Newsletter March 2018
Welcome to the first newsletter of the Mid Atlantic Island Invertebrate Specialist Group of 2018. We have some really interesting articles, including new data on Sawflies and Horntails of Madeira and the conservation of the La Palma stick grasshopper on the Canaries. We will be putting the newsletter up on the website and also thank you to everyone who provided a photo and biog for the websi.
Vicky and Paulo
Invasive Argentine ants attack bird nestlings in Desertas Islands (Mário Boieiro)
On Madeira during the 19th century the Argentine ant (Linepithema humile) was introduced and is now considered a severe urban pest being responsible for significant economic impacts, particularly in agriculture. However, its impacts on the native biodiversity in natural areas of the archipelago remains poorly known.
Recently, it was found that this invasive species can prey upon bird nestlings from different species, like the Atlantic canary (Serinus canaria), the common tern (Sterna hirundo), the Bulwers petrel (Bulweria bulweri) and the yellow-legged gull (Larus michahellis), in Desertas Islands (Boieiro et al. 2018). This finding is particularly worrisome because some threatened bird species use these oceanic islands as important breeding sites. Furthermore, this finding highlights the need for monitoring Argentine ant impact on Desertas native biodiversity since rare endemic terrestrial invertebrates are also known to be preyed upon by this invasive species.
Boieiro, M., Catry, P., Jardim, C.S., Menezes, D., Silva, I., Coelho, N., Opliveira, P., Gatt, M.C., Pedro, P. & Granadeiro, J.P. (2018) Invasive Argentine ants prey on Bulwers petrels nestlings on the Desertas Islands (Madeira) but do not depress seabird breeding success. Journal for Nature Conservation, Online early.
Sawflies and horntails of Madeira Archipelago (Antonio Aguiar)
This group of interesting phytophagous Hymenoptera are poorly studied on these islands and previously only four species were known. As the result of recent surveys this number has now tripled to 12 species. Most of them are introduced species (as is common nowadays) but there are also some native and probable native species shared with the Azores. The most interesting is a species that feeds on the Macaronesian endemic willow Salix canariensis in both Madeira and Tenerife in the Canarian Islands, this species was unfortunately not identified due to the difficulty in breeding the adults from collected larvae.
The Symphyta (sawflies and horntails) are rich in endemic species, but to the contrary of the 12 recorded 3 may be probable native species and only one of them a probable Macaronesian endemic (Canary Islands and Madeira) breeding on Salix canariensis. So most are introduced non-native species; however, from conservation point of view the potential negative impacts remain with those that could be considered invasive species. It seems that only the woodwasp Sirex noctilio is considered an invasive species and although it attacks only species of pines and other Pinaceae; pines are not endemic in Madeira but have economic and landscape conservation importance.
The following are cited as new for the Island of Madeira: Aneugmenus coronatus, Cladius brullei, C. pectinicornis, Pristiphora abbreviata, Strongylogaster multifasciata and Urocerus gigas. The following species are also cited as possible new records but need further confirmation: Endelomyia aethiops and a species of Euura sp., which is a probable native of central Macaronesia. Also added as new records were the parasitoids of siricid wasps: Ibalia leucospoides and Rhyssa persuasoria.
Research projects for conservation of La Palma stick grasshopper (David Hernández, Heriberto López, and Pedro Oromí)
The grasshopper family Pamphagidae is represented in the Canary Islands by the endemic genus Acrostira in the central and western islands, and Purpuraria in the eastern ones. Acrostira includes four single-island endemics, two of them occurring in very restricted areas with greatly reduced populations: A. tenerifae in Tenerife and A. euphorbiae in La Palma. The latter is included in the Canary and Spanish official Red-lists and the IUCN Red List of Threatened Species as critically endangered. It is particularly imperiled due to tourist development pressures to build a golf-course and resorts in its distribution range, and by repeated wildfires in recent decades. In particular, the major 2009 fire devastated the vegetation of a third of this area.
This grasshopper was considered to feed mostly on dendroid Euphorbia shrubs, which were highly damaged during the fire. Two research projects, funded by the Mohamed Bin Zayed Species Conservation Fund from Abu Dhabi and the Cajacanarias Foundation from Tenerife, have provided the opportunity to find out if Acrostira euphorbiae can survive by feeding on other plant species, and to check how much its populations were affected by the fire. A study of their diet was performed, analysing the faeces of individuals collected in the wild and comparing the contents with pre-identified plant epithelial tissues, and experimental studies of their food preferences were developed in the lab with captive individuals.
The results indicate that these endemic grasshoppers are not monophagous as previously believed. Though Euphorbia lamarcki was the most consumed plant species, they do not consume it exclusively, since they also feed on two other plant species present in their habitat: Retama rhodorhizoides and Pinus canariensis. At least in captivity conditions, we have found they usually prefer E. lamarckii, then R. rhodorhizoides and finally P. canariensis. Therefore, it seems that E. lamarckii is still essential to maintain the populations of this endemic grasshopper, even though it consumes other plant species in its natural area. Wildfires are still one of the main threats to this species; although they have not led to its extinction they cause considerable numerical impact on its population.
Progress on Securing the Future of St Helenas Endemic Invertebrates (Amy-Jayne Dutton)
This Darwin Plus invertebrate funded project is continuing at full speed and will provide greater information on terrestrial invertebrate numbers, diversity and variation across the year on St Helena. Until this project, invertebrate research has been limited to short periods of time, often at the same time of year. Twenty-four malaise traps were placed across St Helena, in habitat varying from semi-desert to cloud forest, and opened every 4 weeks for 10 months. Information on habitats, including conservation efforts, and weather, will also be looked at in conjunction with the invertebrate data gathered to address the following research questions:
Determine the impact of invasive predatory species on native invertebrate species and their habitats
Determine the effect of seasonality on invertebrates
Determine the effect of conservation efforts for habitats on invertebrates
Determine invertebrate diversity and abundance differences between natural, restored and non-native habitats
Assess shifts in distribution of invertebrates attributable to global warming
A national collection of the invertebrates found on the island is being compiled, with the aim being that 100 % of species represented. To date we have 1408 specimens from 373 species representing 30.3 % of terrestrial invertebrate species. Staff are also getting out in the field to continue targeted species collections, species observations and habitat assessment. Work includes photographing jumping spiders, as they lose their striking colouration in alcohol, and observations of the Mole Spider (Lycosidae), believed to be new to science.
In February 2018 the team were joined by Coleoptera expert Howard Mendel from the Natural History Museum in London, and Jo Hatton from the Horniman Museum in London, for 3 weeks of intensive field work. Areas were targeted where rare species might be found. Howard has taken specimens back for detailed investigation and believes he has 8 species to be described from these samples. Shortly Timm Karisch a moth expert will return to the island and will focus investigations on the endemic moths, particularly the numerous Opogona species. As well as collections of adult moths for identification and genetics work, in addition investigations will be made into the larvae and their associated food plants and habitat requirements.
The project finishes at the end of June and the results of this will be invaluable in moving invertebrate research forward on St Helena. This project will leave a legacy of better understanding of invertebrate presence and distribution, staff with identification skills and experience and a greater knowledge and awareness of invertebrates and their requirements.
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