Myrmeconema neotropicum is a nematode parasite that infects ants. The eggs can also use birds for transportation (a paratenic host). Eggs present in bird feces are fed by ants to their developing brood (1). As the infected ant larvae grow into adults, the worms also grow and develop into adults within the ant’s gaster (hindmost region of the abdomen). The worms mate and once the females are full of mature eggs, the gaster of the ant turns red (2). Infected ants are slightly smaller, heavier, more sluggish, clumsier, and less aggressive than uninfected ants (2). As the infected ants walk, they hold their gaster in an elevated position, which, combined with their red colour, can cause birds to mistake them for berries (1). When an infected ant gets eaten by a bird, the eggs within the females are released and passed with the bird feces (1).
The only known ant host for M. neotropicum is Cephalotes atratus, though other Cephalotes spp. may also be able to be infected (2). Consequently, M. neotropicum has only been found in the tropical regions of South America (2). Infection of the ants has been found to cause their gasters to be bigger, but have lower metabolic rates, despite the eggs entering a quiet state and not consuming much of the host’s energy (3). Rather, most of the energy taken from the host by the parasite is thought to happen while the ant is a larva and the worms are still developing (3).
1. 10.1086/528968
2. 10.1007/s11230-007-9125-3
3. 10.1645/GE-2735.1
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Dr. Chenhua Li (Lead, Ideas), Dr. Þórey Jónsdóttir (Illustrator, Ideas), Stephen Pollo (Writer, Researcher), Yuanzhe Wang (Digital Consultant).