A Slow and Controlled Release Alginate Drug-Carrying Microsphere Camouflaged as Prey for Intelligent Red Fire Ants Control

The invasion of red fire ants seriously threatens ecosystems, agricultural production and human health. Currently, indoxacarb baits (IDC MBt) are commercially available in the market, however, the high alertness of red fire ants tends to limit their effectiveness. Herein, we prepared a calcium alginate microsphere bait loaded with indoxacarb (CA@IDC MBt) using the polysaccharide material sodium alginate (SA) as a raw material. The CA@IDC MBt had a particle size of 3.5 mm with an encapsulation rate of 88.6%. It is less likely to cause alertness of red fire ants because of slow-acting than IDC MBt. We investigated the recognition, contact, attack, and handling behaviors of red fire ants toward CA@IDC MB. Our findings showed that CA@IDC MBt significantly reduced venomous alkali content in red fire ants compared to other treatment groups. Similarly, CA@IDC MBt treatment reduced the S-transferase (GST), catalase (CAT), and superoxide dismutase (SOD) enzyme activities in red fire ants. The efficacy of the field experiment at 21 days was 100% higher than that of the commercial drug. Taken together, CA@IDC MBt has a good slow-release effect and has the potential to be used as a novel bait for red fire ants. The study can be used as a benchmark for pest control using polysaccharide materials to mimic prey and may provide new ideas for the green prevention and control of red fire ants.