16th Century Spanish Trade Routes Between Acapulco and Manila (image) University of Illinois at Urbana-Champaign Share Print E-Mail Caption Soil was loaded onto Spanish galleons traveling from Acapulco, Mexico, to Manila, Philippines, in the 16th century. The soil, needed for ballast on empty vessels, likely also included tropical fire ants, researchers report. Credit Julie McMahon Usage Restrictions Credit required: Julie McMahon Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.