Preliminary Investigation into the Predation of Pomacea canaliculata by Aquatica leii Larvae

Pomacea canaliculata, a pervasive invasive gastropod, inflicts significant ecological and economic damage in Chinese rice ecosystems. With the limitations of chemical molluscicides, sustainable biological control solutions are urgently required. This study presents a comprehensive investigation into the biocontrol potential of larvae of the endemic aquatic firefly, Aquatica leii, against Pomacea canaliculata. Through controlled laboratory experiments, we evaluated the feeding preference of larvae when offered a choice between Pomacea canaliculata and a native snail (Cipangopaludina chinensis), and systematically quantified the predatory efficiency (lethal time and consumption amount) across the 3rd to 6th larval instars. Furthermore, the lethal activity of crude extracts from distinct anatomical regions of the larval digestive tract (mouthpart, foregut, midgut, and hindgut) was assayed via injection into Pomacea canaliculata. The larvae accepted Pomacea canaliculata as a viable prey source. Predatory performance varied markedly among instars; 4th-instar larvae exhibited optimal efficacy, characterized by the shortest mean lethal time (7.37 min) and the highest mean consumption (1.23 g). Midgut extract was identified as the principal causative agent of mortality, inducing a 96.7% mortality rate in Pomacea canaliculata, which was significantly superior to the minimal effects observed from other extract types. This points to the midgut secretion as a likely source of potent bioactive compounds responsible for rapid snail lethality, warranting further investigation. responsible for rapid snail lethality. Our results conclusively demonstrate, from both behavioral and physiological vantage points, the feasibility of Aquatica leii larvae as a highly effective native biocontrol agent. This work establishes a critical foundation for future research aimed at the isolation and characterization of the midgut-specific active substances, paving the way for the development of novel, target-selective biogenic molluscicides.