“Get rid of them softly”: experimenting ecologisation of urban pest control practices with invasive ants

Résumé En

Ecologisation of pest control can be defined as the use of alternative techniques that are less toxic for the environment and human health. Along with other lethal and nonlethal methods, one strategy is to act on the ecological niche of target species in order to make it less favorable for their settlement. To do so, professionals mobilize knowledge on the biology, behavior and ecology of species in their environment. Implying changing perceptions of animals, these management strategies are often framed as a shift from “control of” to “coexistence with” wildlife in urban environments (Hunold & Mazuchowski, 2020). With a slightly different perspective, we would like to explore how knowing, caring and killing non-humans articulate in ecologised pest control, by focusing on professionals’ practices and invertebrate species.Our case study follows the discovery of ants Tapinoma magnum, considered as invasive, in the urban areas of Lausanne. We aim to explore how ecological experimental practices of pest control reconfigure relationships between ant biologists, pest controllers (called désinfestateurs in Romandie) and Tapinoma magnum ants. Our study is based on participant field observation, interviews and other written sources. After a brief description of the late discovery of the species and of actors involved in the public mandate for invasive species management, the communication examines professionals’ attempts to control the size and expansion of ant populations, focusing on its experimental dimension. First, we will describe the active collaboration between practitioners and scientists: how they adapt their respective rationale and knowledge practices in order to find what they define as an efficient strategy. We follow the different approaches they have tested and their adjustments between field and lab conditions. Second, we will analyse the ethic associated with this pest control experimentation, that reject undifferentiated eradication in favour of a long-term liveable reduction of invasive ant populations. Both practitioners and scientists assume the “killing” aspects of their mission and justify it by Tapinoma magnum species behaviour in urban conditions, in particular the nuisances caused by their proximity with inhabitants and their hypothetical threat for local biodiversity. Nonetheless, they develop careful practices that combine repetitive field observation, a contextual and parcimonious use of insecticides, and methods with a low toxicity for environment. Hence, this case study aims to provide a nuanced account of what ecologisation of pest control implies for relationships between professionals and animals, and to show the diversity of meanings and arbitrages that lethal management encompass in situation (see also Crowley et al., 2018).