Canopy insect herbivores in the Azorean Laurisilva forests: key host plant species in a highly generalist insect community

Copyright © ECOGRAPHY 2005.This article explores patterns of insect herbivore distribution in the canopy of the Laurisilva forests on seven islands in the Azores archipelago. To our knowledge, this is one of the first extensive studied of this type in tree or shrub canopies of oceanic island ecosystems. One of the most frequently debated characteristics of such ecosystems is the likely prevalence of vague, ill-defined niches due to taxonomic disharmony, which may have implications for insect-plant interactions. For instance, an increase in ecological opportunities for generalist species is expected due to the lack of predator groups and reduced selection for chemical defence in host plants. The following two questions were addressed: 1) Are specialists rare species, and insect herbivore species randomly distributed among host plant species in the Azores? 2) Are the variances in insect herbivore species composition, frequency and richness explained by host plants or by regional island effects? We expect a proportional distribution of herbivore species between host plants, influenced by host frequency and distinct island effects; otherwise, deviation from expectation might suggest habitat preference for specific host tree crowns. Canopy beating tray samples were performed on seven islands, comprising 50 transects with 1 to 3 plant species each (10 replicates per species), giving 1320 samples from ten host species trees or shrubs in total. From a total of 129 insect herbivore species, a greater number of herbivore species was found on Juniperus brevifolia (s=65) and Erica azorica (s=53). However, the number of herbivore species per individual tree crown was higher for E. azorica than for any other host, on all islands, despite the fact that it was only the fourth more abundant plant. In addition, higher insect species richness and greater insect abundance were found on the trees of Santa Maria Island, the oldest in the archipelago. Insect species composition was strongly influenced by the presence of E. azorica, which was the only host plant with a characteristic fauna across the archipelago, whereas the fauna of other plant crowns was grouped by islands. The great insect occurrence on E. azorica reflects strong habitat fidelity, but only four species were clearly specialists. Our findings indicate a broadly generalist fauna. The simplicity of Azorean Laurisilva contributed to the understanding of insect-plant mechanisms in canopy forest habitats

Relação entre o número de espécies e o número de táxones de alto nível para a fauna de artrópodes dos Açores

Nesta contribuição pretendemos avaliar a aplicação dos modelos RESTAN, "Relação entre o número de Espécies e o número de Táxones de Alto Nível", à fauna de artrópodes de vários habitats das ilhas dos Açores. Utilizámos várias bases de dados recentemente obtidas baseadas em amostragens estandardizadas de artrópodes epígeos do solo em florestas de áreas protegidas, artrópodes fitófagos e predadores de pastagens semeadas e semi-naturais e artrópodes da copa da árvore endémica Juniperus brevifolia. Os modelos RESTAN são aplicados não só usando dados puramente taxonómicos, mas igualmente agrupando os taxa em termos de estratégias ecológicas (e.g. herbívoros, predadores) e de colonização das ilhas (e.g. endémicos). Deste modo pensamos poder avaliar a aplicabilidade destes modelos em estudos de estrutura de comunidades e de conservação. Para os Açores, a aplicação dos modelos RESTAN constitui uma forma muito prática e eficaz de obter estimativas de diversidade. De facto, em todas as matrizes de dados analisadas a riqueza de espécies pode ser estimada eficazmente usando apenas a riqueza em géneros, sendo a relação linear. Ao nível da família, os modelos estimadores possuem um menor poder explicativo e são melhor explicados por uma função exponencial. O escalonamento de Reservas Florestais Naturais dos Açores em termos de biodiversidade de artrópodes endémicos pode ser efectuado usando informação taxonómica ao nível do género. A aplicação de métodos de estimativa rápida de biodiversidade fica assim facilitada, podendo usar-se parataxonomistas bem treinados para o processo de triagem do grande número de amostras geralmente necessárias em estudos ecológicos. Discute-se igualmente a aplicabilidade dos modelos RESTAN a dados de diversidade alfa, beta e gama.ABSTRACT: In this contribution we examine the predictive power of numbers of higher taxa (orders, families and genera) as surrogates of species richness ("RESTAN" models – models based on linear relationship between species and higher taxa numbers) for the Azorean arthropod fauna. Recently, two large entomological and ecological studies were performed in the Azores, using standardized sampling protocols to estimate the diversity of arthropods in grassland and native forests. We use datasets available from those studies to address a few technical questions: A. what is the impact of using several measures of diversity (alpha, gamma and beta species diversity; Shannon-Wiener index of diversity; Evenness) based on numbers of families and genera for canopy arthropods? For instance, could be predicted that values of beta-diversity decrease with the use of higher-taxa estimates. All the measures of diversity could be used, being the genera the best predictor; B. how well behave the RESTAN models for functional groups of species like grass-feeding and web-building spiders in grasslands? The predictive power of higher-taxa is low using web-building spiders, due to few families being envolved and some genera having many species locally represented; C. assuming at least one sample with no species then there will be also no highertaxa in that sample. Consequently, the curve of the relationship between highertaxa richness and species richness should be anchored to the origin (y= bx). What is the predictive value of this model in comparison with the linear (y =a + bx), log-log (log y = a + b log x) and exponential (y = A • e b x) models? The best fit was obtained with the linear model for the genus-species relationship, but the variables are not normally distributed and the log-log model should be preferable. For the family-species relationship the exponential model is the best. The linear model anchored to the origin (y =bx) has some statistical pitfalls and was of less predictive value; D. in conservation studies what is the predictive value of higher-taxa in ranking protected areas? We found that the numbers of arthropod genera could successfully rank the Natural Forest Reserves as well as numbers of species (using endemic species dataset). We found that in the Azores the predictions of species richness using higher-taxa are quite reasonable, mainly because of low levels of diversity. Therefore, costeffective studies could use only genera, since the species richness of arthropods could be predicted reasonably closely from their genus-level richness. Family and order-level data were less informative for all datasets. We suggest that in the Azores as a consequence of the low levels of species diversification with a great proportion of monospecific genera, the use of parataxonomists trained in genus-level identification could be appropriate for sorting large numbers of ecological samples

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

Copyright © Springer 2005.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

Philaenus spumarius (Linnaeus, 1758) new to the Azores (Homoptera, Auchenorrhyncha, Cercopidae)

V Congresso Ibérico de Entomologia, Lisboa, 9 a 13 de Novembro de 1992.Philaenus spumarius (Linnaeus, 1758) (Homoptera, Auchenorrhyncha, Cercopidae), uma novidade faunística para os Açores - A cigarrinha espumosa (Philaenus spumarius), um cercopídeo notável pelo seu elevado grau de polimorfismo cromático, é dada pela primeira vez para os Açores, tendo sido encontrada em S. Miguel. Nos machos foram encontradas as seguintes formas: typicus (TYP), populi (POP) e leucophthalmus (LOP); quanto às fêmeas, apenas foram encontradas as formas typicus (TYP) e populi (POP). No que respeita ao edeago, o material aqui estudado aproxima-se bastante dos exemplares encontrados no norte de Portugal, onde as condições ecológicas mais se aproximam das dos Açores.ABSTRACT: The meadow spittlebug, Philaenus spumarius, a well known highly polymorphic cercopid for colour pattern, is here recorded for the first time from the Azores, having been found so far in S. Miguel. Only the morphs typicus (TYP), populi (POP), and leucophthalmus (LOP), on males, and typicus (TYP) and populi (-POP), on females, were found. Moreover, in the structure of the aedeagus the specimens conform well to material from northern continental Portugal, where the ecological conditions are close to those of the Azores

Canopy insect herbivores in the Azorean Laurisilva forests: key host plant species in a highly generalist insect community

Copyright © ECOGRAPHY 2005.This article explores patterns of insect herbivore distribution in the canopy of the Laurisilva forests on seven islands in the Azores archipelago. To our knowledge, this is one of the first extensive studied of this type in tree or shrub canopies of oceanic island ecosystems. One of the most frequently debated characteristics of such ecosystems is the likely prevalence of vague, ill-defined niches due to taxonomic disharmony, which may have implications for insect-plant interactions. For instance, an increase in ecological opportunities for generalist species is expected due to the lack of predator groups and reduced selection for chemical defence in host plants. The following two questions were addressed: 1) Are specialists rare species, and insect herbivore species randomly distributed among host plant species in the Azores? 2) Are the variances in insect herbivore species composition, frequency and richness explained by host plants or by regional island effects? We expect a proportional distribution of herbivore species between host plants, influenced by host frequency and distinct island effects; otherwise, deviation from expectation might suggest habitat preference for specific host tree crowns. Canopy beating tray samples were performed on seven islands, comprising 50 transects with 1 to 3 plant species each (10 replicates per species), giving 1320 samples from ten host species trees or shrubs in total. From a total of 129 insect herbivore species, a greater number of herbivore species was found on Juniperus brevifolia (s=65) and Erica azorica (s=53). However, the number of herbivore species per individual tree crown was higher for E. azorica than for any other host, on all islands, despite the fact that it was only the fourth more abundant plant. In addition, higher insect species richness and greater insect abundance were found on the trees of Santa Maria Island, the oldest in the archipelago. Insect species composition was strongly influenced by the presence of E. azorica, which was the only host plant with a characteristic fauna across the archipelago, whereas the fauna of other plant crowns was grouped by islands. The great insect occurrence on E. azorica reflects strong habitat fidelity, but only four species were clearly specialists. Our findings indicate a broadly generalist fauna. The simplicity of Azorean Laurisilva contributed to the understanding of insect-plant mechanisms in canopy forest habitats

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

Copyright © Springer 2005.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

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

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).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

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

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).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