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

## TL;DR

This study shows that Aquatica leii firefly larvae, especially in their 4th-instar stage, can effectively prey on the invasive Pomacea canaliculata snail, offering a potential eco-friendly control method.

## Contribution

The study identifies 4th-instar Aquatica leii larvae and their midgut extracts as highly effective biocontrol agents against Pomacea canaliculata.

## Key findings

- 4th-instar Aquatica leii larvae had the shortest lethal time (7.37 min) and highest consumption (1.23 g) of Pomacea canaliculata.
- Midgut extracts caused 96.7% mortality in Pomacea canaliculata, indicating potent bioactive compounds.
- Larvae accepted Pomacea canaliculata as prey, showing preference over native snails in controlled experiments.

## Abstract

The search for environmentally friendly ways to control the invasive Pomacea canaliculata has led scientists to look at its natural predators. This study focuses on the larvae of Aquatica leii, a freshwater firefly native to China. We wanted to see if these underwater larvae could effectively prey on the destructive Pomacea canaliculata. In our lab tests, not only did the firefly larvae successfully attack and eat the Pomacea canaliculata, but we also found that one particular growth stage—the 4th-instar larvae—was the most effective hunter, killing Pomacea canaliculata the fastest and consuming the most. A particularly notable finding was that liquid extracted specifically from the larval midgut exhibited strong lethal activity against P. canaliculata under experimental conditions, causing over 96% mortality. This suggests that the larvae may use potent injected toxins to subdue their prey, although further verification is needed. against the Pomacea canaliculata, causing over 96% mortality. This shows that the larvae likely use a powerful injected toxin to subdue their prey. Our research highlights Aquatica leii as a promising, natural candidate for biocontrol and suggests that its unique midgut toxin could be the key to developing new, targeted Pomacea canaliculata control products that are safer for the environment.

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.