Toward sustainable management of ant-hemipteran mutualism in agricultural settings: a comparison of different approaches

Mutualistic associations between ants and honeydew-producing hemipterans have a great ecological and evolutionary significance across terrestrial habitats but can also cause pest outbreaks in agroecosystems. At the same time, ants are often effective predators of several agricultural pests, can improve soil quality, and can control some plant pathogens. Neither ant attendance of hemipteran pests alone, nor a positive correlation between the abundance of ants and hemipterans automatically imply that ants are a worthy target or a key element in hemipteran management strategies. The main tactics in the management of ant-hemipteran associations in agroecosystems include the use of sticky or insecticidal barriers, low-toxicity baits, alternative sugary sources, or ant-adapted biocontrol agents. Barriers can quickly seal ground-nesting ants from the canopy of perennial plants but are unselective towards other arthropods and costly in terms of maintenance. Low-toxicity baits have been particularly tested against invasive and supercolonial ant species and yet are worth considering only when the complete elimination of ant colonies can be desirable. More recently developed and not yet widely available methods based on the provision of alternative sugary sources to manipulate ant behavior can allow to retain or even enhance the contribution of ants to the control of other phytophagous insects or plant pathogens while effective disrupting their mutualism with hemipteran pests. Finally, many parasitoids and predators possess specific adaptations to bypass attending ants, but the existence of species-specific factors complicatesthese networks. Further basic research and longer-term studies are needed to refine and improve the development of sustainable management strategies.