Saproxylic Insects Research Articles

Newly Woody Artificial Diet Reveals Antibacterial Activity of Hemolymph in Larvae of Zophobas atratus (Fabricius, 1775) (Coleoptera: Tenebrionidae).

The rearing of saproxylic insects in laboratory conditions is an important task for studying the biology of insects. Through understanding nutritional needs, it is possible to optimize beetle rearing in laboratory conditions. In this study, an artificial fungi-based diet (FD) was developed for the cultivation of the darkling beetle Zophobas atratus (Fabricius, 1775) (Coleoptera: Tenebrionidae) in laboratory conditions as a model object for studying the biology of saproxylophagous beetles. To assess the influence of the diet, a number of physiological parameters were measured, including development time, body size, and weight of all stages of the beetle's life cycle, as well as its immune status. The immune status of Z. atratus was assessed on the basis of larval hemolymph antibacterial activity against six different bacterial strains assessed using disk-diffusion and photometric tests. Our findings show that the FD reduces development time and boosts the immune status as compared to beetles reared on a standard diet (SD). Samples from FD-reared larvae had pronounced antibacterial activity as compared to samples from SD-reared larvae. This work is of fundamental importance for understanding the correlations between nutrition and development of saproxylic Coleoptera and is the first report on immune status regulation in this group of insects.

The first mitogenomic phylogenetic framework of Dorcus sensu lato (Coleoptera: Lucanidae), with an emphasis on generic taxonomy in Eastern Asia

BackgroundDorcus stag beetles in broad sense are one of the most diverse group in Lucanidae and important saproxylic insects playing a crucial role in nutrient recycling and forest biomonitoring. However, the dazzling morphological differentiations have caused numerous systematic confusion within the big genus, especially the puzzlingly generic taxonomy. So far, there is lack of molecular phylogenetic study to address the chaotic situation. In this study, we undertook mitochondrial genome sequencing of 42 representative species including 18 newly-sequenced ones from Eastern Asia and reconstructed the phylogenetic framework of stag beetles in Dorcus sensu lato for the first time.ResultsThe mitogenome datasets of Dorcus species have indicated the variable mitogenomic lengths ranged from 15,785 to 19,813 bp. Each mitogenome contained 13 PCGs, 2 rRNAs, 22 tRNAs, and a control region, and all PCGs were under strong purifying selection (Ka/Ks < 1). Notably, we have identified the presence of a substantial intergenic spacer (IGS) between the trnAser (UCN) and NAD1 genes, with varying lengths ranging from 129 bp (in D. hansi) to 158 bp (in D. tityus). The mitogenomic phylogenetic analysis of 42 species showed that Eastern Asia Dorcus was monophyletic, and divided into eight clades with significant genetic distance. Four of them, Clade VIII, VII, VI and I are clustered by the representative species of Serrognathus Motschulsky, Kirchnerius Schenk, Falcicornis Séguy and Dorcus s.s. respectively, which supported their fully generic positions as the previous morphological study presented. The topology also showed the remaining clades were distinctly separated from the species of Dorcus sensu lato, which implied that each of them might demonstrate independent generic status. The Linnaeus nomenclatures were suggested as Eurydorcus Didier stat. res., Eurytrachellelus Didier stat. res., Hemisodorcus Thomson stat. res. and Velutinodorcus Maes stat. res. For Clade V, IV, III and II respectively.ConclusionThis study recognized the monophyly of Dorcus stag beetles and provided a framework for the molecular phylogeny of this group for the first time. The newly generated mitogenomic data serves as a valuable resource for future investigations on lucanid beetles. The generic relationship would facilitate the systematics of Dorcus stag beetles and thus be useful for exploring their evolutionary, ecological, and conservation aspects.

Investigation of Fungal Community Structure in the Gut of the Stag Beetle Dorcus hopei (Coleoptera; Lucanidae): Comparisons Among Developmental Stages

Stag beetles, recognized as common saproxylic insects, are valued for their vibrant coloration and distinctive morphology. These beetles play a crucial ecological role in decomposition and nutrient cycling, serving as a vital functional component in ecosystem functioning. Although previous studies have confirmed that stag beetles are predominantly fungivores, the fluctuations in their intestinal fungal communities at different developmental stages remain poorly understood. In the current study, high-throughput sequencing was employed to investigate the dynamic changes within intestinal fungal communities at various developmental stages in the stag beetle Dorcus hopei. Results showed that microbial diversity was higher during the larval stage than during the pupal and adult stages. Furthermore, significant differences were identified in the composition of the intestinal fungal communities across the larval, pupal, and adult stages, suggesting that developmental transitions may be crucial factors contributing to variations in fungal community composition and diversity. Dominant genera included Candida, Scheffersomyces, Phaeoacremonium, and Trichosporon. Functional predictions indicated a greater diversity and relative abundance of endosymbiotic fungi in the larval gut, suggesting a potential dependency of larvae on beneficial gut fungi for nutrient acquisition. Additionally, the application of abundance-based β-null deviation and niche width analyses revealed that the adult gut exerted a stronger selection pressure on its fungal community, favoring certain taxa. This selection process culminates in a more robust co-occurrence network of fungal communities within the adult gut, thereby enhancing their adaptability to environmental fluctuations. This study advances our understanding of the intestinal fungal community structure in stag beetles, providing a crucial theoretical foundation for the development of saproxylic beetle resources, biomass energy utilization, plastic degradation strategies, and beetle conservation efforts.

Effects of Eucalyptus wood and leaf litter on saproxylic insects in the southeastern United States

Although Eucalyptus is widely planted outside its native range for timber and pulp production, the effects of these exotic plantations on biodiversity relative to native semi-natural forests or plantations of native tree species remain incompletely understood. Here, we compare the diversity of saproxylic beetles (Coleoptera) and true bugs (Hemiptera) between non-native Eucalyptus benthamii Maiden and Cambage (Camden white gum) and native Pinus taeda L. (loblolly pine) stands on the upper Coastal Plain of South Carolina, U.S.A. We sampled insects emerging from logs of both species placed in both stand types after 1, 2, 6, and 12 months in the field. Beetle and true bug richness and diversity were both significantly lower from eucalypt than from pine wood. Moreover, the two communities were compositionally distinct. Whereas pine supported many species of host-specific phloeoxylophagous beetles, most species collected from eucalypts were mycophagous or predatory taxa capable of utilizing a wide range of hosts. Species richness did not differ between logs placed in eucalypt vs. pine stands but Shannon’s diversity was significantly higher in the eucalypt stands, possibly due to greater sun exposure in the latter. Contrary to a previous study, we found no support for the idea that eucalypt litter reduces the diversity of saproxylic insects. Our findings add to the growing body of evidence that non-native plantations are less favorable to biodiversity than those consisting of native tree species.

Microbiotope selection in saproxylic bees and wasps (Hymenoptera, Aculeata): cavity-nesting communities in forests and wooded pastures are affected by variation in openness but not deadwood

Saproxylic insects are an important component of forest biodiversity; however, their ecological requirements are mostly studied on beetles, while other groups are less considered. Aculeate Hymenoptera provide valuable ecosystem services, and some rely on deadwood cavities. We studied cavity-nesting aculeate Hymenoptera using wooden trap-nests set in a heterogeneous partially rewilded woodland area in Central Bohemia, Czech Republic, and tested their nesting preferences in association with canopy openness, amount of deadwood, and the diversity of surrounding vegetation types. We used 100 trap-nests in five microbiotopes—forest edge, shady closed-canopy forest, open patches in closed-canopy forest, open-grown trees in wooded pasture, and shady groves in wooded pasture, over 2 years. We reared 824 specimens belonging to 26 species of saproxylic hymenopterans. We found no effect of microbiotope on total species richness and richness of nest parasites, but richness of nest builders was highest in forest edge and lowest in open-grown trees in wooded pasture. Species composition of hymenopterans was driven by a wider habitat context: despite the proximity of the habitats, the forest, especially closed-canopy patches, hosted a different community, dominated by wasps, than open wooded pasture. Moreover, open patches in forest differed in composition from the closed-canopy patches, suggesting that in production forests, the diversity of saproxylic hymenopterans may be limited by the overall low share of open canopy stages. Deadwood (amount and diversity) did not affect the saproxylic bees and wasps in any way.Implications for insect conservationOur results support conservation measures leading to diversification of the forest canopy and vegetation structure in order to support rich communities of saproxylic Hymenoptera, especially in protected areas.

Decomposition of bark beetle-attacked trees after mortality varies across forests

Bark beetle outbreaks result in massive amounts of deadwood which are a significant carbon reservoir that can impact forest ecosystems. Additionally, bark beetle-introduced symbiotic fungi in beetle-generated deadwood can increase termite presence and feeding. This could alter decomposition rates and saproxylic communities of bark beetle-generated deadwood. However, the fate of bark beetle-generated deadwood after tree mortality has received little attention despite the possibility bark beetles could alter decomposition processes and deadwood residence times at landscape scales following outbreaks. We tested the hypothesis that beetle-attacked trees decompose faster than unattacked trees. In Honduras, and Mississippi and Arizona, USA, we felled one recently bark beetle-attacked and one apparently healthy conspecific tree at each site that was cut into 120 experimental logs. Logs of each tree (attacked or unattacked) were assigned one of three metal mesh covering treatments: 1) fully covered to exclude all macroinvertebrates, 2) covered from above to exclude secondary bark beetle colonization, 3) no cover to allow all detrital food web organisms. Half of all logs at each site was collected after 1 and 2 years and the density loss, insect visual damage rating, and abundance of termites, ants, and beetles was measured. Bark beetle attack had the largest impacts at higher latitude and western forests: density loss between attacked and unattacked logs was consistently higher in Arizona (Flagstaff), initially slower (year 1) in Mississippi, but faster between years 1 and 2 resulting in similar density loss after 2 years, and did not differ in Honduras. Saproxylic insect wood damage rating accounted for 30% of the variation in decomposition across sites. Thus, decomposition rates of deadwood following bark beetle attack are highly variable across their geography and likely reflect important interactions among saproxylic organisms. This has implications for forest ecology and management including forest modeling with regard to carbon cycling and maintaining biodiversity of saproxylic organisms.

A NEW FIELD EMERGENCE TRAP FOR SAMPLING INSECTS FROM PRECISE AREAS OF LOGS

A new emergence trap was fabricated for collecting saproxylic insects from precise areas of dead and fallen trees. The trap works on the principle of all emergence traps, i.e., organisms emerging from a substrate get attracted towards light, where they encounter a transparent surface and get collected in a collecting tube with preservative fluid. It is one of the most objective methods for sampling saproxylic insects as they emerge from wood substrata. Using many replicates of this trap, the entire heterogeneity of a substratum like dead wood can be easily covered. The trap can provide a higher definition of the sampling area and be used for studying assemblages of saproxylic insects. It is almost cost-effective and user-friendly under field conditions, on logs and snags, and even on live trees. In this study, 102 such field emergence traps were deployed in a conserved area, and 59 species of saproxylic insects belonging to 5 functional groups were collected during a brief sampling period of 3 months. Extensive sampling trials using such traps in more numbers for extended periods can provide insights into species? diversity and host preferences.. KEYWORDS :Emergence Trap, Insect Diversity, Insect Sampling, Saproxylic Insects, Xylophagous Insects

Morphometric traits of Dorcus parallelipipedus (Coleoptera: Lucanidae) larvae and adults: can differences between populations be ruled out?

Summary Stag beetles are saproxylic insects that live in deadwood colonised by fungi and other microorganisms. Due to the cryptic habits of these species, little is known on their biological aspects, especially for the immature stage. In this study, we investigated morphometric traits of lesser stag beetle, Dorcus parallelipipedus (Linnaeus, 1758) (Coleoptera: Lucanidae) larvae and adults, with comparisons between populations. Instar identification by measuring larval head capsule was performed, and the relationship between larval body mass and head capsule width was investigated for each surveyed population. To assess the differences among populations, the scaling relationships for adults between their body and mandibles length was also considered, especially for adult males. Morphometric relationships were described by exponential equations. Differences between populations were sometimes limited to one or the other feature, and particularly ascribed to the larval body mass. These differences could be imputed to several factors, among with those of environmental or genetic order. The scaling relationship of lesser stag beetle adult males showed a positive allometry but did not differ among populations, indicating that morphological traits within a species and sex may be biologically retained. Findings are discussed from the perspective of D. parallelipipedus life history.

Bark beetle and woodborer responses to stand thinning and prescribed fire in northeastern US coastal and inland pitch pine barrens

Abstract Southern pine beetle, Dendroctonus frontalis, has expanded its range further into the northeastern United States. This expansion threatens rare and ecologically valuable interior and coastal pitch pine barrens. Pitch pine barrens restoration and southern pine beetle infestation suppression often involve leaving downed dead wood that saproxylic insects can exploit. Semiochemical‐baited traps were used to investigate the response of bark beetles and woodborers to restoration treatments at Rocky Point State Forest and the Albany Pine Bush Preserve, examples of coastal and interior pitch pine forests, respectively. A total of 29,598 saproxylic insects from 116 species of bark beetles and woodborers were captured at Rocky Point State Forest, while 23,117 individuals from 67 species were captured at Albany Pine Bush Preserve. Ips spp. were abundant at both sites with 28%–47% and 42%–74% of total collections at Rocky Point State Forest and Albany Pine Bush Preserve, respectively. Ips grandicollis did not respond to treatments at either site. However, Ips pini was found in higher numbers in thinned blocks in Rocky Point State Forest.

Saproxylic Hymenoptera in dead wood retained on clear cuts, relation to wood parameters and their degree of specialisation

Intensive forestry is a threat to biodiversity, and therefore actions are made to mitigate this loss. The actions are, however, designed based on available knowledge about the requirements of species, and for saproxylic insects this concerns mainly Coleoptera, while the diverse but poorly known Hymenoptera has contributed less. In this paper we therefore asked whether the substrate requirements of Hymenoptera (divided as parasitoids and non-parasitoids) are similar to those of Coleoptera and Diptera. We used an insect material reared from logging residue wood for the comparison. Theoretically parasitoid Hymenoptera should be less specialised than Coleoptera and other host species as they belong to a higher trophic level. However, we found no such difference and even an opposite trend, that parasitoids were more specialised than beetles. Parasitoids had significantly more species in newly dead wood of fine diameter (1–4 cm, compared to coarse wood of 8–15 cm) compared to other groups. This is probably due to that many of them have bark beetles as hosts. The non-parasitoids were less specialised than the other groups and more confined to old wood (4–5 years), which is in line with that many of them are aculeate wasps building nests in emergence holes from other insects.Implications for insect conservationThe habitat requirements of Hymenoptera suggest that the conservation actions designed for the well known groups are also applicable for them. The parasitoids’ association to trivial substrates (fine wood) suggest a good supply of breeding habitat, whereas their high specialisation in combination with higher trophic level suggest they contain an even higher proportion of threatened species than Coleoptera. How this is traded off needs further studies.

Alter-azioni. Forme e temporalità della decomposizione nel progetto

The article explores the role of decay and its distinctive temporalities, highlighting the need to deal with change, randomness and disorder, to cultivate an attitude open to non-human other- ness, as part of an expanded concept of agency. The decomposition process of the dead tree as an access key to illustrate the importance of reasoning on co-becoming for the landscape project. A relationship that undoes the form, tears it apart, and infects it with otherness. Decomposing is a useful conceptual tool for thinking about biological diversity in the city and for changing the very vocabulary of the project, towards the concept of contamination. The article investigates the saproxylic insects, to discuss some methodologies aimed at interspecies practice, such as decentralizing human-centred ethics, adopting the animal point of view and hypothesizing the queering of the conventional canons of public space.

Combined stereomicroscope and SEM disentangle the fine morphology of the undescribed larva and puparium of the hoverfly Milesia crabroniformis (Fabricius, 1775) (Diptera: Syrphidae)

With over 80 species, Milesia Latreille, 1804 is a hoverfly genus (Diptera: Syrphidae) found in all continents except for Australia and the Antarctica. However, little is known about its life cycle and biology. The three Milesia species for which early stages are known have saproxylic larvae, suggesting that the larvae of all other Milesia species are also saproxylic. The early stages of the three Milesia species occurring in Europe are undescribed. Milesia crabroniformis (Fabricius, 1775), a mimic of the hornet Vespa crabro Linnaeus, 1758, is the largest hoverfly in Europe and is listed as Least Concern in the IUCN European Red List of Hoverflies. We here report the first early stages of Milesia ever found in Europe, describing them and their breeding sites. Larvae of M. crabroniformis were collected in water-filled tree holes of live chestnut trees (Castanea sativa Mill.) in Málaga, Southern Spain in 2020–2021. Various studies based on stereomicroscope and scanning electron microscopy (SEM) techniques have proven useful in diagnosing hoverfly early stages by observation of their fine morphology. Thus, these techniques were also used here to characterize the second (L2) and third (L3) stage larvae of M. crabroniformis, as well as the puparium. A Leica M205C binocular stereomicroscope and a Jeol JSM-ITH500HR SEM were used. The head skeleton and chaetotaxy of the L3 larva were described and illustrated. Adjustments to the diagnosis of the larvae of Milesia are proposed based on the number of hooks from the primary row of the main group of hooks. The new early stages are compared with those of other Milesia hoverflies, as well as with those of the sister group Spilomyia Meigen, 1803. The knowledge of the larval biology and breeding sites of saproxylic insects is useful for implementing forest management measures and species’ conservation programs.

Rapid assessment of feeding traces enables detection of drivers of saproxylic insects across spatial scales

Knowledge of habitat requirements of saproxylic insects and their response to habitat changes is critical for assessing the ecological impacts of forest management. Several studies have demonstrated a positive relationship of tree-species richness, deadwood volume, or structural diversity with saproxylic species diversity, while the relationship with the abundance of potential pest species have often been negative. A better understanding of which factors drive saproxylic insects’ occurrence is therefore essential for deriving urgently needed thresholds for key habitat conditions. We tested a rapid assessment method applicable at large scale based on recorded feeding galleries and boreholes assessed during the Austrian National Forest Inventory to investigate the drivers and habitat thresholds of different saproxylic insect families; i.e. Buprestidae, Cerambycidae, Curculionidae, Siricidae, at multiple spatial scales; i.e. at the object, forest stand and landscape level. We modelled the relative abundance of all insects and these families considering nineteen explanatory variables using ordinal logistic regression models. Key habitat characteristics were identified using recursive partitioning. Our results revealed complex interactions among influencing factors at different spatial scales. We showed that deadwood volume was of surprisingly little importance. Instead, individual tree characteristics were of major importance, demonstrating the value of resource quality and variability. The abundance of all saproxylic insect families increased with advancing decomposition, on trees taller than 18 m, and above a living stand volume of 41 m3ha−1. Aiming to guide forest management, not only forest type-specific, but tree species-specific deadwood management is needed, taking into account site-specific conditions, including temperature and precipitation. For assessing temporal trends in insect colonization and habitat dynamics as well as the effects of forest management, we propose a continuous monitoring of insect traces, including living but weakened trees. This will allow for further thresholds that are urgently needed for maintaining biological diversity in forest ecosystems in the face of climate change.

Urbanization filters woodpecker assemblages: Habitat specialization limits population abundance of dead wood dependent organisms in the urban landscape

Although urban landscapes are regarded as unsuitable for dead wood dependent organisms, some species, including woodpeckers, commonly occur in cities. As the availability of trees and dead wood resources is a primary dimension of the habitat-niche for most woodpeckers, we hypothesized that increasing habitat specialization (decreasing habitat-niche-volume) would limit species abundance within an urban landscape. We surveyed the woodpecker assemblage in the urban landscape, and for seven species we quantified the habitat-niche relying on four dimensions (the availability of trees, snags, fallen logs and dead tree branches). Then, we analysed the habitat preferences and habitat-niche partitioning of the woodpecker assemblage. For each species, we calculated the habitat-niche-volume and tested whether this trait correlated with species abundance in the urban landscape. Woodpeckers selected habitats with a high availability of either trees or dead wood (especially dead tree branches). The habitat-niches partially overlapped, but varied between species in terms of the availability of trees, dead tree branches, snags or fallen logs. The habitat-niche-volume varied among species and was positively associated with species abundance in the urban landscape. The regional abundance of species, body size and relative brain size did not affect the abundance of urban woodpecker populations. Our study highlights that urbanization filters woodpecker assemblages by limiting habitat-specialists and promoting habitat-generalists. We suggest that the alteration of woodpecker assemblages in the urban landscape may have a cascading effect on entire assemblages of dead wood dependent organisms, including cavity-nesters, saproxylic insects and wood-decomposing fungi. Urban development, which limits dead wood resources, is therefore a serious threat to biodiversity, whereas sustainable management of urban green spaces, e.g. the preservation of dead wood, may mitigate biodiversity loss.

Another one bites the plastics.

Old‐growth forests host a rich diversity of invertebrate assemblages. Among them, saproxylic insects play a fundamental role in the nutrient cycle and ecosystem functioning. In these environments, coevolution between insect and plants have reached a stable equilibrium over millions of years. These delicate ecosystems are threatened mainly by habitat loss and fragmentation, and to date, they have to face the new “plastic threat.” Plastics are widespread in all biomes and ecosystems accumulating throughout the years due to their low degradation rate. Once accumulated, large pieces of plastics can be degraded into smaller particles, the latter representing a great threat to biodiversity and ecosystem health, producing detrimental effects on biota. Since the effects of plastics on terrestrial systems remain largely unexplored, this study aimed at contributing to increasing the knowledge on the interaction between plastics and terrestrial biota. We put our emphasis on the novel and broad topic of plastic degradation by saproxylic beetle larvae, describing how they fragmented macroplastics into microplastics. To investigate whether saproxylic cetonid larvae could degrade expanded polystyrene, we performed an experiment. Thus, we put larvae collected in the field in an expanded polystyrene box. We observed that larvae dug in the thickness of the box fragmenting macroplastics into microplastics and producing a total of 3441 particles. Then, we removed the larvae from the EPS box and isolated them in glass jars filled with natural substrate. The substrate was checked for EPS microplastics previously ingested and now egested by larvae. Additionally, we pointed out that plastics remained attached to cetonid larvae setae, with a mean number of 30.7 ± 12.5 items. Although preliminary, our results highlighted that microplastics attached to saproxylic cetonid larvae might be transported into habitats and transferred along the food web. In conclusion, plastic pollution might affect vulnerable species and ecosystem services representing a risk also for human health.

Public LiDAR data are an important tool for the detection of saproxylic insect hotspots in Mediterranean forests and their connectivity

Light Detection and Ranging (LiDAR) is a remote sensing technique with multiple uses throughout scientific fields. It can also be used to transfer point data measured in the field to broader spatial scales, which might enable the evaluation of habitats over large areas and define biodiversity hotspots. Our study took place in Cabañeros National Park, which is situated in the Mediterranean, namely, central Spain, and its vegetation is dominated by forest and impenetrable scrubland. LiDAR was used to detect veteran trees as key elements for a highly diverse saproxylic community. The saproxylic beetle community inhabiting tree hollows was studied among different forest types and habitats to determine its preferences. We identified potential hotspots for the saproxylic beetle community of tree hollows both inside and outside of the park, as well as the connectivity of suitable habitat patches. This was based on the species response to the spatial partitioning of the landscape. We found that not all potentially suitable forest types hosted the same saproxylic diversity or similar species compositions. In addition, forest distribution and connectivity inside and outside of the park also varied highly among forest types and habitats, where the most diverse deciduous oak forest was also the least connected together with the riparian forest. The evergreen oak forest could act as a habitat linkage for most of the threatened and less mobile species in the park. However, the low connectivity of the most diverse forest types in the park surroundings can compromise the persistence of saproxylic diversity in the near future. We concluded that LiDAR data were an effective tool for estimating saproxylic beetle diversity distribution over large-scale areas in the context of landscapes with low accessibility. Additionally, this tool allowed us to identify the most threatened forest types and critical patches for connectivity persistence where management practices capable of accelerating tree veteranisation could help to increase adequate forest connectivity in the region.

Effects of the seasonal availability of freshly cut logs and tree species on the early response of saproxylic insects in boreal forest

Deadwood left on site after logging can be colonized by many saproxylic insects including xylophagous species that can damage the wood. This study aims to estimate the risks resulting from the storage of logs at the edge of balsam fir-white birch stands. We used taxonomic richness, as well as visitation and colonization rates of saproxylic insects to determine how their use of freshly cut logs varies with the seasonal availability of logs and the tree species. During the summer of 2019, balsam fir, black spruce, and paper birch logs were experimentally cut at three different periods and were placed in four harvested sites located in the Forêt Montmorency experimental forest in eastern Quebec, Canada. Visitation and colonization rates were assessed using trunk-window traps and log dissection, respectively. A total of 854 saproxylic insects belonging to 53 genera were captured over the three months of sampling. The logs were colonized by xylophagous species within one month after tree death. These xylophagous insects belonged mainly to the species Urocerus prob. albicornis, and Monochamus prob. scutellatus. Colonization rates of logs by Monochamus prob. scutellatus were higher from mid-July to mid-September than earlier during the season. These xylophagous species also responded to tree species, with higher abundance on conifers than on white birch both in terms of visitation and colonization rates. Furthermore, there was no evidence of colonization on paper birch. Our results suggest that a prompt harvesting of conifer logs between mid-July and mid-September on harvested sites will minimize damage to freshly cut logs.

Monitoring the abundance of saproxylic red-listed species in a managed beech forest by landsat temporal metrics

Rapid climate changes lead to an increase in forest disturbance, which in turn lead to growing concerns for biodiversity. While saproxylic beetles are relevant indicators for studying different aspects of biodiversity, most are smaller than 2 ​mm and difficult to sample. This, together with a high number of species and trophic roles, make their study remarkably challenging, time-consuming, and expensive. The Landsat mission provides data since 1984 and represents a powerful tool in this scenario. While we believe that remote sensing data cannot replace on-site sampling and analysis, in this study we aim to prove that the Landsat Time Series (TS) may support the identification of insects’ hotspots and consequently guide the selection of areas where to concentrate field analysis. With this aim, we constructed a Landsat-derived NDVI TS (1984–2020) and we summarised the NDVI trend over time by calculating eight Temporal Metrics (TMs) among which four resulted particularly successful in predicting the amount of saproxylic insects: (i) the slope of the regression line obtained by linear interpolating the NDVI values over time; (ii) the Root Mean Square Error (RMSE) between the regression line and the NDVI TS; (iii) the median , and the (iv) minimum values of the NDVI TS. The study area consists of four monitoring sectors in a Mediterranean-managed beech forest located in the Apennines (Molise, Italy), where 60 window flight traps for flying beetles were installed. First, the saproxylic beetle's biodiversities of monitoring sectors were quantified in terms of species richness and alpha-diversity. Second, the capability of TMs in predicting the richness of saproxylic beetles family and trophic categories was assessed in terms of Pearson's product-moment correlation. The alpha diversity and species richness analysis indicate dissimilarities across the four monitored sectors (Shannon and Simpson's index ranging between 0.67 to 2.31 and 0.69 to 0.88, respectively), with Landsat TS resulting in effective predictors for estimating saproxylic beetle richness. The strongest correlation was reached between the Monotomidae family and the RMSE temporal metric ( R ​= ​0.66). The mean absolute correlation ( r ) between the NDVI TMs and the saproxylic community was 0.46 for Monotomidae, 0.31 for Cerambycidae, and 0.25 for Curculionidae. Our results suggest that Landsat TS has important implications for studying saproxylic beetle distribution and, by helping the selection of monitoring areas, increasing the amount of information acquired while decreasing the effort required for field analysis.

Census of the longhorn beetles (Coleoptera, Cerambycidae and Vesperidae) of the Macau SAR, China.

An intensive census, extended over a period of approximately three and a half years, October 2017– May 2021, was conducted in the remaining green areas of the Macau SAR in order to provide an updated status of the biodiversity of longhorn beetles in this region. This insect group includes more than 36,000 species worldwide, subdivided into four families of mainly xylophagous or saproxylic insects, the Vesperidae, Oxypeltidae, Disteniidae, and Cerambycidae. They are of key importance in agricultural and forestry science, and are often used as an indicator of forest habitat health. A total of 52 species was recorded during this census, 2.6 times more than previously reported in the literature for this area. However, recorded abundances and frequency of occurrence for the various species were remarkably low, and of the 20 species previously reported for the region, some prominent ones remained unaccounted for. Among others, these include Batocera horsfieldii (Hope, 1839), Apriona rugicollis Chevrolat, 1852 [previously incorrectly reported as Apriona germarii (Hope, 1831)], Aristobia reticulator (Fabricius, 1781) [previously reported as Aristobia testudo (Voet, 1778)] and Imantocera penicillata (Hope, 1831). It is hypothesised that this may be related to the ongoing manipulation of the natural vegetation of the Macau SAR, which is rapidly being converted to plantations, city parks, and gardens. In particular, dead or dying trees and lower tree branches are systematically removed in order to improve the aesthetic appearance of these green areas. However, this process is also depriving xylophagous and saproxylic species of their essential habitats.

Saproxylic fly diversity in a Costa Rican forest mosaic

ABSTRACT Dead wood is a microcosm of biological diversity. Saproxylic insect diversity at the global level is immense, with estimates that up to one third of forest dwelling species rely on moribund or dead wood at some point in their life cycle. Most studies on saproxylic insects have focused on taxa such as beetles, or on areas like the northern temperate regions. This paper presents the first assessment of the diversity of tropical saproxylic Diptera, from the Osa Peninsula of Costa Rica. Forty-one trees representing nine species and six plant families were sampled in a rearing experiment designed to study saproxylic beetles. In total, 272 individuals attributable to 18 families of Diptera were reared as bycatch. Low abundance and species richness of flies was observed overall. A majority of taxa were in saprophagous and mycophagous larval feeding guilds, followed by predators. Host associations, successional stage, and stratum preferences are estimated for the more abundant species. The results support previous findings regarding saproxylic Diptera and their association with moist wood and secondary forests. Interesting trends and noteworthy reared taxa are discussed.