关键词: 药膜法, 挖沙活性, 最小驱避有效剂量

Abstract: The development of plant-derived repellents for red imported fire ants (Solenopsis invicta) plays an important role in breaking through the limitations of chemical synthetic agents in controlling S. invicta. We evaluated the repellent and contact activities of ethyl acetate extracts of five invasive plant species against S. invicta. The results showed that the extracts of the examined five species exhibited significant repellent activities using filter paper and sand-digging methods. In the membrane assay, the repellent grades of the five extracts against S. invicta were greater than or equal to level IV at 180 min, with the highest repellency grade of V observed for Praxelis clematidea and Solidago canadensis. In the sand-digging assay, the minimum repellent effective doses (MRED) of the extracts from the five species ranged from 0.01563 to 0.125 mg·g^-1. P. clematidea and S. canadensis showed the strongest repellent effects, with MRED of 0.01563 mg·g^-1 and 0.03125 mg·g^-1, respectively, equivalent to the positive control DEET with MRED of 0.0125 mg·g^-1, following by Cuphea hyssopifolia, Alternanthera philoxeroides, and Bougainvillea glabra with MRED all at 0.125 mg·g^-1. The extracts also displayed contact activity against S. invicta. After 72 h treatment, P. clematidea, C. hyssopifolia, and A. philoxeroides showed high toxicity, with LC₅₀ values of 0.1, 0.15, and 0.22 mg·cm^-2, respectively, all less than 0.5 mg·cm^-2; while B. glabra and S. canadensis exhibited relatively lower toxicity with LC₅₀ values of 1.06 and 1.20 mg·cm^-2, respectively. Our results indicated the repellent and contact potential of the five invasive plant extracts against S. invicta, especially P. clematidea. This study provides a reference for the use of invasive plants in the control of red imported fire ants.

Key words: film assay, sand-digging assay, minimum repellent effective dose