The crown rot of wheat is a destructive soil-borne pathogen that severely reduces the yield and quality of wheat. This study aimed to screen and identify the antagonistic strains against Fusarium pseudograminearum (Fp), which is the dominant pathogen associated with the crown rot of wheat in China, and evaluate their biosynthetic potential. The antagonistic strains were screened via a dual-culture antagonism assay, and then identified by combining the morphological characteristics and internal transcribed spacer gene sequencing. The polyketide synthases (PKS-I and PKS-II) and non-ribosomal peptide synthetase (NRPS) genes in the antagonistic strains were detected via specific amplification of chromosomal DNA. Eleven out of 157 fungal strains, including six strains with matrix competition and five strains with antibiosis, were obtained. The eleven antagonistic strains belonged to the following four genera: Alternaria, Botryosphaeria, Phoma and Talaromyces. The inhibition rate of six strains with matrix competition was greater than 50%, with B. dothidea S2-22 demonstrating the highest at 80.3%. The width of the inhibition zone of T. trachyspermus R-17 among the five strains with antibiosis was the widest at 11 mm. Among the eleven antagonistic strains, three strains of A. alternata and the strain P. moricola only contained the PKS-II gene, the strain A. tenuissima contained PKS-I and PKS-II genes, three strains of B. dothidea contained PKS-II and NRPS genes, while three strains of T. trachyspermus did not contain any genes. These results demonstrated potential strains for the biocontrol of the crown rot of wheat. In particular, T. trachyspermus R-17 can be investigated further as a promising agent, and the active substances secreted by antagonistic strains may be synthesized by other pathways.

Purpose: Wheat sheath blight mainly infected by Rhizoctonia cerealis is one of the soil-borne fungal diseases of wheat worldwide and prevalent in major wheat growing areas in China at present. This study aimed to evaluate the antifungal activity of 163 endophytic fungi on R. cerealis. Antifungal strains were identified and their biosynthetic potential was analysed. Methods: The antifungal activity of the strains was evaluated via dual-culture antagonism assay. The antifungal strains were identified on the basis of morphological characteristics and internal transcribed spacer gene sequencing. The polyketide synthases (PKSs) and nonribosomal peptide synthetase (NRPS) genes in antifungal strains were detected via specific amplification of chromosomal DNA. Result: Twelve out of 163 fungal strains, including seven strains with matrix competition and five strains with antibiosis, were obtained. The twelve antifungal strains belonged to four genera: Alternaria, Ascochyta, Botryosphaeria, and Talaromyces. The inhibition rate of the seven strains with matrix competition was greater than 50%, with that of Botryosphaeria dothidea S2-33 being the highest at 84.6%. The inhibition zone of Talaromyces assiutensis R-03 amongst the five strains with antibiosis was the widest at up to 7 mm. Among the twelve antifungal strains, the strain S2-16 contained all the genes tested, five B. dothidea strains contained PKS-II and NRPS genes, two Alternaria alternata strains only contained PKS-II gene and the remaining four strains did not contain any. Conclusion: Results demonstrated twelve potential strains for the biocontrol of wheat sheath blight. In particular, T. assiutensis R-03 was determined as a promising agent. The active substances secreted by antifungal strains may be produced by other biosynthetic pathways.

In the scenario that requires the biological control of pests using predatory enemies, predators not only prey on pests directly but also can affect the population fitness of pests through indirect non-consumptive effects (predation risk effects). However, the impact of predation risk effects varies depending on the mode of stress imposed by natural enemies and the state of the stressed pests. Herein, we exposed aphids (Periphyllus koelreuteriae) at different stages to various cues from the multicolored Asian lady beetle (Harmonia axyridis) to assess the effects of different predation risks on P. koelreuteriae development and reproduction. We found that the effect of predation risk on aphid developmental time was clearly stage-dependent. When 1st-instar nymphs were exposed to predator cues, their developmental time was prolonged only in the early stages (1st–3rd instar nymphs). Similarly, when third-instar nymphs were stressed, only the current stage (third instar) showed a developmental delay, while fourth-instar nymphs and adult aphids were not significantly affected. Additionally, aphids at different stages perceive predation risk differently. Nymphs cannot recognize visual cues from predators, but can perceive odor cues. In contrast, adult aphids are sensitive to a variety of predator cues, including visual ones. Predation risk caused aphids to shorten their adult lifespan and reduce reproductive output, but it increased the proportion of diapause offspring. This study highlights the importance of considering how predation risk affects multiple life stages and physiological changes, which are important for gaining insights into the mechanisms of predator–prey interactions and for comprehensively assessing the ability of lady beetles to regulate aphid populations.

Purpose: Wheat sheath blight mainly infected by Rhizoctonia cerealis is one of the soil-borne fungal diseases of wheat worldwide and prevalent in major wheat growing areas in China at present. This study aimed to evaluate the antifungal activity of 163 endophytic fungi on R. cerealis. Antifungal strains were identified and their biosynthetic potential was analysed. Methods: The antifungal activity of the strains was evaluated via dual-culture antagonism assay. The antifungal strains were identified on the basis of morphological characteristics and internal transcribed spacer gene sequencing. The polyketide synthases (PKSs) and nonribosomal peptide synthetase (NRPS) genes in antifungal strains were detected via specific amplification of chromosomal DNA. Result: Twelve out of 163 fungal strains, including seven strains with matrix competition and five strains with antibiosis, were obtained. The 12 antifungal strains belonged to four genera: Alternaria, Ascochyta, Botryosphaeria and Talaromyces. The inhibition rate of the seven strains with matrix competition was greater than 50%, with that of Botryosphaeria dothidea S2-33 being the highest at 84.6%. The inhibition zone of Talaromyces assiutensis R-03 amongst the five strains with antibiosis was the widest at up to 7 mm. Among the 12 antifungal strains, the strain S2-16 contained all the genes tested, five B. dothidea strains contained PKS-II and NRPS genes, two Alternaria alternate strains only contained PKS-II gene and the remaining four strains did not contain any. Conclusion: Results demonstrated 12 potential strains for the biocontrol of wheat sheath blight. In particular, T. assiutensis R-03 was determined as a promising agent. The active substances secreted by antifungal strains may be produced by other biosynthetic pathways.

Sclerodermus guani Xiao et Wu, 1983 plays a significant role in the biological control of agricultural and forestry pests. To investigate whether different sugar types significantly affect the longevity, fecundity, and nutrient reserves of female S. guani adults, this study provided 1 mol/L solutions of sucrose, fructose, glucose, mannose, or trehalose under laboratory conditions, with a distilled water group serving as the control. The longevity and nutrient content of parasitoids were measured after varying feeding durations, while fecundity was assessed in preliminary experiments. The results demonstrated that prolonged sugar feeding significantly extended parasitoid longevity, with fructose, glucose, and sucrose exhibiting the most pronounced effects and no significant differences among them. Nutrient analysis revealed that sugar consumption significantly increased total carbohydrate content, slowed lipid depletion, and promoted protein accumulation. Sucrose, fructose, and glucose outperformed other sugars and the control in these aspects. Fecundity assays indicated that glucose and trehalose significantly shortened the pre-oviposition period and enhanced egg production. In conclusion, nutritional supplementation markedly improves the longevity and reproductive performance of S. guani, with 1 mol/L glucose identified as the optimal dietary source.