Is antibiotic (mis)use an emerging ecological threat to wild insects?

Abstract

Antibiotic discovery revolutionized human healthcare and boosted agricultural productivity. The efficacy of this revolution is now being challenged however, as the release of antibiotic residues into soils and waterways promotes the evolution and spread of antibiotic resistance genes. There are signs that this antibiotic pollution also has ecological costs, including reduced insect health. Here, we assess this risk. We discuss where, when and how wild insects are exposed to antibiotics, the consequences of this exposure and crucially, if the concentrations that wild insects encounter are sufficiently high to trigger phenotypic responses. Data demonstrate that antibiotic residues reach concentrations in the field that can have phenotypic impacts in insects. These impacts include reduced health and foraging activity in pollinators, and improved survival in insect vectors of disease, demonstrating potential consequences for food-security and disease transmission. More generally, antibiotics can reduce insect stress resistance meaning that antibiotic pollution could elevate insect susceptibility to other stressors implicated in insect declines. We highlight gaps in our understanding of how antibiotic pollution affects wild insects and the ecosystem services they provide. These gaps urgently need to be filled, because global antibiotic use is rising. Crucially, we must determine how antibiotic residues in the field degrade or accumulate along food chains, and how field-realistic concentrations affect insects directly and via interactions with other environmental stressors. This will offer concrete insights into the consequences of rising antibiotic use for insects, and their broader societal and ecological impacts.