Experience window influences development and retention of memory to recognize predators in the larval skipper frogs

Learning and memory are critical for predator recognition as they allow prey species to develop an adaptive response to a novel situation, thus increasing their chances of survival. In prey species that lack innate predator recognition, alarm cues play a crucial role in learning by their association with novel predator odour. Perception of novel predator odours along with alarm cues allows the prey to learn to detect predatory odours alone in their future encounters. A single event of exposure is considered to be sufficient for the prey to associate predatory cues with alarm cues. However, the minimum time required for learning and memorizing information about predator identity is unknown. Hence we used the tadpoles of Euphlyctis cyanophlyctis to determine the association between the experience window and memory development and its retention. We conditioned tadpoles with a mixture of dragonfly nymph odours and alarm cues for 1, 3, 6, 12 and 24 h, and subsequently assessed their antipredator behaviour at different intervals. Our results show that the minimum duration required for associative learning is ~6 h. Interestingly, the intensity of antipredator response was proportional to the duration of conditioning. Moreover, retention of memory increa­sed with an increase in the duration of conditioning. Hence, we show the significance of conditioning duration in learning. We also show an association between the duration of conditioning and retention of memory. In aquatic ecosystems, where the prey encounters a wide array of predatory cues, our findings open a new avenue for understanding the complexities associated with learning and the development of memory.