Beware of the freeloader! The Blue Alcon Butterfly

The caterpillars of the Blue Alcon Butterfly (Maculinea alcon) have the ability to mimic ants smell and sound so they can be a freeloaders in the nest before developing into butterflies.

Young Maculinea  alcon caterpillar being carried to the nest
by a worker ant. (Source: Nature. Image by Nash)

An M. alcon caterpillar starts life off in a relatively standard way by feeding on flowers of its host plants however, after three to four weeks it drops from the plant to the ground. As a result of the caterpillar’s ability to secrete hydrocarbons that closely mimic the smell of red ant (Myrmica) larvae, it is taken back to the nest by worker ants and fed and cared for as if one of their own. This approach is commonly referred to as ‘cuckoo’ behaviour (Thomas & Settele 2004, Als et al. 2004, Mouquet et al. 2005, Arnaldo et al. 2011).

While in the ant nest, it continues to mimic the smell of the larvae and also makes sounds resembling the noises the ant larvae make to beg for food. In some cases, the caterpillar even mimics the sound of a queen and receives an even higher level of care (Cobb 2009). After continued care and feeding from the ants it develops its chrysalis and later hatches and makes its way out of the nest.

Unlike the ‘cuckoo’ behaviour of M. alcon, other species such as M. arion, M. teleius, M. nausithous and M. arionides take a predacious approach. While still entering the nests by secreting an odour mimicking ant larvae and causing ants to think they are their own, these species often do not stay to be cared for by the ants. Instead they retreat to ‘safer’ areas in the nest and return periodically to feed on ant larvae (Thomas & Settele 2004).

Studies have found cuckoo feeding behaviour is present in M. alcon, M. rebeli and also a more distant relative from the Phengaris genus. Thomas and Elmes (1998) and Als et. al. (2004) state that the cuckoo varieties in Maculinea and Phengaris definitely evolved from a common ancestor and speculate that this ancestor was predacious. If this is correct, this is a demonstration of convergent evolution of these species.

References

Als, TD, Vila, R, Kandul, KP, Nash, DR, Yen, S, Hsu, Y, Mignault, AA, Boomsma, JJ & Pierce, NE 2004, 'The evolution of alternate parasitic life histories in large blue butterflies', Nature, vol 432, no. 7015, pp. 386-390.

Arnaldo, PS, Wynhoff, I, Soares, P, Rodrigues, M, Aranha, J, Csősz, S, Maravalhas, E & Tartally, A 2011, 'Maculinea alcon exploits Myrmica aloba in Portugal: unusual host ant species of a myrmecophilous butterfly in a peripheral region', Journal of Insect Conservation, vol 15, no. 3, pp. 465-467.

Cobb, M 2009, 'Caterpillars make noises like ants', The Journal of Experimental Biology, vol 212, no. 12, p. v.

Mouquet, N, Belrose, V, Thomas, JA, Elmes, GW, Clarke, RT & Hochberg, ME 2005, 'Conserving Community Modules: A Case Study of the Endangered Lycaenid Butterfly Maculinea alcon', Ecology, vol 86, no. 12, pp. 3160-3171.

Nash DR, n.d. I'll take this one home, photograph, viewed 10 March 2014, <http://www.nature.com/news/2008/080103/full/news.2007.405.html>.

Thomas, JA & Elmes, GW 1998, 'Higher productivity at the cost of increased host-specificity when Maculinea butterfly larvae exploit ant colonies through trophallaxis rather than by predation', Ecological Entomology, vol 23, no. 4, pp. 457–464.

Thomas, JA & Settele, J 2004, 'Butterfly mimics of ants', Nature, vol 432, no. 7015, pp. 283-284.

Ugelvig, LV, Vila, R, Pierce, NE & Nash, DR 2011, 'A phylogenetic revision of the Glaucopsyche section (Lepidoptera: Lycaenidae), with special focus on the Phengaris–Maculinea clade', Molecular Phylogenetics and Evolution, vol 61, no. 1, pp. 237–243.