Relationships among mound size, worker body length, and bait transport in Solenopsis invicta

The red imported fire ant (Solenopsis invicta Buren) is an invasive pest that poses a serious threat to the ecological environment and agricultural production. Its foraging and bait-carrying behaviors have significant impacts on the effectiveness of bait-based control methods. To better understand the bait transportation patterns of S. invicta and provide a scientific basis for its management, field experiments were conducted with ant mounds of different sizes. A commercial bait formulation (Shujue ant bait, 0.1% indoxacarb) was applied to each mound, and the amount of bait transported by the ants was measured at 1 h intervals. The results showed that the amount of bait transported increased initially, then decreased, and finally ceased over time. The second hour after bait placement represented the peak transportation period, while transportation nearly stopped after 8 h. The daily maximum transportation amount increased with mound volume, basal area, and height, reaching a maximum value of 36.096 g when the mound volume, basal area, and height were 47623.3 cm³, 2551.3 cm², and 28 cm, respectively. Moreover, a significant positive correlation was observed between worker body length and daily maximum transportation amount. A mathematical model describing the relationship among mound size, worker body length, and daily maximum transportation amount was established, providing a theoretical reference for optimizing the efficiency of bait-based control strategies against S. invicta.