Don't Leave the Past Behind: How Larval Experience Shapes Pupal Antipredator Response in Aedes aegypti

Abstract

Animals use predation encounters or risk experiences to influence their future antipredator responses. Such carryover effects of predation can benefit them by enhancing their antipredator behaviour and thereby decreasing their risk of mortality through predation. Despite these fitness benefits, behavioural carryovers of predation past may not be a common phenomenon in complex life cycles. Complex life cycles pose a unique evolutionary and physiological challenge to behavioural carryovers since every life stage is distinct in morphology, physiology, and function. Each life stage of a complex life cycle is expected to evolve its independent response based on the real-time threat level and manage the trade-offs accordingly. Along with the evolutionary challenge, physiological barriers can hamper behavioural carryovers, especially in holometabolous insects, where we observe extensive tissue remodelling and developmental compartmentalisation. We investigated behavioural carryover in the holometabolous mosquito model system, Aedes aegypti. We asked whether predation risk during a life stage carries over to the subsequent stage, influencing its behaviour, or if the next life stage responds according to its threat environment. Aedes aegypti has four major stages- egg, larva, pupa, and adult. We examined the effect of predation-risk experience across larval and pupal stages. Larval and pupal stages differ in morphology, physiology and function. They share the same habitat and, therefore, similar threats. We manipulated the threat of predation experienced by larvae and investigated its influence on pupal behaviour. We found behavioural carryover in the pupal stage for the first time and discovered exciting interactions between past experiences and the current threat environment. Our study underscores the crucial role of predation pressure in shaping the evolution of complex life cycles, emphasising the significance of early experiences with predators in influencing behavioural traits across distinct life stages.