Virgílio Vieira

Ranking protected areas in the Azores using standardised sampling of soil epigean arthropods

Nineteen areas in seven of the nine Azorean islands were evaluated for species diversity and rarity based on soil epigean arthropods. Fifteen out of the 19 study areas are managed as Natural Forest Reserves and the remaining four were included due to their importance as indigenous forest cover. Four of the 19 areas are not included in the European Conservation network, NATURA 2000. Two sampling replicates were run per study area, and a total of 191 species were collected; 43 of those species (23%) are endemic to the archipelago and 12 have yet to be described. To produce an unbiased multiple-criteria index (importance value for conservation, IV-C) incorporating diversity and rarity based indices, an iterative partial multiple regression analysis was performed. In addition, an irreplaceability index and the complementarity method (using both optimisation and heuristic methods) were used for priority-reserves analyses. It was concluded that at least one well-managed reserve per island is absolutely necessary to have a good fraction of the endemic arthropods preserved. We found that for presence/absence data the suboptimal complementarity algorithm provides solutions as good as the optimal algorithm. For abundance data, optimal solutions indicate that most reserves are needed if we want that at least 50% of endemic arthropod populations are represented in a minimum set of reserves. Consistently, two of the four areas not included in the NATURA 2000 framework were considered of high priority, indicating that vascular plants and bird species used to determine NATURA 2000 sites are not good surrogates of arthropod diversity in the Azores. The most irreplaceable reserves are those located in older islands, which indicates that geological history plays an important role in explaining faunal diversity of arthropods in the Azores. Based both on the uniqueness of species composition and high species richness, conservation efforts should be focused on the unmanaged Pico Alto region in the archipelago’s oldest island, Santa Maria.

Sampling Plans for Pseudaletia unipuncta (Lepidoptera: Noctuidae) Larvae in Azorean Pastures

Abstract Pseudaletia unipuncta (Haworth) is a pest in Azorean pastures that causes up to 8% yield loss mainly during summer and early autumn. The objective of this research was to develop robust sampling plans based on larval spatial distribution. The number of larvae in three 60-m2 plots on S. Miguel Island (Azores) was determined. Plots of 0.25 m2 were the most accurate unit for estimating the population size. The relationship between mean and variance fitted both Taylor’s power law and Iwao’s patchiness regression model. Relationships to determine optimum sample sizes for fixed levels of precision based on both models were developed, but demanded a heavy sampling cost for the usual precision values (0.1–0.25). To reduce sampling effort, two sequential sampling plans were developed and compared, one based on Taylor’s parameters and the other based on Iwao’s parameters. For a precision of 0.25, Taylor’s sequential sampling plan led to an average 76% reduction of the sampling effort compared with sample sizes estimated for fixed levels of precision. Simulations of Iwao’s sequential sampling plan applied to larval counts correctly predicted a “treat” or “not-treat” decision for 91% of the cases. However, this plan estimated field densities with a lower degree of precision than Taylor’s plan and required a considerable increase in sampling effort for larval densities close to the critical mean. Use of Taylor’s sequential sampling plan should provide effective management of P. unipuncta in grass pastures and minimize sampling time and cost.

Larval aquatic and terrestrial mites infesting parthenogenetic Ischnura hastata (Odonata: Coenagrionidae) from the Azores islands

We report here the prevalence of parasitism by water mites (Arrenurus sp.) and terrestrial mites (Leptus killingtoni) on parthenogenetic Ischnura hastata (Odonata: Coenagrionidae) from the Azores islands. Leptus killingtoni was only found on the island of Pico, and the prevalence of infestation was highly variable among the different ponds studied, ranging from 0 to 41%. Leptus killingtoni was observed on three of the four odonate species from the archipelago: I. hastata, I. pumilio, and Sympetrum fonscolombii, all of them new hosts for this species. Aquatic mites have been found parasitizing I. hastata females on the island of São Miguel. The prevalence of mite parasitism by Arrenurus sp. on I. hastata was very low, ranging from 12% (2003) to 1% (2008), and in most of the studied ponds, no mites were found attached to females. Although I. hastata coexists with a sexual congener species in the Azores (I. pumilio), they are syntopic in only a small fraction of ponds. Therefore, a comparison between I. hastata and I. pumilio was insufficient to test the predictions of the Red Queen Hypothesis, and further research on parasitism rates in both species needs to be done. In any case, the low prevalence of mite parasitism found in the Azores, coupled with the fact that most of the populations in the archipelago are almost free from competitors and predators, could explain the persistence of these I. hastata parthenogenetic populations, despite their low levels of genetic variation.

Parthenogenetic Ischnura hastata revisited: present status and notes on population ecology and behaviour (Odonata: Coenagrionidae)

Abstract Populations of Ischnura hastata found in the Azores archipelago represent the only known example of parthenogenesis in the order Odonata. In this paper, we present results from fieldwork done on the islands of São Miguel, Pico, Santa Maria, and Graciosa, aimed at characterizing population ecology and habitat preferences of this species. Sampling of several ponds in the islands of São Miguel and Pico showed that I. hastata occurred in oligotrophic ponds, but was absent from all eutrophic ponds sampled, many of which have been impacted by cattle grazing and water extraction by humans. This suggests that parthenogenetic populations are highly sensitive to eutrophication, which may be different from suggested habitat preferences of sexual populations for this species. Mark-recapture studies showed I. hastata to occur in high densities in the studied populations. Although life expectancy of mature females was estimated at less than one week, their high fecundity and fertility could potentially explain the large number of individuals observed in some of the studied sites. Submerged oviposition seems to be a common behaviour, probably evolved as an adaptation to unfavourable climatic conditions and to avoid egg desiccation caused by water depletion. In summary, this work represents a first attempt to study the ecology and population biology of parthenogenetic populations of I. hastata, and may help us to understand the unique conditions under which these populations could have evolved and how to best insure their conservation.

Conservation status of the forest beetles (Insecta, Coleoptera) from Azores, Portugal

Abstract Background Island biodiversity is under considerable pressure due to the ongoing threats of invasive alien species, land use change or climate change. The few remnants of Azorean native forests harbour a unique set of endemic beetles, some of them possibly already extinct or under severe long term threat due to the small areas of the remaining habitats or climatic changes. In this contribution we present the IUCN Red List profiles of 54 forest adapted beetle species endemic to the Azorean archipelago, including species belonging to four speciose families: Zopheridae (12 species), Carabidae (11 species), Curculionidae (11 species) and Staphylinidae (10 species). New information Most species have a restricted distribution (i.e. 66% occur in only one island) and a very small extent of occurrence (EOO) and area of occupancy (AOO). Also common to most of the species is the severe fragmentation of their populations, and a continuing decline in EOO, AOO, habitat quality, number of locations and subpopulations caused by the ongoing threat from pasture intensification, forestry, invasive species and future climatic changes. Therefore, we suggest as future measures of conservation: (1) a long-term monitoring plan for the species; (2) control of invasive species; (3) species-specific conservation action for the most highly threatened species.

New records and detailed distribution and abundance of selected arthropod species collected between 1999 and 2011 in Azorean native forests

Abstract Background In this contribution we present detailed distribution and abundance data for arthropod species identified during the BALA – Biodiversity of Arthropods from the Laurisilva of the Azores (1999-2004) and BALA2 projects (2010-2011) from 18 native forest fragments in seven of the nine Azorean islands (all excluding Graciosa and Corvo islands, which have no native forest left). New information Of the total 286 species identified, 81% were captured between 1999 and 2000, a period during which only 39% of all the samples were collected. On average, arthropod richness for each island increased by 10% during the time frame of these projects. The classes Arachnida, Chilopoda and Diplopoda represent the most remarkable cases of new island records, with more than 30% of the records being novelties. This study stresses the need to expand the approaches applied in these projects to other habitats in the Azores, and more importantly to other less surveyed taxonomic groups (e.g. Diptera and Hymenoptera). These steps are fundamental for getting a more accurate assessment of biodiversity in the archipelago.

Clonal damselflies (Ischnura hastata) are not significantly affected by mite parasitism

We studied parasitism rate by the terrestrial mite Leptus killingtoni Turk (Acari: Erythraeidae) on asexual parthenogenetic damselflies, Ischnura hastata (Say), and sexual Ischnura pumilio (Charpentier) (Odonata: Coenagrionidae) on Pico island (Azores, Portugal). We sampled 52 water bodies on the island and recorded whether Ischnura specimens were parasitized. Half of the water bodies had either dried up or were almost dry or did not have Ischnura populations. In the remaining 23 ponds, mite parasitism was extremely low, with only 3.6% of I. hastata females bearing one or more mites. Ischnura pumilio was rare on the island (61 specimens examined) and had also very few parasites (9.8% parasitism). We examined the biology of the mite and its effects on the host, by studying mite attachment behavior and seasonal abundance, in an intensive study of one pond (Lagoa do Landroal). At this pond, mite prevalence peaked at the start of the sampling period, with 32% of females of I. hastata parasitized and decreased continuously until the end of the study, when only 2% were parasitized. The analysis of mark–recapture histories of 1 748 females of I. hastata indicates that mites did not affect female survival or recapture rate. Our results suggest that L. killingtoni is unlikely to represent a significant selective factor for odonates on the island of Pico, if its density is as low as during the period of our study, although it could be relevant when it is locally abundant or during periods of outbreak.

Species conservation profile of moths (Insecta, Lepidoptera) from Azores, Portugal

Abstract Background The few remnants of Azorean native forests harbour a unique set of endemic moths (Insecta, Lepidoptera), some of them under severe long term threats due to small sized habitats or climatic changes. In this contribution, we present the IUCN Red List profiles of 34 endemic moths to the Azorean archipelago, including species belonging to two diverse families: Noctuidae (11 species) and Crambidae (eight species). The objective of this paper is to assess all endemic Azorean moth species and advise on possible future research and conservation actions critical for the long-trem survival of the most endangered species. New information Most species have a large distribution (i.e. 58% occur in at least four islands), very large extent of occurrence (EOO) and a relatively large area of occupancy (AOO). Only nine species are single-island endemics, three of them from Flores, three from São Miguel and one from Pico, São Jorge and Faial. Most of the species also experience continuing decline in habitat quality, number of locations and subpopulations caused by the ongoing threat from pasture intensification, forestry, invasive plant species and future climatic changes. The lack of new records may indicate that one of the species previously named is extinct (Eupithecia ogilviata). Therefore, we suggest as future conservation actions: (1) a long-term species monitoring plan and (2) control of invasive species.