Keratin-functionalized nanomesoporous silica enhances indoxacarb efficacy against red fire ants

Feather keratin (FK) is a natural polymer material derived from discarded feathers with excellent modifiability and functionalization properties. However, the current applications in agriculture, especially in the development of nanopesticides targeting pest control, are still relatively limited. In this study, an insecticide controlled release system with pH and reduced glutathione (GSH) responsive properties was designed and prepared. The coating coverage was carried out by combining the carboxyl group of FK with aminated hollow mesoporous silica (HMS), which was loaded with indoxacarb (IDC) to obtain IDC@FK-HMS. IDC@FK-HMS had an average particle size of 178 nm, achieved a drug loading of 23.22 %, and exhibited superior thermal and photostability. Compared to IDC bait, IDC@FK-HMS bait has more significant insecticidal activity against red fire ants. The mortality of red fire ants fed with 8 mg/kg of bait for 72 h were 52.22 ± 1.92 % and 66.67 ± 3.34 %, respectively. In addition, IDC@FK-HMS had a more significant effect on the attack ability of red fire ants, which required more time to prey on yellow mealworms. IDC@FK-HMS was able to reduce the alertness and detoxification enzyme activity of red fire ants and enhance their sensitivity to insecticides, which in turn enhanced the insecticidal activity. FK-HMS encapsulation did not alter the toxic effects of IDC, both of which caused significant impacts on the midgut and acetylcholinesterase activity of red fire ants. The study enriched the avenues of application of FK in agriculture, especially in pest control, and provided new insights into the green and sustainable control of red fire ants.