What is the fine-grained topic of the following text: Until now, birds got nearly all the credit for keeping organic coffee plantations where pesticides are banned insect-free, but a study from the University of Michigan has shown that during the summer wet season, bats eat more bugs than the birds at Finca Irlanda, a 740-acre organic coffee plantation in Chiapas, Mexico. Only return the topic.
Bats controlling pests in organic coffee plantations