Neustonic tadpoles do not detect and respond to insect predator

ABSTRACT

Prey animals use various signals to detect their predators and respond accordingly to enhance their survival. Since responding to a predator is costly, prey species may cut cost by using other strategies such as behavioural tactics, morphological changes, seeking natural refuge or unique habitat acquisition. Tadpoles of Microhyla nilphamariensis have a transparent body and live in a neustonic environment, which provides them protection against benthic predators. As a result, we investigated the predator detection mechanism in M. nilphamariensis tadpoles using different cues from an insect predator, dragonfly larvae, to determine if the presence of natural shelter and unique habitat acquisition influences the chemo-ecology of predator recognition in this species. We also exposed these tadpoles to active caged predators and a stress hormone, corticosterone (CORT) to study physiological mechanism underlying their behavioural anti-predator responses toward alarm cues. In the predator avoidance assay, M. nilphamariensis tadpoles did not respond to the predator using visual or chemical signals. The tadpoles did not change their activity in response to alarm, heterospecific, kairomones, and dietary cues released from the predator. Pre-conditioning of M. nilphamariensis tadpoles with caged predator and different concentrations of CORT also did not alter their activity in response to alarm cues. These results clearly demonstrated that neustonic tadpoles of M. nilphamariensis do not detect and respond to co-existing insect predator. We discuss these results in the context of unique habitat occupied by these prey tadpoles, the presence of alternate prey, and inherent factors such as transparent body.

KEYWORDS:

• Anti-predator behaviour
• corticosterone
• Microhyla nilphamariensis
• neustonic tadpoles
• predator detection

Acknowledgments

We thank Ms. Neha Pandhare and Ms. Ketaki Shetye for their help during experimentation and observations. The permissions to collect and maintain animals in the laboratory were obtained from the Maharashtra State Biodiversity Board (MSBB), Nagpur (MSBB/Desk-5/Appl/NOC/CR-275/1362/2015-16). In India, Indian researchers do not require permission to collect animals unless the locality of collection is in a wildlife protected area (The Gazette of India, REGD. NO. D. L. - 33004/99, section 17). Animal experimentations were performed following ethical guidelines established for animal usage by Savitribai Phule Pune University, Pune, India.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The majority of the data supporting the results or analyses presented in the paper itself. However, raw data can be made available on reasonable request to corresponding author.