Antifeedant and contact toxicity activity of crude extracts from 10 plants to red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae)

The red imported fire ant, Solenopsis invicta, is a destructive invasive pest that threatens ecological security in China. This study aimed to assess the bioactivity of ethanol crude extracts from 10 plants (Plectranthus hadiensis, Cnidium monnieri, Kaempferia galanga, Alpinia galanga, Perilla frutescens, Melia toosendan, Rosmarinus officinalis, Tripterygium wilfordii, Illicium verum, Scutellaria baicalensis) against S. invicta. The crude extract of K. galanga exhibited the strongest non-selective antifeedant activity at 50 mg/mL with an antifeedant rate reaching 52.67 % after 1 d of treatment. Additionally, the crude extract of R. officinalis showed the best selective antifeedant activity at 50 and 10 mg/mL with selective antifeedant rates of 69.33 % and 56.33 %, respectively. Furthermore, the results demonstrated that T. wilfordii exhibited excellent contact toxicity activity against S. invicta, with corrected mortality rates reaching 91.33 % and 98.00 % at 30 mg/mL after 1 and 2 d, respectively, and reaching 100 % mortality at 50 mg/mL. In conclusion, the crude extracts of K. galanga and R. officinalis displayed promising antifeedant activities against S. invicta while T. wilfordii showed potential as an alternative method for controlling this pest through its contact toxicity activity.