Nesting biology of the arboreal fungus-growing ant Cyphomyrmex cornutus and behavioral interactions with the social-parasitic ant Megalomyrmex mondabora

Abstract

We describe the extraordinary nesting habits of the fungus-growing ant Cyphomyrmex cornutus (Formicidae, Myrmicinae, Attini) and the natural history of Megalomyrmex mondabora (Formicidae, Myrmicinae, Solenopsidini), a social parasite that inhabits nests of C. cornutus and other small attine ants. The study was carried out at two sites on the Atlantic slope of Costa Rica. The C. cornutus nest is an oblong mass of accreted soil, attached to or suspended from low vegetation in wet forest understory. Less than a fourth of the nest volume has chambers and is inhabited by C. cornutus; the remainder is a semi-solid mass of accreted soil often housing a variety of arthropods, including other unspecialized commensal ant species. Five C. cornutus colonies examined were parasitized by M. mondabora. Colonies of M. mondabora inhabited chambers very near those of the host. In laboratory observations, M. mondabora and C. cornutus workers interacted with little aggression despite the consumption of C. cornutus larvae and fungi by M. mondabora. During most interactions, C. cornutus workers responded submissively, whereas M. mondabora appeared indifferent or nonresponsive. Megalomyrmex mondabora parasitizes several other attine species (Cyphomyrmex costatus, Cyphomyrmex salvini, and Apterostigma goniodes), and it appears therefore a relatively unspecialized social parasite with broad attine hostassociation. The size of M. mondabora workers vary with host species, suggesting M. mondabora sensu lato comprises either cryptic species or the host environment affects worker size.

Chemically armed mercenary ants protect fungus-farming societies

“…Most details about the diversity and life history adaptations of these ants have been clarified only recently (11), and much of their biology remains to be discovered (SI Text: Study System and Tables S1 and S2). Free-living predatory Megalomyrmex are known to biosynthesize venom alkaloids that are used in defense (13,14) whereas the fungus-growing ant associates seem to aggressively dispense these venoms when they attack host colonies (15). Some of these parasites are obligate or facultative thief ants consuming brood and fungus gardens (15), whereas others are specialized agro-predators that move from one host colony to the other after usurping fungus gardens and killing or chasing away the resident ants (10).…”

Amazon Rainforest Ant-Fauna of Parque Estadual do Cristalino: Understory and Ground-Dwelling Ants

“…Four other genera were restricted to vegetation: Azteca, Myrmelachista, Nesomyrmex and Tapinoma. Species of these genera usually nest on plants (Longino, 2007;Nakano et al, 2013;Longino, 2004). Cephalotes was another genus with a greater number of arboreal species, with just C. atratus being collected in both strata.…”

“…Ants strongly influence several terrestrial communities due to their abundance and potential relationships with various biological groups. The interactions of ants can be positive or negative, ranging from interactions with microorganisms (Hanshew et al, 2014;Sanders et al, 2014), plants (Izzo & Vasconcelos, 2009;Vicente et al, 2012Vicente et al, , 2014Koch et al, 2015) and other invertebrates (Dáttilo et al, 2012a;Freitas & Rossi, 2015;Puker et al, 2015), even other ants (Adams et al, 2007;Sanhudo et al, 2008;Gallego-Ropero & Feitosa, 2014). Therefore, ants have been used as a model to understand the various ecological patterns and as valuable bio-indicators of environmental change or disturbance (Andersen et al, 2002;Bruna et al, 2014;Falcão et al, 2015).…”

Nest Biology and Demography of the Fungus-Growing Ant Cyphomyrmex lectus Forel (Myrmicinae; Attini) at a Disturbed Area Located in Rio Claro, SP, Brazil

“…With respect to the demographic observations, the colonies of C. lectus had an average worker number per colony smaller compared to two other Cyphomyrmex species studied, C. cornutus (Adams & Longino, 2007) and C. transversus (RamosLacau et al, 2012). Colonies of C. lectus presented a single dealate queen.…”

“…However, other Cyphomyrmex species (e.g. C. transversus and C. cornutus) present a highly distinctive nesting biology compared to C. lectus, C. strigatus and C. rimosus (Adams & Longino, 2007;Ramos-Lacau et al, 2012). For example, in Costa Rica, on Atlantic slopes, Adams Contrasting with another Cyphomyrmex species (rimosus group) described by Leal et al (2011), the fungus garden in C. lectus was well-defined (yeast-like fungi formed a sponge mass) and arranged at the bottom of the chambers.…”