Manipulated ants: inducing loyalty to sugar feeders with an alkaloid

Abstract

BACKGROUNDWood ants are promising biocontrol agents in fruit plantations as they prey on pest insects and inhibit plant diseases. However, these ants also attend plant‐feeding homopterans to harvest their honeydew secretions thereby increasing their numbers. This problem can be solved by offering ants alternative sugar sources that are more attractive than honeydew. From natural interactions, it is known that some species manipulate mutualistic partners to loyalty by adding alkaloids to the food they offer their mutualists. Inspired by this, the addition of alkaloids might be used to make ants loyal to artificial sugar feeders and thus used to reduce populations of ant‐farmed homopterans in ant mediated biological control. We aimed to explore if wood ants (Formica polyctena) would develop a taste preference to morphine containing sugar solutions in two‐choice laboratory tests.RESULTSAfter having fed on a morphine/sugar solution for one week, ants showed a significant preference for morphine solutions compared to equally concentrated sugar solutions without morphine. Furthermore, ants lost this preference after six to nine days on a morphine‐free diet.CONCLUSIONThe results show that wood ants react to morphine in their food, enabling a chemical manipulation of their behavior most likely through a taste preference. Thus, ants are susceptible to manipulations by mutualistic partners in natural interactions and furthermore may be manipulated artificially in biocontrol programs to avoid ant mediated build‐up of homopteran populations.This article is protected by copyright. All rights reserved.