Plants with ants

Nepenthes bicalcarata Ant-plant mutu­al­isms play key roles in the func­tion­ing of trop­ical eco­sys­tems, and are often import­ant com­pon­ents of trophic webs but the net bene­fits to each part­ner are rarely quantified:

A Carnivorous Plant Fed by Its Ant Symbiont: A Unique Multi-Faceted Nutritional Mutualism. (2012) PLoS ONE 7(5): e36179. doi:10.1371/journal.pone.0036179
Scarcity of essen­tial nutri­ents has led plants to evolve altern­at­ive nutri­tional strategies, such as myrme­co­trophy (ant-waste– derived nutri­tion) and car­ni­vory (inver­teb­rate pred­a­tion). The car­ni­vor­ous plant Nepenthes bic­al­carata grows in the Bornean peat­swamp forests and is believed to have a mutu­al­istic rela­tion­ship with its sym­bi­otic ant Camponotus schmitzi. However, the bene­fits provided by the ant have not been quan­ti­fied. We tested the hypo­thesis of a nutri­tional mutu­al­ism, using foliar iso­topic and reflect­ance ana­lyses and by com­par­ing fitness-related traits between ant-inhabited and unin­hab­ited plants. Plants inhab­ited by C. schmitzi pro­duced more leaves of greater area and nitro­gen con­tent than unoc­cu­pied plants. The ants were estim­ated to provide a 200% increase in foliar nitro­gen to adult plants. Inhabited plants also pro­duced more and lar­ger pitch­ers con­tain­ing higher prey bio­mass. C. schmitzi-occupied pitch­ers differed qual­it­at­ively in con­tain­ing C. schmitzi wastes and cap­tured large ants and fly­ing insects. Pitcher abor­tion rates were lower in inhab­ited plants partly because of herb­i­vore deterrence as herbivory-aborted buds decreased with ant occu­pa­tion rate. Lower abor­tion was also attrib­uted to ant nutri­tional ser­vice. The ants had higher d15N val­ues than any tested prey, and foliar d15N increased with ant occu­pa­tion rate, con­firm­ing their pred­at­ory beha­viour and demon­strat­ing their dir­ect con­tri­bu­tion to the plant-recycled N. We estim­ated that N. bic­al­carata derives on aver­age 42% of its foliar N from C. schmitzi wastes, (76% in highly-occupied plants). According to the Structure Independent Pigment Index, plants without C. schmitzi were nutri­ent stressed com­pared to both occu­pied plants, and pitcher-lacking plants. This attests to the physiolo­gical cost of pitcher pro­duc­tion and poor nutri­ent assim­il­a­tion in the absence of the sym­biont. Hence C. schmitzi con­trib­utes cru­cially to the nutri­tion of N. bic­al­carata, via pro­tec­tion of assim­il­at­ory organs, enhance­ment of prey cap­ture, and myrme­co­trophy. This com­bin­a­tion of car­ni­vory and myrme­co­trophy rep­res­ents an out­stand­ing strategy of nutri­ent sequestration.


Ann Bot is a gestalt entity who works in the office for the Annals of Botany.

1 Response

  1. Mary W says:

    That’s a great story, and the most amaz­ing photo of a car­ni­vor­ous plant — love the “fangs”!