Attract and distract: Alternative sugars disrupt the ant-hemipteran mutualism and improve biological control

Ants can act simultaneously as predators and as protectors of honeydew producing pests. Thus, their role regarding plant protection can be positive or negative. Due to their protecting behaviour towards honeydew producers ants interfere with the activity of natural enemies and often are becoming important indirect pests. For that reason, ant-exclusion is employed to reduce the risk of population outbreaks of honeydew producing pests. By excluding ants however we also lose their services as biocontrol agents.

The mixed Biobest-UPV-INRA R&D team has tested the potential of artificial sugar supplements to disrupt the ant-pest interaction and eventually improve the control of aphids and mealybugs in citrus and vineyards in Spain. Concretely, they assessed whether the provisioning of artificial sugar sources :

• impacts ant activity
• disrupts the association between the ants and the aphids or the mealybugs
• reduces the pest populations

Results show that the provisioning of sugars can alter ant activity, reduce the ant tending incidence and the colony size of the honeydew producers and finally significantly increase the probability of natural enemies being associated with the honeydew producers.

In conclusion, it would seem that provisioning of artificial sugar sources has practical potential as strategy for ant management in support of biological control honeydew producing herbivores.