PollinERA researchers Elżbieta Ziółkowska, Aleksandra Walczyńska (Jagiellonian University), and PollinERA coordinator Christopher John Topping (Aarhus University) have co-authored the newly published paper, The Formal Model for the hoverfly Eristalis tenax (Diptera, Syrphidae) agent-based model in the Animal Landscape and Man Simulation System (ALMaSS). This is PollinERA's second edition to the formal model, this time spotlighting Eristalis tenax, the common drone fly. Published in the Food and Ecological Systems Modelling Journal (FESMJ), this new model offers a detailed, individual-based simulation of one of the most widespread syrphid hoverflies, designed for use in Environmental Risk Assessment (ERA) of pesticides within the ALMaSS framework (Animal, Landscape and Man Simulation System).

Hoverflies are among the most important wild pollinators worldwide. However, as the paper notes, most existing individual-based models focus on aphid-eating species that provide pest control. Saprophagous hoverflies like Eristalis tenax, whose larvae feed on decaying organic matter, have remained underrepresented in environmental risk modelling. 

The authors state:

"To our knowledge, our model of E. tenax is the first spatially explicit individual-based model of a saprophagous hoverfly, linked with a detailed landscape model that provides a spatio-temporal assessment of food and habitat resources."

To address this gap, the paper presents a formal model of E. tenax for use in ALMaSS. The authors explain that the model was created to provide a realistic representation of a hoverfly pollinator with aquatic, saprophagous larvae in intensively managed European agroecosystems. 

"The initial application of the model is to provide a representative of this group for use in a systems-based approach to regulators risk amendment for pollinators impacted directly or indirectly by agrochemical use, primarily by pesticides."

The model simulates the full life cycle of E. tenax, from egg to adult, using an individual-based, spatially explicit approach. It runs within ALMaSS landscapes at a spatial resolution of 1 m² and daily time steps. Environmental drivers such as temperature, larval habitat distribution and quality, and the availability of nectar and pollen are factored into daily simulations. The model also accounts for foraging behaviour, dispersal, oviposition, and development, while tracking individual traits like age, location, pesticide loading, gut content, and reproductive status. 

The authors note that while the current model offers sufficient detail for initial regulatory use, it simplifies several biological processes. Energetic budgets and population genetics are not included in this version They recommend future development to incorporate sub-lethal effects, more complex internal toxicology models such as TKTD (toxicokinetic/toxicodynamic), and improved mapping of larval habitat conditions. Lastly, authors also emphasise the importance of calibration using a pattern-oriented modelling (POM) approach to align simulations with empirical data.

Read the full paper here.