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foliage - carver ants , which use leaf to raise a fungal crop to abide a colony of million , seem to have discovered farming long before humans germinate . They may also have beaten us to natural pesticides by a well-to-do margin .
Although it ’s not potential to assign a date to the ants ' latter discovery , the result of a new study suggest that fungus - work ant may have co - evolved with bacterium whose antibiotic compounds help them protect their crop . [ Infographic : The Life of an Ant ]
A worker leaf-cutter ant in a fungus garden. These gardens grow the crop that feeds the colony.
There are 230 specie of fungus - husbandry ant , all of which cultivate fungus for solid food . However , their fungal crop is often assail by a epenthetic fungus , calledEscovopsis . To foreclose infections , the ants have adopted especial defenses against the parasite , including fungus grooming , in which they run their mouthpart over their harvest and swosh up the parasite ’s spores , accord to senior researcher Cameron Currie , an evolutionary biologist and microbiologist at the University of Wisconsin in Madison .
A bacterial ally
As a doctoral student , Currie discovered leafage - cutting tool ants carry bacterium around with them , visible as fuzzy clean patches on their exoskeleton . later on , in 2005 , he and fellow worker discover the bacteria asPseudonocardia , which is part of a group , Actinobacteria , that isa rootage of human antibiotics . There was evidence that the bacterium helped the ants maintain their fungus gardens , leading the researchers to consider that ants had beat humans to some of our major innovations , Currie say .
" It was a bit of a joke at first , " he said .
In enquiry published Wednesday ( Nov. 24 ) in the daybook the Proceedings of the Royal Society B , Currie and his team notice that of the or so six type ofPseudonocardiabacteria , sure types are assort with certain metal money of ant and their agrarian systems . For illustration , among ant that elicit fungus on snub leaves , the vast bulk of thesymbiotic bacteriapresent belong to two close associate groups .
The researchers also tested how effective differentPseudonocardiastrains were in repress fungal growth , particularly that of the emmet ' nemesisEscovopsis . Here , they regain that the parasite was more susceptible to the antibiotic produced byPseudonocardiathan were other kingdom Fungi . They also noticed that strains ofPseudonocardiafound dwelling on ants were more effective against the leech than free - life straining .
A long history together
Currie estimates that ants have been farm fungus garden for up to 50 million year . Relatives of the parasitic fungus are know to attack other fungi , including relative of the fungal craw . This suggests that when ants domesticated the fungus , they in all probability acquired the pathogen as well , he said .
It ’s hard to put a date on when the pismire levy the bacterium to help , but this study evoke the bacteria have been associate with this organization for long period as well , he say .
In fact , some fungus - growing emmet housePseudonocardiawithin cavity in their workers ' exoskeletons , and may even feed them from specialized glands . On their spousal flying , queens carry a shot of the fungal crop in their mouth and the bacterium on their exoskeletons to their new colony . To have such a specialised partnership suggests a long period of evolution .
What ’s more , a art object of amber from the Dominican Republic offers a more - than-20 - million - year - old clue : Bacteria are visible on an ant trapped within it . It ’s not unclouded ; however , which character of bacteria is associated with the preserved ant , according to Currie .
Other organisms also seem to be need in this ant - fungus - bacteria scheme . Another type of bacterium transforms nitrogen into a useable form , effectively fertilizing the cultivated fungiin folio - cutter farm . Meanwhile , black barm appear throughout the farms , and inquiry has shown that , at least in one system , they eat thePseudonocardia , making it more difficult for the pismire to feed their harvest . [ See Live Leaf Cutters on the Ant - Cam ]
