Large Blue - Wild Connection

Everything in the natural world is connected; parasites and hosts, predator and prey and all the other symbiotic relationships to name just a few. Many of these connections are still unknown and certain types are extremely complex and rely on multiple different organisms.

Today I’m going to be talking about the Large Blue (Maculinea arion) and for those of you who do not know this is a species of European butterfly, which were found in the UK from 1795 till 1979. But it was then reintroduced in 1984 with a greater understanding on what it requires to be successful and became one of the UKs best reintroduction programs.

The problem the large blue faced is that through its multiple life stages it requires specific habitat and conditions which were decreasing in the UK. For instance they will only lay their eggs on wild thyme or marjoram flowers but in turn these plants require certain conditions. They are generally only found in grasslands which are well drained, acidic coastal or limestone based areas which are well grazed.  This generally means that these grasslands need to be well populated by species such as rabbits which will keep the grasses low so as not to out-compete the flowers whilst not damaging the flowers themselves which happens when larger domesticated animals such as cows are present. 

Once hatched the larva depend on a single species of ant (Myrmica sabuleti). It has long been know that ants were involved in the large blue’s life cycle but it wasn’t until the late 1970s that Jeremy Thomas uncovered the specific reliance. The large blue relies on these ants in a part parasitic part symbiotic relationship, as they are taken down into the ant’s colony where they feed on the grubs both dead and alive. It is thought that this process is both parasitic and symbiotic as although some potential ants are lost from the colony the larva also is helping to effectively clean the nest of dead individuals.  

Finally the larva will metamorphose into an adult and emerge from its subterranean existence then will climb onto some vegetation and proceed to expand its wings. From that point of the butterfly will rely on wildflowers nectar as a food source to provide them with sufficient energy to find a mate and contribute to the next generation.

The extinction of the large blue in 1979 was believed to be due to a number of reasons but it boiled down to two main reasons. The first of which was due to excessive uses of pesticides in the areas it can be found which killed the butterflies at each of their life stages. While the second reason was believed to be due to our lack of understanding of the species specific behaviour and so as we changed the grasslands through overgrazing and other activities to benefit humans the butterflies suffered. Luckily however since the successful reintroduction program the is believed to be a positive growth trend in the large blue UK populations.

So to summaries this one invertebrates influences and needs within the natural world it are; two types of plants to lay their eggs, grazing animals, ants and then flowers as an adult food source and if any of this critical components are lost from the chain the large blue will become extinct as it did in 1979.

You could almost class the large blue as an umbrella species! To find out more information on umbrella species check back next week.

Thanks for reading!

Check this video from Daan Varhoeven