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Lentinan (LNT) is a natural and functional polysaccharide isolated from Lentinus edodes fruiting bodies, which functions in stimulating the plant immune response, improving plant disease resistance and regulating plant growth. This study explores the use of LNT as a plant growth regulator and attractant in cotton production. After treatment with LNT, the content of malondialdehyde (MDA) in cotton seeds decreased, whereas the activities of polyphenol oxidase (PPO), superoxide dismutase (SOD) and peroxidase (POD) in leaves increased significantly. LNT also promoted the growth and development of cotton plants and significantly reduced the incidence of cotton damping-off disease. The relative expression of salicylic acid pathway-related genes in cotton also increased significantly. The prevention mechanism of fluopimomide was also evaluated, and the result showed lower EC50 values and was effective in controlling cotton seedling disease caused by Rhizoctonia solani in both greenhouse experiments and field trials. The use of LNT and fluopimomide in controlling cotton seedling damping-off disease showed a synergistic effect in field trials. These results will provide a new insight into the agricultural application of LNT as a biological fungicide in the field of biological controls.

Ganoderma lucidum polysaccharide (GLP), which is the primary active ingredient in G. lucidum, has been widely used in functional food and clinical medicine. However, it is rarely reported in the prevention and control of plant diseases. In this study, we found that the GLP can increase the germination rates and seedling heights of maize and wheat. We also found that the combination of GLP and chemical fungicides as a seed coating chemical compound has a control effect of more than 75% on the primary soil-borne diseases of the wheat and maize growing areas in both greenhouse and field trials. Furthermore, the combination of GLP and chemical fungicides prolongs the lasting period and reduces the application dosage of the chemical fungicides by half. In addition, GLP seed dressing could increase the resistance-related gene expression of the TPS and WRKY53 in maize and WMS533, NbPR1a, and RS33 in wheat. The combination of GLP and low-dose chemical fungicides proved to be an effective way to effectively prevent wheat sharp eyespot, root rot, and maize stalk rot in the wheat and maize continuous cropping areas in the North China Plain and to reduce pesticide use and increase crop yield.

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Silkworm Bombyx mori (L.) (Lepidoptera: Bombycidae) is a critical insect for silk producers, but the inappropriate application of insecticides negatively affects the physiology and behavior of silkworms. This study found that the effects of neonicotinoid insecticides applied using two spraying methods on the growth and development of silkworms were different: the median lethal concentration (LC50) values of two pesticides applied using the leaf-dipping method were 0.33 and 0.83 mg L−1 and those of two pesticides applied using the quantitative spraying method were 0.91 and 1.23 mg kg−1. The concentration of pesticides on the mulberry leaves did not decrease after their application using the quantitative spraying method, and a uniform spraying density was observed after the mulberry leaves were air-dried (no liquid) under realistic conditions. We then treated silkworms with the quantitative spraying method and leaf-dipping method. The treatment of silkworm larvae with imidacloprid and thiamethoxam at sublethal concentrations significantly prolonged the development time and significantly decreased the weight and pupation rate, as well as economic indicators of enamel layers and sputum production. Thiamethoxam treatment significantly increased the activities of carboxylesterase (CarE) and glutathione-S-transferase (GST). The activity of CarE and GST increased, decreased, and then increased, and the highest activity was detected on the 10th and 12th days. Thiamethoxam exposure significantly elevated the transcription levels of CarE-11, GSTe3 and GSTz2 and induced DNA damage in hemocytes. This study confirmed that the quantitative spray method is more stable than the leaf-dipping method. Moreover, imidacloprid and thiamethoxam treatment affected the economy and indexes of silkworms and induced changes in detoxification enzymes and DNA damage in silkworms. These results provide a basis for understanding the mechanism of the sublethal effects of insecticides on silkworms.