These Special Butterflies Are Nurtured by Ants

Researchers at the University of Debrecen have completed the most comprehensive analysis to date on the host use by brood parasitic butterflies. It took ten years of work to compile the report in the form of a database containing of the efforts and findings of as many as 40 scientists.

The result can significantly contribute to the understanding of the lifestyle and behavior of other parasites, too.

In our country, the most widely recognized representatives of brood parasites are the cuckoos, who smuggle their eggs into the nest of other birds; however, they are not the only species that let others take care of bringing up their offspring. In fact, the strategy of brood parasitism appears among birds, fish and even some insects. It is the latter of these that the so-called Maculinea butterflies, brood parasites who have their descendants “brought up” by ants, belong to. Research had been launched at the University of Debrecen about them as early as 2002 in the framework of the so-called MacMan project, with the participation of experts from Britain, France, Denmark and Poland. Back then, the focus was on issues such as the genetics, habitat and behavior of these butterflies, with special attention to how they adopt to the local ant species in their respective environments.

“These species of special lifestyle play the part of indicators in the exploitation of hosts, since they can be present in a specific area only if they find both host plants and host ants. The caterpillars initially feed on the developing seeds of specific host plants, following which they drop on the ground and mimic an ant queen or ant grubs by emitting olfactory and sound impulses. Thus, they wait to be discovered, and then picked up and adopted by ant workers to carry them inside their nests. Ultimately, this strategy seems to work only for 1 or 2 percent of the caterpillars. In addition, a lot depends on what kind of ant host the individual caterpillars manage to find. The peculiar quality of the brood parasitism of these butterflies comes from the fact that they need to deceive not just one or a few ants. They must outwit the defense mechanism of the super-organism of an entire ant colony (which is why we call them social parasites),” said András Tartally, an Assistant Professor at Debreceni Egyetem Természettudományi és Technológiai Kar Evolúciós Állattani és Humánbiológiai Tanszék [Department of Evolutionary Zoology and Human Biology of the Faculty of Science and Technology of the University of Debrecen] and the first author of the recently published article.

During the course of their work, which has spanned ten years, the researchers mapped up where in Europe the butterflies use what kind of ants for their stunts. For the comprehensive database, more than 140 articles of 40 authors have been used, in which the collected data has been unified according to sites and habitats.

“The primary objective has been to complete the most comprehensive analysis available in a geographic mosaic on the exploitation of hosts by brood parasitic butterflies. Our findings and the final results of our research may serve as a point of departure for the study of other brood parasitic species as well. In addition, they may come in handy for experts from the aspect of protecting the mosaics of populations, in which the butterflies are present as a so-called umbrella species. Their presence is an indicator for the environmental specialists that both the butterflies and the ant hosts treat the habitat properly from the aspect of the host plants,” said András Tartally, whose research has been supported through scholarship grants from the Marie Curie-, Bolyai, and Bolyai+ organizations in addition to the MacMan project mentioned above.

This comprehensive report in the form of an article was published in the periodical Philosophical Transactions of The Royal Society B and is freely available here, in the electronic version of the leading forum for sharing findings in the field of evolutionary biology.
 
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