Khubaib Shakoor 1,2, Umar Imtiaz 1,2, Deguan Tan 1* and Jiaming Zhang 1,2*
1College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China; 2Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Science, Hainan, China
*Corresponding author: zhangjiaming@catasitbb.cn (JZ); tandeguan@catasitbb.cn (DT)
The invasive apple snail, Pomacea canaliculata, poses a serious threat to duckweed-based agricultural systems due to its heavy grazing. Despite this risk, there is limited quantitative information on the extent of damage caused by this species and on practical methods to reduce its impact. In this study, we investigated the feeding behavior of P. canaliculata on duckweed and evaluated potential mitigation strategies under controlled laboratory conditions. Snails collected from Haikou, Hainan Province, China, were identified using a combination of morphological characteristics and molecular analyses of mitochondrial COI and 16S rRNA genes, confirming their species identity. A series of feeding experiments was conducted to examine how starvation duration, temperature, duckweed surface density, duckweed species (Spirodela polyrhiza and Lemna aequinoctialis), and snail body weight influenced grazing intensity. The results showed that food consumption increased markedly with longer starvation periods, reached its highest level at moderate temperatures, and was greater when duckweed surface density was low. Snails consumed significantly more L. aequinoctialis than S. polyrhiza, and larger individuals exerted substantially higher grazing pressure than smaller ones. In addition, protective experiments evaluated the effectiveness of different concentrations of nutritional medium (E-Medium), niclosamide, and tea saponin in reducing snail damage. All treatments reduced grazing activity and promoted duckweed biomass in a concentration-dependent manner. However, high concentrations of niclosamide and tea saponin caused noticeable phytotoxic effects on duckweed, even in the absence of snails. Moderate concentrations provided the best balance between effective snail control and duckweed preservation. Overall, this study demonstrates the severe impact of P. canaliculata on duckweed cultivation and emphasizes the importance of integrated management strategies that combine ecological understanding of snail feeding behavior with carefully optimized control measures to ensure sustainable duckweed production.