Characteristics of carboxymethyl cellulose-based composite films and their control effect on Myzus persicae

The waxy layer on plant leaf surfaces serves as a crucial physical barrier against piercing-sucking pests such as aphids. Inspired by this natural defense mechanism, we focused on Ningxia wolfberry and its primary pest, Myzus persicae, and developed a composite material capable of forming a protective film on wolfberry leaves. Subsequently, the physical properties of the material, its efficacy in controlling wolfberry aphids, and its impact on plant physiology and biochemistry were evaluated. By comparing the film-forming performance of nine different material combinations on wolfberry leaves, the optimal composite film material Y2L1 was selected. Y2L1 consists of carboxymethyl cellulose (Y2) as the primary film-forming matrix, compounded with silica (L1) and organosilicon additives. Its efficacy against aphids was assessed by artificially inoculating aphids following spray application. The material's structure, micromorphology, and light transmittance were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet spectrophotometry, respectively. The physiological and biochemical impacts on wolfberry plants were evaluated by measuring chlorophyll content, activities of antioxidant enzymes, malondialdehyde (MDA) content, as well as contents of soluble protein, total soluble sugars, and free amino acids. Y2L1 formed a continuous, dense, and transparent film on the leaf surface. The film significantly inhibited the population growth of aphids (P < 0.05), with the best control efficacy (77.8%) observed on the 6th day after application. The components of Y2L1 exhibited good compatibility, with SiO₂-NPs uniformly dispersed within the system, and the film transmittance (T) remained stable between 74.6% and 81.0%. Furthermore, compared to the control group, the Y2L1 treatment significantly reduced aphid consumption of soluble protein and total sugars in wolfberry leaves, while no significant effects were observed on chlorophyll content, the activities of SOD, CAT, and POD, or MDA content. The Y2L1 composite film material combines excellent film-forming ability with significant insect resistance, while demonstrating no significant adverse effects on wolfberry plants within the scope of this study. These findings highlight its excellent safety profile, making it a promising candidate for the green control of wolfberry aphids with broad application potential.