Using chemo-taxonomy of host ants to help conserve the large blue butterfly

Abstract

The large blue butterfly (Phengaris arion) is an endangered Palaearctic species that was reintroduced into the British Isles after becoming extinct in 1979. The conservation of this butterfly in Britain is extremely important as it is a priority species under the UK Biodiversity Action Plan. P. arion larvae are highly specialised parasitizing the ant Myrmica sabuleti, but are also adopted into nests of other Myrmica species, particularly M. scabrinodis, where they are unable to survive. Therefore, it is critical for the success of any introduction programme to ensure that the correct host ant species is present. This poses a major challenge since Myrmica ants, especially M. sabuleti and M. scabrinodis, are morphologically extremely similar with the correct identification proving problematic even for the trained myrmecologist. Here we demonstrate that chemo-taxonomy can be used as a fast, cheap and accurate way to separate morphologically similar species. We found that using the simple presence or absence of just two species-specific compounds found on the ant’s cuticle we could easily, reliably and quickly separate M. sabuleti (5-methylpentacosane) from M. scabrinodis (3-methyltricosane) from samples taken from across Britain. This knowledge will help increase the success of future reintroduction programmes of P.arion by allowing non-specialists to ensure the correct host species is present prior to any introduction. To our knowledge, this is the first time that chemo-taxonomy has been applied specifically to aid the conservation of an endangered species.