Host plant phenology may determine the abundance of an ecosystem engineering herbivore in a tropical savanna

1. Variation in plant phenology allows plants to escape from herbivory. Insect herbivores manipulate their host plants by producing shelters, which they inhabit, and are protected against natural enemies and/or unfavourable environmental conditions. Environmental modifications induced by living organisms are characterised as ecosystem engineering. 2. In the Brazilian savanna, the interaction between the Malpighiaceae shrub, Byrsonima intermedia, and its main herbivore, the caterpillar Cerconota achatina, a shelter‐building organism, was studied. 3. It was focused on whether the phenological development of the host plant affects the caterpillars' infestation, and whether C. achatina acts as an ecosystem engineer by building shelters. All plant variables (number of leaves, flowers, buds, fruits and herbivores) were measured fortnightly. Phenological data were correlated with climatic information. The impact of the caterpillars acting as ecosystem engineers was measured experimentally. 4. Infestation levels of C. achatina covaried with the phenology of their host plant B. intermedia. It suggests that plant phenology might be an important factor in determining the abundances of this ecosystem engineer species.