Assessing the conservation status of selected insects in the Maltese Islands

Abstract

The main aim of this dissertation is to present an evaluation of the conservation status of selected groups of insects of the Maltese fauna, including a reassessment of selected species listed in Schembri and Sultana (1989). Species were evaluated using IUCN criteria based on data from literature published over the last 30 years. Selected species within 48 selected families from Coleoptera, Diptera, and Lepidoptera were considered on the basis of the information available. The conservation status using IUCN categories as well as notes are provided for each species that was (re)evaluated. Overall, a total of 381 species were successfully (re)assessed, including 95 species from Schembri and Sultana (1989). The overall percentages of IUCN categories that were evaluated is as follows: ‘Least Concern’ – 6.3%, ‘Near Threatened’ – 5.5 %, ‘Vulnerable’ – 13.6%, ‘Endangered’ – 27.3%, ‘Critically Endangered’ – 15.5%, ‘Possibly Extinct’ – 13.6%, ‘Data Deficient’ – 17.6%, and ‘Not Applicable’ 0.3%. There was a significant change in the IUCN conservation status of selected species that were mentioned in Schembri and Sultana (1989), with 59% of species evaluated being in a threatened or near threatened category, an increase from 1% to 11% of species classified as ‘Possibly Extinct’, and from 0% to 3% in the ‘Least Concern’ and ‘Near Threatened’ categories; and a decrease in the ‘Vulnerable’ (from 21% to 18%) and the ‘Endangered’ (from 30% to 24%) categories. This may be due to using a more objective approach when evaluating the species with the standardised IUCN criteria, rather than the previous subjective approach. When comparing distribution type (endemic vs nonendemic), no significant difference was found on extinction risk. This was probably due to the fact that even non-endemic species are frequently threatened at the local scale because of their small extent of occurrence and area of occupancy at the national scale, in turn largely a consequence of the small size of the islands. Moreover, the last recorded locations of ‘Critically Endangered’ and ‘Possibly Extinct’ species, as well as all the distribution data for threatened species, were visualised on QGIS maps, which display clustering in locations such as Buskett, Marsa, Salina, Mġarr, Rabat, Dingli, Marsaskala, Marsaxlokk, Girgenti, Mellieħa, Għar Lapsi in Malta, and Ramla, Marsalforn, Victoria and Xlendi in Gozo. These locations include habitats such as sand dunes, salt marshes, and freshwater pools, and are considered vulnerable due to human impact, climate change, and habitat loss. Therefore, these locations should be of conservation priority. In conclusion, long-term monitoring as well as further research into the ecology of the species evaluated, as well as assessment of both direct and indirect impacts that are contributing to insect population decline, is recommended in order to develop better conservation strategies for the preservation of the Maltese insect fauna.