Hardship Strengthens Mutual Bonds
Ants patrol Cordia alliodora trees for caterpillars and leaf-eating insects, biting them until they leave.
Tiny sap-sucking insects that are a scourge to gardeners also have the upside of helping trees survive in seasonally dry forests in Central America. How? Scale insects use carbon they get from Cordia alliodora trees to make sugar-rich “honeydew” for Azteca pittieri ants, which in turn defend the trees against leaf-munching insects. Mutualism is often stronger when resources are scarce, but this interdependence usually involves a commodity that is traded directly between species.
Now, a new study shows that lack of a resource that is not traded—water—intensifies the bonds between C. alliodora, scale insects, and ants… (more)
PLOS Biology 2013