Around 70% of all known animal species are insects and in the midst of what has been qualified as the ‘sixth extinction’ or 'biological annihilation', invertebrates are particularly endangered and mankind hasn't fully realised the consequences of it on its own future survival. All throughout the world, butterflies, which are known for their graceful flights, variety of colours and even for their remarkable migrations, are particularly in decline due to climate change and habitat loss.
Heliconius are a distinctive group of tropical butterflies known for their mimicry abilities and the diversity of their bright wing colour patterns, which warn predators of their toxicity. Ranging from South to North America, Heliconius have been studied by entomologists for centuries. They have helped scientists to understand biodiversity and how new species are formed. Here, in the Panamanian Jungle, scientists from the Smithsonian Tropical Research Institute (STRI) in Gamboa, have an ideal working environment, the Soberania National Park, to collect and study native Heliconius species.
The Smithsonian’s Museum of Natural History has a historic collection of around 3 million Lepidoptera (butterflies and moths) that are used for education and research purposes. However keeping up to date data records of butterfly populations is essential to help define their conservation status and to make an informed decision on the necessary protection measures. STRI’s Heliconius’ research lab, overseen by Owen McMillan, particularly focuses on the genetics of adaptation and speciation.
The Heliconius Stock Centre and Rearing Facility at STRI, aims at supporting scientific research, especially ecological and evolutionary genetics, through the captive breeding of Heliconius butterflies. The insectaries provide a home to a variety of species and races along with their passiflora host plants that they depend on. It is essential to understand the mechanisms behind each butterfly species’ evolution to understand their needs and threats, so they have a better chance at survival.
Moths and butterflies rely on plants all through their lives, from the moment they lay their eggs on specific plants so that the hatching caterpillars can immediately start feeding on their host, to foraging and feeding on nectar. Heliconius for instance get their highly distasteful quality from the poisonous passion-vine that the larva feeds on and are particular in that they eat pollen.
Heliconius species will reflect their distastefulness in their vivid coloured wings, which warns predators not to eat them. New discoveries in genetics have helped researchers learn more about the mechanisms behind it. In the past year, an international research team at STRI managed to knock-out a single gene, the WntA, in several species of butterflies, and manipulate the colours and placement of their wing spots and stripes. Thanks to ground-breaking science, they managed to create mutant specimens, like this one engineered by Carolina Concha, deriving from a Heliconius Erato Demophoon, helping them understand exuberant diversity of butterfly wing patterns in nature!
It is extremely important to understand the evolution of butterfly ‘species as characteristics such as their wing colouration and pattern are central to their survival. For Heliconius species it acts as both a warning to predators and a cue for mate recognition. Different species have evolved to mimic one another in order to share the cost of educating predators. In Heliconius, there have been several instances where important genes have been exchanged through hybridisation, which have helped create diversity and shape new species.
Here, Dr Chi-Yun Kuo, experiments with a decoy to capture the behaviour of Heliconius specimens on footage, and their possible hybridization. By combining behavioural essays and cutting-edge genetic techniques, his team seeks to uncover the genetics of mate preference and its role in the evolution of species.
Heliconius butterflies display a unique feeding behaviour and like any other butterfly they not only depends on the plants they feed on, but the plants also depend on the butterfly’s pollination services. Here, researcher Fletcher Young, uses artificial flowers, to train the butterflies to associate food with a specific shape. It is essential to understand what drives pollinators to act the way they do, mate the way they do, feed the way they do and play a specific ecological role in the food chain, to gather information that could potentially be used for their conservation.
Butterflies are extremely sensitive to changes in their habitat and even subtle climatic variations, which is why they are considered great indicators of environmental well-being. Deforestation and extensive use of pesticides are two of the greatest anthropogenic causes to their decline. The only way of supporting their numbers is through combined scientific research and conservation actions. As pollinators, they play a key role in supporting biodiversity of flora and fauna, to which humanity’s survival depends on.