Testing the potential for ant predation of immature coffee berry borer (Hypothenemus hampei) life stages

The coffee berry borer (CBB) is a devastating pest of coffee around the world. One potential control strategy is to conserve habitat for natural enemies of CBB in coffee agroecosystems so they can better suppress populations of this pest. Ants predate adult CBB and reduce infestation levels on coffee plants, but few experiments have tested their ability to consume immature CBB inside of fruits. This could prove an important part of controlling CBB populations since berries house many immature individuals on coffee plants during and between growing seasons. Here we experiment with Wasmannia auropunctata and Solenopsis picea, two species of ants that are commonly found nesting and foraging on coffee plants in southern Mexico. We performed a predation experiment in the laboratory, where ant nests of each species were exposed to CBB larvae and pupae extracted from fruits and removal rate was recorded over time. We also tested the ants' ability to enter CBB galleries in infested coffee fruit. We found that both ant species removed CBB immature individuals in the laboratory, but that W. auropunctata removed them significantly faster than S. picea. While both species showed increased activity after exposure to infested fruits, only W. auropunctata maintained activity around fruits and readily entered CBB galleries in fruits, despite documenting this behavior with S. picea outside of experimental trials. These results suggest that some ant species, which forage on coffee and are small enough to enter CBB galleries, have potential to contribute to biocontrol by consuming immature CBB inside infested fruits. However, further experiments in the field under realistic conditions will be needed to fully estimate this effect.