The Central American acacia tree and the ant Pseudomyrmex ferrugineus live in a symbiotic relationship. The tree provides sweet nectar for the ants, and the ants protect the tree from weeds and animals. But we now know that the relationship is rather one-sided, as the tree not only causes the ants to become addicted to its nectar, but also damages the ants to make them unable to digest any other food! Martin Heil of Cinvestav Unidad Irapuato in Mexico studied the ants, and found that they are born with the ability to digest a variety of sugars, but then lose their invertase, an enzyme that breaks down sugars.
The disabled ants can then only survive on the partially-digested sugar of acacia nectar.
Heil has now shown that the tree itself is responsible. Writing in the Ecology Letters journal, he reports that acacia nectar contains chitinase enzymes that completely block invertase.
Shortly after the workers emerge from their pupae as adults, they take their first sip of nectar and their invertase becomes irreversibly disabled.
"Ain't nature grand?" says Todd Palmer of the University of Florida, who studies ants and acacias.
"What looks from the outside as another case of digestive specialization appears to be a sneaky manipulation on the part of the acacia to increase ant dependence."
That's kind of like a nefarious baby food company that offers to pay for your rotten teeth to be pulled instead of repaired. Like I've always said, never trust a tree bearing gifts. Read more about this research at NatGeo News.
(Image credit: Alexander L. Wild)