Internal bacterial makeup of three major life stages of butterfly sequenced

A research team has sequenced the internal bacterial makeup of the three major life stages of a butterfly species.

The team, led by CU-Boulder doctoral student Tobin Hammer, used powerful DNA sequencing methods to characterize bacterial communities inhabiting caterpillars, pupae and adults of Heliconius erato, commonly known as the red postman butterfly.

The red postman is an abundant tropical butterfly found in Central and South America.

The results showed the internal bacterial diversity of the red postman was halved when it morphed from the caterpillar to the chrysalis, or pupal stage, then doubled after the pupae turned into active adult butterflies.

The butterflies were collected at a field site in Gamboa, Panama, and data analysis was done at CU-Boulder.

The main motivation for choosing the red postman for study is that its genus is the only one that feeds on pollen, a rich source of amino acids, Hammer said. Most butterflies feed on nectar-essentially sugar water-leading to abbreviated lifespans lasting only days or weeks.

But the red postman apparently has found a way to digest and then extract nutrients from pollen grains, likely expanding its lifespan by several months.

Also, it appears that red postman caterpillars, which acquire nutrients from leaves they consume, are able to divert more resources toward making compounds that are toxic to some predators, Hammer said. Adult red postman butterflies are filled with the same compounds, which release cyanide when the butterfly is eaten.

The subject has been published online in the journal PLOS ONE.