Shell-shocked: parasite-induced behaviour and development in an invasive dead-end snail host.

Area of Science:

• Ecology
• Parasitology
• Invasive Species Biology

Background:

• Parasites with complex life cycles rely on numerous infectious stages for transmission.
• Dead-end hosts, unable to support parasite development, are traditionally viewed as ecological endpoints.
• Invasive species may experience significant ecological consequences from non-transmissive parasite infections.

Purpose of the Study:

• To investigate the sublethal effects of Paragordius varius hairworm larvae on the behavior and development of the invasive freshwater snail Physella acuta.
• To determine if dead-end host infections impose ecologically significant costs on Physella acuta.

Main Methods:

• A dose-response experiment exposed juvenile Physella acuta to varying concentrations of Paragordius varius larvae.
• Snail activity, including home range and water use, was monitored over 24 hours.
• Shell development and physical properties were assessed post-exposure.

Main Results:

• Infection intensity correlated with larval dose.
• High parasite exposure reduced snail home range by nearly one-third and altered water usage patterns.
• Shell crush resistance significantly increased with parasite dose, despite no changes in shell size or shape.

Conclusions:

• Parasite exposure imposes sublethal, ecologically significant costs on dead-end hosts like Physella acuta.
• These findings challenge the traditional view of dead-end hosts as passive recipients, highlighting their role in host-parasite dynamics.
• Non-transmissive infections can have fitness and ecological consequences for invasive species.