Mangrove Against Invasive Snails: <i>Aegiceras corniculatum</i> Shows a Molluscicidal Effect on Exotic Apple Snails (<i>Pomacea canaliculata</i>) in Mangroves

Apple snails (<i>Pomacea canaliculata</i>), one of the 100 most serious invasive species in the world, have invaded mangrove wetlands due to their salinity tolerance. We firstly prepared a plant molluscicide against apple snails based on the mangrove <i>Aegiceras corniculatum</i> in coastal wetland. The effects of four mangrove extracts from <i>A. corniculatum</i>, including ethanol extract (EE), petroleum ether extract (PEE), ethyl acetate extract (EAE), and n-butanol extract (BE), were studied for molluscicidal activity against apple snails in a saline environment. The LC₅₀ values at 48 h of EE, PEE, EAE, and BE were 25 mg/L, 123 mg/L, 170 mg/L, and 14 mg/L, respectively. BE had the highest molluscicidal value (96.7%) against apple snails at 48 h. At 48 h, BE of <i>A. corniculatum</i> leaves significantly decreased the soluble sugar content, soluble protein content, acetylcholinesterase, and glutathione of apple snails to 4.25 mg/g, 29.50 mg/g, 947.1 U/gprot, and 6.22 U/gprot, respectively, compared to those in the control. The increased BE concentration significantly enhanced the malondialdehyde and aspartate aminotransferase contents to 4.18 mmol/gprot and 18.9 U/gprot at 48 h. Furthermore, the damage in the hepatopancreas tissue of apple snails increased, and the cellular structure became necrotic as the concentration of BE from <i>A. corniculatum</i> increased. The content of palmitic acid in BE of <i>A. corniculatum</i> leaves was the highest (10.9%), possibly be a toxic ingredient against apple snails. The n-butanol extract of <i>A. corniculatum</i> leaves showed a potential to control apple snails in the brackish water, and its plantation was beneficial to control the further spread of apple snails in mangrove wetlands.