Agro-predation by Megalomyrmex ants on Mycetophylax fungusgrowing ants.

Abstract

Fungus-growing ants are a remarkable taxon of New World ants that engage in a mutualistic symbiosis with basidiomycete fungi. Their fungus-gardens are valuable resources and are exploited in countless ways by parasites and other beneficiaries outside of the ant-fungi mutualism. Here, for the first time, we report on the agro-predatory behavior of the ant Megalomyrmex incisus on Mycetophylax conformis and Mycetophylax morschi fungus-growers from sand dunes near Ilhe´us, Brazil. Me. incisus workers raided colonies of My. conformis and My. morschi and aggressively antennated, pulled, bit, and stung the fungus-growers, which played dead or retreated on the fungus. Me.incisus quickly usurped the fungusgarden and expelled all Mycetophylax workers. The usurpation closely resembled that described for raids of Me. wettereri on Cyphomyrmex longiscapus, in that the fungus-growers remained passive and avoided confrontation. This passive behavior suggests that Me. incisus uses chemical weapons that facilitate the exploitation of the host colony resources.