Natures wonders: ants who are slave owners (Introduction)

by David Turell @, Sunday, March 03, 2019, 19:17 (199 days ago) @ David Turell

Raid another colony of different ants and steal larvae:

"Temnothorax americanus is a slavemaking ant found in northeastern America. These tiny social insects neither rear their offspring nor search for food themselves. Instead, they raid nests of another ant species, Temnothorax longispinosus, kidnap their larvae and pupae to bring these back to their own nest. Once these have reached adulthood, the abducted ants must feed the brood of the slavemaking species, search for food, feed the slavemakers, and even defend their nest. A colony of slavemakers, consisting of a queen and two to five workers, can keep 30 to 60 slaves. In a new study, biologists from Johannes Gutenberg University Mainz (JGU) examined the special relationship between the parasites and their host and made an exciting discovery: The ability of the host ants to defend themselves depends crucially on whether the raiding slavemakers come from an area with a successful or less successful parasite population. If the slavemakers come from a site where slavemakers are rare, the host ants react aggressively to the invaders. If, in contrast, the intruders come from an area where slavemakers are common, the hosts do not recognize them and, as a result, do not respond aggressively. The study also revealed that this difference in how they react is also reflected in how active the genes associated with aggression are in the brain of the ants.

"Similar to avian brood parasites such as cuckoos, T. americanus belongs to a class of parasites known as social parasites that do not directly harm the bodies of their hosts, but manipulate their social or brood care behavior instead. The social parasites and their hosts are engaged in a "co-evolutionary arms race": The parasites perfect the exploitation of their hosts, while the hosts continually develop better defensive strategies. When parasitic pressure is low, T. longispinosus reacts to an attack with coordinated combat, but, in sites where parasitism is more prevalent, its defense strategy shifts from fight to flight. It was the precise nature of this relationship, and the corresponding reactions, that Professor Susanne Foitzik's work group at the JGU Institute for Organismic and Molecular Evolution (iOME) investigated in the new study.


"Significantly, major changes in ant behavior can be triggered by individual genes. One particularly important gene is Vitellogenin-like A, which is very active in brood carers. If this gene is downregulated, the workers stop caring for the colony's offspring and spend more time caring for adult nestmates. The findings of the researchers from Mainz show that the gene Vitellogenin-like A influences the workers' sensitivity to brood odors. If the ants no longer sense the brood, they stop caring for them. These experiments show how the division of labor in social insect societies is regulated in that group members react in different ways to specific stimuli associated with distinct tasks in the ant society. (my bold)'

Comment: complete evidence for automatic behavior controlled by their genes.

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