Assessment Rationale:

Simulium azorense is an endemic species of the Azores (Azores, Portugal), having been recorded from Flores, Faial, S. Jorge, Terceira, S. Miguel and St. Maria (Borges et al. 2010). This species is present in areas of native (and exotic) vegetation and in highly disturbed areas. From the current data available, this species has a relatively large extent of occurrence (EOO = 37,556 km2) but limited area of occupancy (AOO = 292 km2). This species needs permanent water sources, and therefore continuing habitat decline caused by changes to the natural local hydrology, diversion of streams for agricultural or other uses, or contamination by domestic runoff and pesticides can greatly affect this species. Indeed, current intensive pasture management in Azores is increasing freshwater pollution by nitrates. Habitat declines as a consequence of climate change and increased droughts (Ferreira et al., 2016) will also affect this species. A habitat management plan is needed, while degraded habitats and streams could also be restored and measures concerning water management and conservation, including formal education, public awareness and legislation, should be enacted. Additionally, a strategy needs to be developed to address the future threat by climate change. Given that the AOO of the species is relatively small, on the global scale, it is possible that the species could potentially qualify as threatened under criterion B2. However, the overall number of locations is likely to be >10, and so the species is assessed as Near Threatened.

Geographic Range:

Simulium azorense is an Azorean-endemic fly species described from the islands of Flores, Faial, S. Jorge, Terceira, S. Miguel and St. Maria (Azores, Portugal) (Borges et al. 2010), and it is possibly also present in Corvo and Graciosa (Crosskey 1986). It is known from habitats with streams and other sources of running water. Based on the historical data and more recent records, the Extent of Occurrence (EOO) is 37,556 km² and the minimum Area of Occupancy (AOO) is 292 km².

Population:

Simulium azorense is an Azorean-endemic fly species described from the islands of Flores, Faial, S. Jorge, Terceira, S. Miguel and St. Maria (Azores, Portugal) (Borges et al. 2010), and it is possibly also present in Corvo and Graciosa (Crosskey 1986). It is known from habitats with streams and other sources of running water. Based on the historical data and more recent records, the Extent of Occurrence (EOO) is 37,556 km² and the minimum Area of Occupancy (AOO) is 292 km².

Habitat and Ecology

All Simuliidae larvae are aquatic, developing in running water habitats of all types, from swift currents to barely moving waters. Larvae attach to various submerged objects in their habitat. Most larvae are filter feeders while others feed by grazing on organic debris around their attachment sites (McAlpine et al. 1981). Adult simuliids of both sexes feed on nectar as a food source, while females of most species feed on blood, some feeding exclusively on birds or mammals. Simuliid females are among the most serious insect pests of man and other warm blooded animals, being vectors of parasitic disease organisms (mainly filarial nematodes) (McAlpine et al. 1981). Simulium azorense larvae require running water, this species being present mainly in the vicinity of streams and other bodies of water. This species is likely present in all the islands of the archipelago, with the exception of Pico (that does not have streams) (Crosskey 1986), and it has potentially disappeared from Faial, after the earthquakes of 1957/1958 altered the local hydrology (Crosskey 1986).

Major Threat(s):

Despite an incomplete knowledge regarding the threats affecting this species, black flies need permanent water sources to complete their life-cycle, and changes to the natural hydrology, diversion of streams for agricultural or other uses, or contamination by pollution and pesticides can greatly affect this species, as confirmed by its apparent disappearance from Faial after the 1957/1958 earthquakes, which changed the local hydrology (Crosskey 1986). Indeed, current intensive pasture management in Azores is increasing freshwater pollution by nitrates. Habitat declines as a consequence of climate change and increased droughts (Ferreira et al. 2016) will also affect this species.

Conservation Actions

The species is not protected by regional law. It has been collected in some regionally protected areas, but also in degraded areas. A habitat management plan is needed and one is anticipated to be developed during the coming years. Degraded habitats and streams could also be restored and measures concerning water management and conservation, including formal education, public awareness and legislation, should be enacted. Additionally, a strategy needs to be developed to address the future threat from climate change; while further research is needed into this species' population, distribution, threats, ecology and life history.