How butterfly larvae cheat ants into feeding them while letting their own brood starve

January 4th, 2008 - 1:48 pm ICT by admin  

Washington, January 4 (ANI): Caterpillars of large blue butterflies change their smell to dupe ant workers into believing them to be one of their own larvae, say researchers.

Investigators at the Centre for Social Evolution (CSE), Copenhagen University, say that their study shows that there is an ongoing co-evolutionary arms race in smell similarity between cheaters and their victims.

David Nash, Jacobus Boomsma and their colleagues studied large blue butterflies of the genus Maculinea, commonly known as the Alcon Blue, whose larvae are adopted by ant colonies and deceive the ants into feeding them while letting their own brood starve.

The researchers observed that superb chemical mimicry manipulates the ants into neglecting their own brood to care almost exclusively for their caterpillar parasites.

They also found that the ant hosts could evolve resistance against this exploitation by changing how they smell.

However, this only works when the host ants that live close to the initial foodplant of the caterpillars, the rare marsh gentian Gentiana pneumonanthe, do not interbreed with ants from neighbouring sites where the gentian does not grow.

Ant colonies are not parasitized in sites without the foodplant, which is why they do not evolve resistance, say the researchers.

They add that any resistance evolved in areas with butterflies is not effectively passed on to future generations because it gets diluted by the flow of non-resistant genes from the uninfected areas.

The research team has shown that the two red ant species of the genus Myrmica, host for the Alcon blue in Denmark, differed dramatically in their degree of gene-flow among neighbouring sites, even though they lived in the same gentian patches.

In line with evolutionary theory, they showed that selection for resistance only works when the ant queens mate locally with males from colonies that have likewise suffered from butterfly parasitism.

The researchers believe that their findings may give important insights into the fundamentals of evolutionary biology.

They revealed that the research was carried out in collaboration with British chemists, specialists on the study of chemical profiles on the surface of insects.

The findings have been published in the journal Science. (ANI)

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