The Rhopalocera and selected Macroheterocera (order: ‘Lepidoptera’) of the Maltese islands : an awareness tool for conservation

Abstract

The rapid economic growth and human development following the end of World War II has had a profound impact on the butterfly fauna of the Maltese islands. Habitat destruction, degradation, and fragmentation, together with extensive urbanisation, intensive agricultural development, and the introduction of invasive alien species, accidental or otherwise, have all contributed towards the decline of many local butterfly populations. In some cases, certain species that were once a fairly common sight have today become so rare that it is believed these butterflies face imminent extinction from the islands unless immediate action is taken. In order to understand the main drivers behind these changes, the study aimed to compare historical collection data with more recent monitoring records so as to evaluate the changes in butterfly distribution over time. Several entomological collections were viewed to retrieve and map the historical distribution data of the Rhopalocera and selected macro-Heterocera (in this case the Sphingidae, or Hawkmoth family, and the Catocalinae, or Underwing sub-family) of Malta. Butterfly monitoring programmes were also carried out in 21 different sites across the island, using transect walks and checklist surveys to assess the presence or absence of butterfly species in the area. These records outline various trends in the evolution of butterfly population and species dynamics. Heavily cultivated agricultural areas and large public gardens that were once regarded as butterfly hot-spots have experienced a severe loss in species due to the excessive use of pesticides, whilst other areas that have been subject to significant land use change or urbanisation have also experienced a decline in species. Comparatively, more stable areas such as less disturbed valley systems appear to have retained relatively healthy butterfly populations. Several management strategies are also recommended, with the intention of improving butterfly conservation in the Maltese Islands and restoring butterfly populations to stable and healthy levels.