Dispersal of Attaphila fungicola, a symbiotic cockroach of leaf-cutter ants

Abstract

© 2017, International Union for the Study of Social Insects (IUSSI). The myrmecophile cockroach Attaphila fungicola lives in the nests of leaf-cutter ants (Atta texana and A. cephalotes) and uses the female winged reproductives (i.e., female alates) of its host as vectors for the first phase of its dispersal. It is unknown whether A. fungicola remain with vectoring A. texana females after mating flights and throughout A. texana nest founding and subsequent colony development, or if the symbiotic cockroaches disperse to established A. texana colonies, either on their own or while still attached to vectoring A. texana females. We captured A. fungicola attached to A. texana female alates as they prepared for mating flights and measured their survivorship in artificial brood chambers with de-alate, recently mated A. texana queens and their incipient gardens, and in a non-natal established fungal garden tended by A. texana workers. After 13 days, 100% of A. fungicola had died in brood chambers with queens, while 100% of A. fungicola remained alive in the fungal garden chamber. We tested the feasibility of alternative modes of dispersal to established colonies by placing A. fungicola attached and unattached to vectoring female alates in the proximity of an established A. texana colony directly after a mating flight, and recorded whether A. fungicola entered the non-natal nest. A significantly higher proportion of A. fungicola attached to vectoring alates entered the nest compared to unattached A. fungicola. We also placed A. fungicola attached to vectoring alates in a foraging chamber of a laboratory colony to determine if, once in the nest, A. fungicola could navigate to the fungal garden chamber; 100% of A. fungicola detached from their vectoring alates and entered the fungal garden chamber. We tested alate preference of A. fungicola by placing A. fungicola separately in containers with one A. texana female alate and one male alate; after 2 h, 71% of A. fungicola were attached to female alates and 0% to male alates. Finally, we report the first record of a male A. fungicola collected during a mating flight of A. texana. These observations accumulated from field and laboratory studies suggest that A. fungicola vectored by A. texana female alates may not remain with foundresses, but instead disperse between established colonies through one or more alternative mechanisms. This study helps elucidate a tripartite ant-fungus-cockroach interaction, and provides a foundation for future research on Attaphila dispersal and reproductive biology.