Yingtong Chen

Pomacea canaliculata, as an invasive exotic species in Asia, can adversely affect crop yields, eco-environment, and human health. Application of molluscicides containing metaldehyde is one effective method for controlling P. canaliculata. In order to investigate the effects of metaldehyde on adult snails, we conducted acute toxicological experiments to investigate the changes in enzyme activities and histopathology after 24 h and 48 h of metaldehyde action. The results showed that the median lethal concentrations (LC) of metaldehyde on P. canaliculata were 3.792, 2.195, 1.833, and 1.706 mg/L at exposure times of 24, 48, 72, and 96 h, respectively. Treatment and time significantly affected acetylcholinesterase (AChE), glutathione S-transferase (GST), and total antioxidant capacity (TAC) activity, with sex significantly affecting AChE, GST, and TAC activity and time significantly affecting carboxylesterase (CarE). In addition, the interaction of treatment and time significantly affected the activity of GST, CarE and TAC. In addition, histopathological changes occurred in the digestive glands, gills and gastropods of apple snail exposed to metaldehyde. Histological examination of the digestive glands included atrophy of the digestive cells, widening of the hemolymph gap, and an increase in basophils. In treated snails, the hemolymph gap in the gills was widely dilated, the columnar cells were disorganized or even necrotic, and the columnar muscle cells in the ventral foot were loosely arranged and the muscle fibers reduced. The findings of this study can provide some references for controlling the toxicity mechanism of invasive species.

Apple snails (ASs), the freshwater snails of the family Ampullariidae, are widely spread in tropical and subtropical regions. Owing to their strong invasiveness and harmful effects on agricultural production and ecosystems, they have attracted considerable attention. However, less research has been conducted on the whole picture of the current research status and development trends in the ASs field. For this purpose, we conducted a bibliometric analysis based on a total of 1028 publications regarding ASs published between 1900 and 2021 using VOSviewer 1.6.18 and CiteSpace 6.1.R3 software. The results suggest that ASs research has received increasing attention in recent years. The most productive country has been the USA, while the institution with the most publications was Consejo Nacional de Investigaciones Científicas y Técnicas Conicet. “Zoology” was the category of the most popular subject, Journal of Molluscan Studies was the primary journal, and P.R. Martin was the most outstanding author in ASs field. Invasive alien species, alarm response, copper (Cu) exposure, taxonomy and phylogenetic analysis, Angiostrongylus cantonensis (parasite), control (including molluscicidal activity), growth and reproduction, and feeding preferences were the main research hotspots. Further, “Pomacea maculata”, “Evolution”, “Biology”, “Digestive gland”, “Phylogeny”, “Identification”, “Pomacea canaliculata caenogastropoda”, “Diversity”, and “Nonnative apple snail” have been emerging active topics in recent years. These findings can help researchers in this area to better understand the direction and advances of ASs research and are valuable for future research and agricultural practice of apple snail control.

As the frequency of droughts increases with climate change, the tolerance of aquatic organisms to abiotic stressors will become critical determinants of survival. Pomacea canaliculata has become a widely distributed agricultural and environmental pest in southern China. To evaluate their tolerance and adaptation under the drought condition, the survival, feeding, behavior, and antioxidant system changes in female and male P. canaliculata were investigated during drought stress and rewatering process through an indoor simulation experiment. The results showed that female snails laid eggs before burrowing into the soil to ensure offspring reproduction. Female P. canaliculata had higher survival rates than males under drought stress, and their recovery ability of activity after rewatering was also superior to those of males. The antioxidant system of P. canaliculata showed obvious activation with gender differences after rewatering. Overall, the survival rate of female P. canaliculata was higher after drought stress, and the resilience ability of female snails after rewatering was stronger, including in their behavior, feeding, and antioxidant system recovery. The P. canaliculata tolerance to drought and the ability to recover quickly after drought may contribute to their long-term survival and facilitate continuous invasion.