Predation risk of gregarious and aposematic insect larvae in an urban-agricultural landscape

Abstract

Predator–prey interactions are fundamental to ecosystem dynamics, as prey traits and environmental context jointly shape predation risk and predator behaviour. Preys have developed various strategies to evade predators with morphological adaptations like body colouration and behavioural changes to deter or escape their predators. Using an artificial caterpillar model, we tested the relationship between prey aggregation, body colouration, and the interplay of habitat structure with the likelihood of artificial prey being predated by visually oriented vertebrates within an urban-agricultural area in the Philippines. Of the 1026 observed prey items, 204 were attacked, primarily by mammals (75%), then birds (17%) and reptiles (8%). Contrary to our initial hypothesis, prey colouration did not influence predation risk. Instead, prey aggregation was the primary determinant of the likelihood of attack. Habitat structure variables also influenced predation. We suggest that predation risk is highest in aggregated prey, regardless of body colouration, challenging the expectations of aposematic effects in human-altered environments. This highlights the need to reassess predator-prey dynamics in these ecosystems, emphasise context-specific studies to understand ecological interactions, and call for further research on species interactions and environmental health indicators.