Interaction Networks Help to Infer the Vulnerability of the Saproxylic Beetle Communities That Inhabit Tree Hollows in Mediterranean Forests.

Insect communities are facing contrasting responses due to global change. However, knowledge on impacts of communities' reorganizations is scarce. Network approaches could help to envision community changes in different environmental scenarios. Saproxylic beetles were selected to examine long-term variations in insect interaction/diversity patterns and their vulnerability to global change. We evaluated interannual differences in network patterns in the tree hollow-saproxylic beetle interaction using absolute samplings over an 11-year interval in three Mediterranean woodland types. We explored saproxylic communities' vulnerability to microhabitat loss via simulated extinctions and by recreating threat scenarios based on decreasing microhabitat suitability. Although temporal diversity patterns varied between woodland types, network descriptors showed an interaction decline. The temporal beta-diversity of interactions depended more on interaction than on species turnover. Interaction and diversity temporal shifts promoted less specialized and more vulnerable networks, which is particularly worrisome in the riparian woodland. Network procedures evidenced that saproxylic communities are more vulnerable today than 11 years ago irrespective of whether species richness increased or decreased, and the situation could worsen in the future depending on tree hollow suitability. Network approaches were useful for predicting saproxylic communities' vulnerability across temporal scenarios and, thus, for providing valuable information for management and conservation programs.

Sex specificity of dispersal behaviour and flight morphology varies among tree hollow beetle species.

BACKGROUND: Flight performance and dispersal behaviour can differ between sexes, resulting in sex-biased dispersal. The primary sex ratio of populations may also explain dispersal bias between sexes, as this bias may evolve with the primary sex ratio to reduce intrasexual competition. Although dispersal bias between sexes is relevant to population dynamics, there are few studies on sex-biased dispersal in insects. We studied the flight performance and dispersal behaviour of seven saproxylic beetle species associated with tree hollows from a sex perspective. We also analysed the possible coevolution of flight performance with the primary sex ratio. METHODS: Wing loading and wing aspect ratio were used as measures of the flight performance of species and sexes. Dispersal behaviour was explored by analysing the frequency of each sex in interception traps versus the primary sex ratio obtained by tree hollow emergence traps using contingency tables and posthoc standardized residuals. A more active flight behaviour was expected for the sex with higher capture frequency in the interception traps. To explore the causes of flight performance bias between sexes, we searched for possible correlations between wing loading or wing aspect ratio and primary sex ratio using Pearson's correlation coefficient. RESULTS: Wing loading and wing aspect ratio differed between species and sexes, with flight performance being higher in males than in females for four of the seven species analysed. Dispersal behaviour and flight performance matched in the case of Elater ferrugineus; males showed higher flight performance and were the most collected sex in the interception traps (more active flyers). In contrast, the higher flight activity of Cetonia carthami aurataeformis females was not correlated with a higher flight performance than that of males. Moreover, we found that a bias in the primary sex ratio towards females is often correlated with a decrease in female flight performance. CONCLUSIONS: We stress that flight performance and dispersal behaviour of sexes do not always go hand in hand. Moreover, the relationship between the sex ratio and flight performance bias between sexes is not driven by competition within the most abundant sex. The inclusion of a sex perspective in insect dispersal studies would be useful to detect dispersal bias between sexes and its causes and would allow for further analysis of its effects on population dynamics.

Author Correction: Contrasting functional structure of saproxylic beetle assemblages associated to different microhabitats.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Contrasting functional structure of saproxylic beetle assemblages associated to different microhabitats.

Saproxylic beetles depend on diverse microhabitats that are exploited by different species assemblages. We focused on anlyse the functional trait patterns and functional diversity components of two main assemblages that were collected with window traps (WTs) and hollow emergence traps (HETs) respectively, between three protected areas of the Iberian Peninsula. For that we measured phenological, physiological, morphological, and ecological traits. Results showed that the main microhabitats exploited by each assemblage (WT and HET) constrain most of the morphological traits and trophic guilds. In addition, relative elytra length and predator guild, together with adult activity period, responded to differences at the habitat level (among study areas). HET assemblages were less taxonomically diverse but more functionally diverse than those of WTs, enhancing the functional relevance of tree hollows. Additionally, niche filtering dominated WT assemblages, which were characterised by a narrower functional space and a higher redundancy. In contrast, in the HET assemblages the coexistence of functionally dissimilar species is driven by the niche heterogeneity. HET and WT assemblages differed in the functional space occupied by each within areas, but both assemblages reflected coincident patterns among areas that pointed to a reduction of functional space with management.

Saproxylic Cetoniidae (Coleoptera: Scarabaeoidea): A 'Females' World' or a Question of Dependence on Deadwood?

We explored the dependence of some Cetoniidae species on saproxylic environments and microhabitats in a Mediterranean oak forest by analyzing species collected using different kinds of traps-log emergence, hollow emergence, and interception traps-and the sex ratio of the species in each trap. Comparing the sex ratio of the species collected via emergence versus interception was useful to unravel the degree of dependence on saproxylic microhabitats. Among the species studied, Cetonia aurataeformis Curti, 1913 (Coleoptera: Cetoniidae) was the only obligate tree hollow inhabitant. Special attention should thus be paid to the maintenance of tree hollows for the species' conservation in Mediterranean forests. A gradient of dependence on tree hollows was established from the more dependent Protaetia (Potosia) cuprea (Fabricius, 1775) (Coleoptera: Cetoniidae) and Protaetia (Potosia) opaca (Fabricius, 1787) (Coleoptera: Cetoniidae) to the less dependent Protaetia (Netocia) morio (Fabricius, 1781) (Coleoptera: Cetoniidae). All the latter species can be considered facultatively dependent, to varying degrees, on tree hollows. By contrast, the saproxylic affinity of Protaetia (Netocia) oblonga (Gory and Percheron, 1833) (Coleoptera: Cetoniidae), Tropinota squalida (Scopoli, 1783) (Coleoptera: Cetoniidae) and Oxythyrea funesta (Poda, 1761) (Coleoptera: Cetoniidae) was doubtful. Generally, the sex ratio of the studied species was female-biased. A possible explanation may be local male competition for females, suggesting the Cetoniinae is a female world. However, the range of difference in the female-biased sex ratio among species suggests it is important to explore other possible causes, such as differences in dispersal abilities.

Diversity and deadwood-based interaction networks of saproxylic beetles in remnants of riparian cloud forest.

We studied the saproxylic beetle community inhabiting deadwood in remnants of riparian cloud forests in "La Antigua" basin, in central Veracruz (Mexico). We assessed the influence of deadwood features (tree species, trunk position, trunk diameter, trunk volume and decomposition stages) on saproxylic beetle diversity. In order to assess the stability of beetle species-deadwood interactions, we also analyzed the ecological networks structure. A total of 63 deadwood trunks, belonging to four tree species, were sampled by standardized hand-collection throughout well-preserved remnants of riparian cloud forest. We found that tree species and deadwood decay stage are the main drivers that determine the diversity and stability of saproxylic beetle species interactions. Our results indicate that Quercus corrugata is the main tree species in terms of maintaining the significantly highest saproxylic beetle diversity, but with no stable interactions (saproxylic beetle-deadwood). A nested network structure was detected for Clethra mexicana and Liquidambar styraciflua, with a pool of core (generalist) saproxylic beetle species. We observed that beetle diversity from the early and late deadwood stages comprises distinct assemblages and the four stages of decomposition showed a nested network structure. During deadwood succession, community composition and guilds changed among networks; the early successional stage had more specialized xylophagous beetles, while other guilds (mycophagous, saprophagous and zoophagous) arrive later and become the core species in the advanced stages of decomposition networks. Heliscus tropicus (Passalidae) is a key species constituting the core of all of the networks and could be considered an ecosystem engineer in cloud forests. By exploring links between saproxylic beetles and deadwood characteristics, we can further our understanding of species interaction in order to develop management strategies oriented towards the protection of species and their habitats in this threatened ecosystem.

New species of Pseudoscorpiones (Arachnida) from tree hollows in a Mediterranean oak forest in Spain.

Pseudoscorpions inhabiting mature Quercus pyrenaica Willd. trees have been surveyed using hollow emergence traps and window traps in Salamanca, Spain. Three new species are described: Neobisium (N.) hispanicum Zaragoza Hernández-Corral, n. sp., Rhacochelifer gaeli Zaragoza Hernández-Corral, n. sp. and Rhacochelifer nonidezi Zaragoza Hernández-Corral, n. sp. The genera Amblyolpium Simon, 1898 and Beierochelifer Mahnert, 1977 and the species Amblyolpium dollfusi Simon, 1898 and Beierochelifer peloponnesiacus (Beier, 1929) are new records for the Iberian Peninsula. Beierochelifer peloponnesiacus jonicus (Beier, 1932) is shown to be a junior subjective synonym of B. peloponnesiacus n. syn. New regional records of five other species belonging to the families Cheliferidae, Chernetidae and Withiidae are given. Keys are given for the species of the genera Pseudorhacochelifer Beier, 1976 and Rhacochelifer Beier, 1932 with elongated keels on posterolateral corners of carapace and anterior tergites in males, and for the Rhacochelifer species of the Iberian Peninsula. Complementary data to the description of the female syntypes from Caravaca (Murcia, mainland Spain) and males from the Canary Islands of Rhacochelifer pinicola (Nonídez, 1917) are given. Brief redescriptions of the female of Neobisium (N.) maroccanum Beier, 1930 and the male of Rhacochelifer euboicus Mahnert, 1977 are provided. The previous record of R. disjunctus from Slovakia is shown to be an error for R. euboicus. New data on the distribution and habitats of species of Cheliferidae, Chernetidae and Withiidae are given.

Unraveling Saproxylic Insect Interactions in Tree Hollows from Iberian Mediterranean Forest.

Tree hollows are complex microhabitats in which a variety of abiotic and biotic factors shape the community assembly of saproxylic insects. Detecting non-random species co-occurrence patterns is a fundamental goal in ecology in order to understand the assembly mechanisms of communities. We study association patterns of species of Coleoptera and Diptera (Syrphidae), belonging to different trophic guilds, on 72 tree hollows at a local and regional scale in three protected areas in Mediterranean forests using a fixed-fixed null model. Our matrix-level analysis shows a tendency for segregation in species association (species exclusion) at the regional and site levels. However, the high complexity of tree-hollow habitats, offering different resources for a more or less specialized fauna, makes it difficult to prove competition interactions. Indeed, pairwise analysis shows a dominance of non-random aggregation patterns (species coexistence) at the local and regional levels. Both aggregation and segregation of non-random patterns were more common among species from different trophic guilds than within the same guilds, with predators being a common denominator for a high percentage of the inter-guild pairs. Our results suggest that predation and facilitation interactions, together with habitat segregation, are the main factors shaping tree-hollow assemblages, while competition seems to be less important. We conclude that species interactions take an important part of the process of assemblage structuration and special attention should be paid to 'ecosystem engineers' and threatened species in the conservation of tree hollow assemblages.

Checklist and identification key of Anomalini (Coleoptera, Scarabaeidae, Rutelinae) of Costa Rica.

A checklist and identification key for the species of the tribe Anomalini in Costa Rica are presented. The Anomalini species are important economically, as they have larvae that are or can become agricultural pests, as well as ecologically, having potential as bioindicators. In spite of their importance and richness, identification tools for the group in the Neotropics remain scarce. The Costa Rican fauna comprises six genera (Anomala, Anomalorhina, Callistethus, Epectinaspis, Moroniella, and Strigoderma) and a total of 120 species. Anomala contusa Filippini, Micó, Galante, 2015 is proposed as a synonym of Anomala inbio (Ramírez-Ponce, Bitar, Curoe 2014); Anomala limonnom. n. is proposed as a new name for Anomala inbio Filippini, Galante, Micó, 2015, a homonym of Anomala inbio (Ramírez-Ponce, Bitar, Curoe, 2014); Anomala cinaediasnom. n. is proposed as a new name for Anomala chloropyga Ohaus, 1897, a homonym of Anomala chloropyga Burmeister, 1844; and Anomala chrysomelina is moved to the genus Callistethus.

ResumenPresentamos el listado y la clave de identificación de las especies de la tribu Anomalini de Costa Rica. Las especies de Anomalini son importantes económica, con larvas que son o pueden ser plagas agrícolas, y ecológicamente, con un potencial como bioindicadores. A pesar de su importancia y riqueza, los instrumentos de identificación para el grupo para el Neoptrópico son todavía escasos. La fauna de Costa Rica está compuesta por seis géneros (Anomala, Anomalorhina, Callistethus, Epectinaspis, Moroniella y Strigoderma) y un total de 120 especies. Anomala contusa Filippini, Micó, Galante, 2015 se propone como sinónimo de Anomala inbio (Ramírez-Ponce, Bitar, Curoe, 2014); Anomala limon se propone como nuevo nombre de Anomala inbio Filippini, Galante, Micó, 2015, homónimo de Anomala inbio (Ramírez-Ponce, Bitar, Curoe, 2014); Anomala cinaedias se propone como nuevo nombre de Anomala chloropyga Ohaus, 1897, homónimo de Anomala chloropyga Burmeister, 1844; Anomala chrysomelina se mueve al género Callistethus.

Description of six new species of Anomalini from Costa Rica (Coleoptera: Scarabaeidae: Rutelinae).

Four new species of Anomala Samouelle and two new species of Callistethus Blanchard (Coleoptera: Scarabaeidae: Rutelinae: Anomalini) from Costa Rica are described: A. aglaos new species, A. estrella new species, A. inbio new species, A. pincelada new species, C. ruteloides new species, and C. yalizo new species. A distribution map of each species is given and the male genitalia (aedeagus and endophallus) of the species described and similar species are illustrated.

Association patterns in saproxylic insect networks in three Iberian Mediterranean woodlands and their resistance to microhabitat loss.

The assessment of the relationship between species diversity, species interactions and environmental characteristics is indispensable for understanding network architecture and ecological distribution in complex networks. Saproxylic insect communities inhabiting tree hollow microhabitats within Mediterranean woodlands are highly dependent on woodland configuration and on microhabitat supply they harbor, so can be studied under the network analysis perspective. We assessed the differences in interacting patterns according to woodland site, and analysed the importance of functional species in modelling network architecture. We then evaluated their implications for saproxylic assemblages' persistence, through simulations of three possible scenarios of loss of tree hollow microhabitat. Tree hollow-saproxylic insect networks per woodland site presented a significant nested pattern. Those woodlands with higher complexity of tree individuals and tree hollow microhabitats also housed higher species/interactions diversity and complexity of saproxylic networks, and exhibited a higher degree of nestedness, suggesting that a higher woodland complexity positively influences saproxylic diversity and interaction complexity, thus determining higher degree of nestedness. Moreover, the number of insects acting as key interconnectors (nodes falling into the core region, using core/periphery tests) was similar among woodland sites, but the species identity varied on each. Such differences in insect core composition among woodland sites suggest the functional role they depict at woodland scale. Tree hollows acting as core corresponded with large tree hollows near the ground and simultaneously housing various breeding microsites, whereas core insects were species mediating relevant ecological interactions within saproxylic communities, e.g. predation, competitive or facilitation interactions. Differences in network patterns and tree hollow characteristics among woodland sites clearly defined different sensitivity to microhabitat loss, and higher saproxylic diversity and woodland complexity showed positive relation with robustness. These results highlight that woodland complexity goes hand in hand with biotic and ecological complexity of saproxylic networks, and together exhibited positive effects on network robustness.

Redescription of Anomala eucoma Bates, 1888 and a description of three new species from Costa Rica (Coleoptera: Scarabaeidae: Rutelinae).

Anomala eucoma Bates, 1888 is redescribed and a lectotype from Guatemala is designated. Three new species from Costa Rica, A. flavacoma new species, A. megaparamera new species, and A. pseudoeucoma new species, are described, and a distribution map is given. The internal sac (endophallus) of the species covered is illustrated, and its use in separating closely related species in this region is discussed. An identification key for morphologically similar species from the Neotropical region is provided.

Breaking down complex Saproxylic communities: understanding sub-networks structure and implications to network robustness.

Saproxylic insect communities inhabiting tree hollow microhabitats correspond with large food webs which simultaneously are constituted by multiple types of plant-animal and animal-animal interactions, according to the use of trophic resources (wood- and insect-dependent sub-networks), or to trophic habits or interaction types (xylophagous, saprophagous, xylomycetophagous, predators and commensals). We quantitatively assessed which properties of specialised networks were present in a complex networks involving different interacting types such as saproxylic community, and how they can be organised in trophic food webs. The architecture, interacting patterns and food web composition were evaluated along sub-networks, analysing their implications to network robustness from random and directed extinction simulations. A structure of large and cohesive modules with weakly connected nodes was observed throughout saproxylic sub-networks, composing the main food webs constituting this community. Insect-dependent sub-networks were more modular than wood-dependent sub-networks. Wood-dependent sub-networks presented higher species degree, connectance, links, linkage density, interaction strength, and were less specialised and more aggregated than insect-dependent sub-networks. These attributes defined high network robustness in wood-dependent sub-networks. Finally, our results emphasise the relevance of modularity, differences among interacting types and interrelations among them in modelling the structure of saproxylic communities and in determining their stability.

Sampling scarab beetles in tropical forests: the effect of light source and night sampling periods.

Light traps have been used widely to sample insect abundance and diversity, but their performance for sampling scarab beetles in tropical forests based on light source type and sampling hours throughout the night has not been evaluated. The efficiency of mercury-vapour lamps, cool white light and ultraviolet light sources in attracting Dynastinae, Melolonthinae and Rutelinae scarab beetles, and the most adequate period of the night to carry out the sampling was tested in different forest areas of Costa Rica. Our results showed that light source wavelengths and hours of sampling influenced scarab beetle catches. No significant differences were observed in trap performance between the ultraviolet light and mercury-vapour traps, whereas these two methods caught significantly more species richness and abundance than cool white light traps. Species composition also varied between methods. Large differences appear between catches in the sampling period, with the first five hours of the night being more effective than the last five hours. Because of their high efficiency and logistic advantages, we recommend ultraviolet light traps deployed during the first hours of the night as the best sampling method for biodiversity studies of those scarab beetles in tropical forests.