zone exceeded 30 mm. Vesicles were observed in B. bassiana hyphae on the edge of the inhibition zone. Fermentation of BGI-1 reduced the conidial germination rate by 12%. Further studies demonstrated that B. bassiana infections in German cockroaches orally treated with the extracts of BGI-1 fermentation were significantly weakened. Cumulative mortality rate was 49.5% in the treatment group at the 20 d, while that of the control group was 62.3%. The study intends to understand the relationship between the intestinal flora and the cockroach. Those microbes with anti-entomopathogenic fungi activity might contribute to resisting the infection of pathogenic fungi.
Wheat take‐all, caused by the soil‐borne fungus Gaeumannomyces graminis var. tritici, is one of the major constraints on wheat production worldwide. Bacillus subtilis Z‐14 exerts significant biocontrol activity against wheat take‐all, and lipopeptide antibiotics are the main antifungal substances. Herein, lipopeptide antibiotics C14–C15 iturin A, C14–C16 fengycin A, and C15–C17 fengycin B from B. subtilis Z‐14 culture filtrates were separated and identified by high‐performance liquid chromatography, matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry, and mass spectrometry/mass spectrometry, respectively. The optimal medium components for Z‐14 lipopeptide antibiotic production were 3.85 g/L corn flour, 1.57 g/L soybean meal, 0.03 g/L FeSO4·7H2O, 0.2 g/L NaH2PO4·2H2O, and 0.4 g/L Na2HPO4·2H2O. Quantification analysis by high‐performance liquid chromatography showed that fengycins played a main role in antifungal activity against Gaeumannomyces graminis var. tritici. Quantitative reverse transcription polymerase chain reaction showed that lipopeptide synthesis genes fenD and ituC reached maximum expression levels after 48 h of fermentation. The strongest control of wheat take‐all by Z‐14 was achieved by adding 30 mL of culture filtrate per 350 g of soil in pot experiments, during which disease reduction reached 88.15%. This study provides theoretical support and a material basis for the prevention and treatment of wheat take‐all disease.
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.
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