A research team at South China Agricultural University has successfully developed a drug‑delivery system that enables the precise intestinal delivery of thiamethoxam to red imported fire ants.

Release Date:

2024-12-23

Recently, the College of Plant Protection at South China Agricultural University and the National Key Laboratory of Green Pesticides have successfully developed a drug‑delivery system that enables precise release of pesticides within the gut of red imported fire ants. The findings were recently published in the Chemical Engineering Journal.

The first author of the paper, Liu Pengpeng, stated that the study synthesized a lignin‑modified copper‑based metal–organic framework (L/HKUST‑1), which addresses the shortcomings of the conventional copper‑based metal–organic framework (HKUST‑1). This led to the development of a pH‑responsive pesticide delivery system (TMX@L/HKUST‑1) that, by responding to the acidic microenvironment in the midgut of red imported fire ant workers, achieves precise delivery of thiamethoxam (TMX) within the ant’s gut and significantly enhances TMX’s insecticidal efficacy against red imported fire ants.

This study achieved the green and rapid synthesis of a copper-based metal–organic framework, L/HKUST‑1, with an octahedral structure, via a one-pot method using alkali-treated lignin. The resulting material exhibits an average particle size of 530 nm and, compared with conventional copper-based metal–organic frameworks, demonstrates superior water stability and drug-loading capacity. In the acidic gut environment of red imported fire ant workers, TMX@L/HKUST‑1 particles disintegrate, releasing thiamethoxam.

Furthermore, TMX@L/HKUST-1 increased the consumption of sugar water containing thiamethoxam by red imported fire ants, caused intestinal damage in worker ants, and significantly enhanced insecticidal activity. It also inhibited key enzymes involved in detoxification and oxidative stress responses in red imported fire ants, including carboxylesterase, acetylcholinesterase, polyphenol oxidase, superoxide dismutase, and peroxidase. Additionally, it reduced the relative abundance of Serratia in the ant gut while increasing the relative abundances of Pseudomonas and Bacillus; these shifts in microbial community composition impaired the ants’ nutrient absorption, energy metabolism, and stress resistance. This study has developed a drug‑delivery system that enables precise release of pesticides within the red imported fire ant gut, offering a novel approach to the green management of this pest.

Relevant paper information: https://doi.org/10.1016/j.cej.2024.158644

Source: China Science Daily

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