Anthropogenic intensification on plant-pollinator interactions over four decades in Chile: a spatiotemporal assessment

Pollination is a key ecological interaction providing fundamental ecosystem services, as most food items we consume depend on biotic pollination. However, a pollination crisis has become evident in the last decades because of multiple anthropogenic biodiversity loss drivers. Agricultural expansion, agrochemicals, invasive species, and climate change are altering plant-pollinator interaction dynamics. Chile is a large food-producing country undergoing an 'anthropogenic intensification' as its economic development is being made at expense of its biodiversity. Based on a large database comprising four decades of plant-pollinator interactions, we used a network approach to characterize their spatiotemporal variation, considering two major events: the introduction of the exotic bumblebee Bombus terrestris in 2000 (becoming invasive), and the 2010-2020 megadrought that affected South-Central Chile. Most plant-pollinator records were concentrated in Central and South regions, where cultivated lands occur, while pollination studies in North and Patagonia regions are scarce and insufficient to perform further analyses. We analyzed 2108 interactions across time using four 10-year periods between 1980 and 2020. The most frequent plant families and pollinator orders changed over time, with hummingbirds and hoverflies more common before 2000 and bees afterward. We observed spatiotemporal changes in network specialization, modularity, and nestedness, matching B. terrestris introduction and the mega-drought. Modularity was significant in all cases, as non-random associations occurred between plant and pollinator groups, but it showed changes as exotic generalist bees became dominant. Analyzing historical data is a valuable tool to understand the effects of human activities on ecological interactions, and also to forecast future effects informing decision-making and providing evidence to prioritize conservation efforts.