leafing phenology and insect seasonality in an ever-wet tropical forest

Seasonal patterns in tropical insect communities remain poorly understood because temperature is rarely limiting to growth or reproduction in tropical climates. In these regions, insect seasonality is often attributed to rainfall, yet distinct seasonal dynamics also occur in ever-wet forests where climatic fluctuations are minimal. Here, we examine the seasonality of abundance and diversity in lepidopteran herbivores associated with the tropical tree genus Inga in Yasuní, an aseasonal lowland rainforest in the Ecuadorian Amazon. We find that both leaf production and herbivore communities show pronounced seasonal peaks during the driest and brightest months of the year. Using structural equation modeling, we evaluate the relative roles of climate and leaf production in shaping insect seasonality and find support for both pathways. Finally, we show that communities feeding on expanding versus mature leaves differ strongly in composition, with expanding leaves supporting more specialized and phylogenetically divergent herbivore assemblages. Together, these results demonstrate that even in an ever-wet tropical forest, subtle climatic cues and host phenology interact to drive pronounced insect seasonality