Eggs of the freshwater snail Pomacea canaliculata (Caenogasteropoda: Ampullariidae) are defended against avian and insect predation.

DREON, MARCOS SEBASTIÁN; HERAS, HORACIO; BROLA, TABATA ROMINA; GIROTTI, JUAN R.; SOLDATI, KEVIN BRIAN; FERNANDEZ, PATRICIA E.

Posadas

Congreso; 4o Congreso Argentino de Malacología (4CAM); 2022

Asociación Malacológica Argentina

The invasive snails Pomacea canaliculata have been introduced worldwide causing serious problems. Though they lay their eggs above water as conspicuous masses exposed to different predators, they have almost no reported predators. The egg perivitelline fluid (PVF) not only provides nourishment, but it also protects embryo with proteins, hereafter perivitellines, that conform a unique defence system against predation. We recently demonstrate the toxic effect of the PVF against rodent and amphibian. The aim of this work was to expand this knowledge to other taxa evaluating the toxicity of the PVF, and the neurotoxic perivitellin PcPV2, on birds (Coturnix coturnix) and insects (Tenebrio molitor). To evaluate the PVF lethality on quails, groups of five animals were intraperitoneally injected with 200μL of PVF serial dilutions (1.7-28mg/kg) and lethality observed for 96h. A LD50 of 7.4 mg/Kg was determined. To analyse the effects on the small intestine, 3 quails were 24h and 48h gavaged with 500μL PVF (8mg/mL) and euthanized 24h after the last administration for histological examination. In 24h group, villi showed degeneration and death of enterocytes. Hyperemia of the villus arteriole and subepithelial edema were also observed, together with lymphocyte infiltration, mononuclear cells, and some eosinophils in the lamina propria. These effects diminished in 48h group. For insect toxicity tests, 2 groups of 10 animals were injected with 5μL of PVF (1,89±0,15g/L) and PBS and inspected daily for lethality. Additionally, groups of 10 insects were injected with serial dilutions of purified PcPV2 (0,5-5mg/L). The PVF toxicity was confirmed reaching a 30% of mortality while a LD50 of 2.42mg/mL determined for the neurotoxin. These results indicate that, Pomacea eggs are lethal toward birds and insects and alter bird gut morphophysiology, extending the range of potential targets of their defensive system to another vertebrate order and, for the first time, to invertebrates.