BACKGROUND The widespread use of chemical insecticides has resulted in the development of resistance in German cockroaches worldwide, and biopesticides based on entomopathogenic fungi as active ingredients have become a promising alternative strategy. Resistance can change many of the physiological and biochemical characteristics of insect pests, such as cuticle thickness, detoxification enzyme activity, and even intestinal flora composition. Thus, potential interactions between pathogenic fungi and insecticide resistance may lead to unpredictable changes in pest susceptibility to fungi. RESULTS Beta‐cypermethrin‐resistant German cockroaches were more susceptible to infection with the fungus Metarhizium anisopliae regardless of age and sex. Histopathological results showed that the infection of resistant strains (R) by M. anisopliae was visibly faster than that of susceptible strains (S). The gut microbiota of the S strain indicated a stronger ability to inhibit fungi in vitro. The abundance of Parabacteroides, Lachnoclostridium, and Tyzzerella_3 decreased significantly in the R strain, and most demonstrated the ability to regulate glucose and lipid metabolism, and antifungal infections. The expression levels of Akirin, BgTPS, and BgPo genes in the R strain were significantly lower than those in the S strain, while BgChi and CYP4G19 gene expression were significantly higher. The mortality of cockroaches infected with M. anisopliae decreased to varying degrees after RNA interference, reflecting the role of these genes in antifungal infection. CONCLUSIONS Results confirmed that insecticide resistance may enhance cockroach susceptibility to fungi by altering intestinal flora and gene expression. Fungal biopesticides have high utilization value in pest control and insecticide resistance management strategies. © 2021 Society of Chemical Industry.

In order to analysis force characteristics and changes of the anchor tension during the process of filling soil of the pull cantilever retaining wall, a model test is designed for research. The test mainly monitors basal earth pressure, lateral earth pressure of the retaining wall, anchor shaft force, lateral displacement of the retaining wall.

To solve the early destruction problems occurred when overlaying asphalt pavement structure containing semi-rigid base on broken cement concrete pavement, finite element software is used to compare the stress characters between the repaving pavement and ordinary pavement, and analyze the repaving structures under different loads and different road transverse grade. It shows that the value of compressive stress at the top of base of repaving pavement is significantly higher than that of ordinary pavement, meanwhile, its value of tensile stress of base bottom is lower; the asphalt surface and new base top of repaving pavement need to bare a high value of shear stress and compressive stress under overload, so it’s prone to splitting failure in the base. With the increase of transverse grade, both the shear stress difference of road surface and maximum vertical compressive at top of the base increase in a lower position, but the situation is opposite in the higher position.

There are many engineering diseases during asphalt road operating process caused by poor subgrade bearing capacity or pavement structural strength, mainly as the form of structural cracks, net-shaped cracks, subsidence, rutting. This phenomenon is more widespread in the level road whose structure form is rock filled sand or lime-flyash soil. Due to the engineering diseases of level road caused by poor subgrade bearing capacity or pavement structural strength, analyzing and comparing of various repair and reinforcement method, valve-pipe grouting technology is proposed. This paper revealed the grouting slurry diffusion and consolidation forming situation of the valve-pipe grouting technology.

Foundation pit excavation beside silt soil railway subgrade in the water net plain district is influenced by overload of backfilled roadbed, train's vibrating load and high groundwater level, so foundation pit instability occurs easily. Numerical simulation is done on several parameters such as different depths of pit cutting, distances from subgrade, speeds of the train, and so on. Through analyzing changes and impact ranges of the pore pressure and displacement under various work conditions, it reveals lateral deformation mechanism of the foundation pit. And also it provides references for supporting design of foundation pit beside silt soil subgrade.