These ants herd bugs, the way the we herd cattle. And their agricultural endeavours are destroying our chocolate.
Cattle graze on pastures, but these mealybugs raised by the ants graze on sap from the cocoa tree — yup, the one that gives us cocoa beans and chocolate. By feeding on the sap these ant-harvested bugs kill the cocoa pods.
The ants get fed from the mealybugs suggary secretions. And Ghanaian cocoa farmers are not happy about it.
Mealybugs "look like woodlice dipped in flour," according to Ed Yong, who wrote about these ants and other plant infections in aeon.
Before the cocoa trees came along, the mealybugs drank from native rainforest trees. But as the rainforests have been cleared and non-native cocoa tree farms started to dominate the landscape, "the ants adapted, by driving their livestock into the fresh cocoa pastures," wrote Yong.
Mealybugs usually cause little harm to local trees, but the cocoa isn't protected against the virus used by the mealybugs to eat from the trees. The cocoa trees swell and eventually die.
But there's more. The ants, "strip cocoa pods to build tents for themselves and their mealybugs," writes Yong. The cocoa pods can't handle the stress of infection and occupation — leaving them plagued with parasites and sometimes turning them black.
The cocoa plants, already weakened by the virus, are easily rattled by the disease.
You may not have thought about it but plant diseases like this are devastating.
"We lose 40 per cent of the plants destined for our dinner tables to parasites," wrote Yong, "but there isn't much research into those that target the plants we depend upon."
Yong explains just how many other foodstuffs are affected by these plant diseases. Read the full story: "What Ants Can Teach Us About Agriculture."