Termites as bioindicators of habitat quality in the caatinga, Brazil: is there agreement between structural habitat variables and the sampled assemblages?

The composition of termite assemblages was analyzed in three caatinga sites of the Esta??o Ecológica do Seridó, located in the municipality of Serra Negra do Norte, in the state of Rio Grande do Norte, Brazil. These sites have been subjected to selective logging, and cleared for pasture and farming. A standardized sampling protocol for termite assemblages (30h/person/site) was conducted between September 2007 and February 2009. At each site we measured environmental variables, such as soil pH and organic matter, necromass stock, vegetation height, stem diameter at ankle height (DAH) and the largest and the smallest crown width. Ten species of termites, belonging to eight genera and three families, were found at the three experimental sites. Four feeding groups were sampled: wood-feeders, soil-feeders, wood-soil interface feeders and leaf-feeders. The wood-feeders were dominant in number of species and number of encounters at all sites. In general, the sites were not significantly different in relation to the environmental variables measured. The same pattern was observed for termite assemblages, where no significant differences in species richness, relative abundance and taxonomic and functional composition were observed between the three sites. The agreement between composition of assemblages and environmental variables reinforces the potential of termites as biological indicators of habitat quality.     

Sharing of termites (Blattodea: Isoptera) between sugarcane matrices and Atlantic Forest fragments in Northeast Brazil

The Atlantic Forest of South America is one of the most degraded tropical forests and the cultivation of sugarcane is considered one of the main causes. In humid forests termites stand out with regard to their abundance and functional importance. The present study aimed to compare termite assemblages of fragments of the Atlantic Forest with that of the sugarcane matrices that surround them. Collections were performed in two sugarcane plantations in Northeast Brazil. In each plantation a fragment of Atlantic Forest and an adjacent sugarcane field were sampled using a standardized termite sampling protocol. A total of 39 species and 302 encounters were recorded. Species richness, relative abundance and composition differed significantly between forests and the matrices, with the presence of exclusive species in each environment—25 in the forests and seven in the matrices. Soil feeding species of the subfamily Apicotermitinae and species of open areas were found in the matrices. There was a marked difference between the assemblages of the matrices, possibly due to soil characteristics. The majority of the species found in the matrices do not cause damage to the crop, but instead act in the processes of soil decomposition and formation, thereby contributing to increased productivity.     

Predatory abilities favour the success of the invasive ant Pheidole megacephala in an introduced area

Abstract:  The invasive African big-headed ant, Pheidole megacephala , is a dominant species in the many areas it has invaded. We examined whether one potential reason for its ecological success might be its predatory efficiency. We compared the density of termite nests in an area of Mexico invaded by P. megacephala with an adjacent area where P. megacephala is not present. We also compared the success of P. megacephala in preying on termites with that of 13 native ant species. We found that termite nest density was significantly lower in areas invaded by P. megacephala (0.33 vs. 1.05 nests per 30 m transect). In field trials, we established that P. megacephala workers were significantly more successful at capturing termite workers from termite nest fragments than even the most successful native ant species, Dorymyrmex pyramicus . For both P. megacephala and D. pyramicus , single scouts could trigger the mass recruitment of nestmates, but P. megacephala was able to recruit greater numbers of nestmates. Combined with their aggressiveness towards other ant species, their highly efficient predatory capacities help explain the ecological success of P. megacephala and demonstrate how it can be a major threat to invertebrate biodiversity in the areas it invades.     

Does selective logging change ground‐dwelling beetle assemblages in a subtropical broad‐leafed forest of China?

Selective logging with natural regeneration is advocated as a near‐to‐nature strategy and has been implemented in many forested systems during the last decades. However, the efficiency of such practices for the maintenance of forest species are poorly understood. We compared the species richness, abundance and composition of ground‐dwelling beetles between selectively logged and unlogged forests to evaluate the possible effects of selective logging in a subtropical broad‐leafed forest in southeastern China. Using pitfall traps, beetles were sampled in two naturally regenerating stands after clearcuts (ca. 50 years old, stem‐exclusion stage: selectively logged 20 years ago) and two mature stands (> 80 years old, understory re‐initiation stage: selectively logged 50 years ago) during 2009 and 2010. Overall, selective logging had no significant effects on total beetle richness and abundance, but saproxylic species group and some abundant forest species significantly decreased in abundance in selectively logged plots compared with unlogged plots in mature stands. Beetle assemblages showed significant differences between selectively logged and unlogged plots in mature stands. Some environmental characteristics associated with selective logging (e.g., logging strategy, stand age, and cover of shrub and moss layers) were the most important variables explaining beetle assemblage structure. Our results conclude that selective logging has no significant impacts on overall richness and abundance of ground‐dwelling beetles. However, the negative effects of selective logging on saproxylic species group and some unlogged forest specialists highlight the need for large intact forested areas for sustaining the existence of forest specialist beetles.     

Bait matrix for delivery of chitin synthesis inhibitors to the formosan subterranean termite (Isoptera: Rhinotermitidae)

The efficacy of three chitin synthesis inhibitors, diflubenzuron, hexaflumuron, and chlorfluazuron, incorporated into a novel bait matrix to kill the Formosan subterranean termite, Coptotermes formosanus Shiraki, was evaluated in the laboratory. The bait matrix was significantly preferred by C. formosanus over southern yellow pine wood in a two-choice feeding test. Bait formulations containing 250 ppm of the three chitin synthesis inhibitors were presented to termite nests with 2,500 individuals (80% workers and 20% soldiers) in the presence of alternative food sources consisting of cardboard and southern yellow pine, Pinus taeda L., wood. None of the bait formulations were significantly repellent or feeding deterrent to the termite workers evidenced by the lack of full consumption of alternative food sources. All nests presented with the bait formulations died within 9 wk, whereas the control nests (bait with no chitin synthesis inhibitors) remained alive 6 mo after the end of the study. No significant differences in consumption were observed among the chitin synthesis inhibitor treatments. Importance of this study for the improvement of current bait technology is discussed.     

Gap felling as a forest harvesting method in boreal forests: responses of carabid beetles (Coleoptera, Carabidae)

In order to study the ecological effects of logging combined with mechanical soil preparation, we sampled carabid beetles with pitfall trapping in nine spruce-dominated stands in central Finland in 1995–1998. Three of the stands were left intact as controls. Three 1600-m² openings per stand were logged in the winter 1995–1996 into six stands. In three of these stands, light soil preparation was applied. Logging affected the species assemblages, but soil preparation per se had no clear effects. Open-habitat species increased in abundance in the openings one year after logging, but catches of generalist species in the different treatments did not differ from each other. A forest species, Calathus micropterus , was least abundant in the prepared openings. The amounts of logging residue, exposed mineral soil and aggregated humus, as well as the abundance of red wood ants, significantly explained variation in carabid assemblages.     

Termite diversity along a land use intensification gradient in a semi-arid savanna

Disturbance, particularly agricultural expansion is one of the major threats to the biodiversity and ecological functions of tropical and sub-tropical ecosystems. In this regard, we examined changes in the species richness, abundance, and diversity of termites across different disturbance treatments in a sub-tropical semi-arid savanna in south eastern Zimbabwe. Nine transects (100?×?2 m) representing three habitat disturbance treatments (primary woodland; grazing area; agricultural field) were sampled for termites using a rapid biodiversity assessment protocol. Termites were more abundant and species-rich in primary woodland and grazing area than in the agricultural field. Twelve termite species from three sub-families were present, with Microtermes sp. constituting 35% of the identified termite species. Termite feeding group structure differed significantly among land-use types, and of all termites present, wood-feeding termites were the most abundant while soil-feeders were rare in the agricultural field. In conclusion the observed pattern in termite species richness and relative abundance indicates that termites are very resilient to natural disturbance and might actually benefit from some natural disturbances like they did in the grazing area of this study, but they are not resilient to extreme anthropogenic disturbance. Although there was no notable difference in termite species richness and relative abundance between agricultural field and primary woodland, the pattern observed across the three sites may be potential support for the IDH suggesting that intermediate levels of physical disturbance intensity influence the structure and functioning of termite assemblages in semi-arid savanna.     

Forest recovery on abandoned logging roads in a tropical montane rain forest of Hainan Island,China

In this study we report the work in recovering forest stands on Hainan Island in South China; we compared the community composition, structure, and plant functional traits (seed mass and wood density) on three positions of abandoned logging roads: road track (RT), road up-slope edge (UE) and road down-slope edge (DE). The results showed that species richness, stem abundance, basal area, stem size, and canopy height were all lowest on the RT among the three road positions. Species richness and abundance of midstorey and canopy trees were higher on the UE than on the DE. The mean stem size was higher on the DE than the UE, but no significant difference existed in canopy height on the two road edges. The different road positions were characterized by varied species assemblages. Indicator species analysis further indicated that 76.9%, 15.4% and 7.7% of the species showed affinity to UE, DE, and RT, respectively. The RT had more small-seeds but less soft-wood trees than the two road edges. The UE and DE had no significant difference in tree seed class distribution. Compared with the DE, however, the UE had a higher and lower proportion of hard wood in terms of species richness and stem abundance, respectively. Our results indicated that the composition and structure of stands on the abandoned logging roads had significantly changed in comparison with the stands around it.     

Evolution of termite functional diversity: analysis and synthesis of local ecological and regional influences on local species richness

Aim To (1) describe termite functional diversity patterns across five tropical regions using local species richness sampling of standardized areas of habitat; (2) assess the relative importance of environmental factors operating at different spatial and temporal scales in influencing variation in species representation within feeding groups and functional taxonomic groups across the tropics; (3) achieve a synthesis to explain the observed patterns of convergence and divergence in termite functional diversity that draws on termite ecological and biogeographical evidence to‐date, as well as the latest evidence for the evolutionary and distributional history of tropical rain forests. Location Pantropical. Methods A pantropical termite species richness data set was obtained through sampling of eighty‐seven standardized local termite diversity transects from twenty‐nine locations across five tropical regions. Local‐scale, intermediate‐scale and large‐scale environmental data were collected for each transect. Standardized termite assemblage and environmental data were analysed at the levels of whole assemblages and feeding groups (using components of variance analysis) and at the level of functional taxonomic groups (using correspondence analysis and canonical correspondence analysis). Results Overall species richness of local assemblages showed a greater component of variation attributable to local habitat disturbance level than to region. However, an analysis accounting for species richness across termite feeding groups indicated a much larger component of variation attributable to region. Mean local assemblage body size also showed the greater overall significance of region compared with habitat type in influencing variation. Ordination of functional taxonomic group data revealed a primary gradient of variation corresponding to rank order of species richness within sites and to mean local species richness within regions. The latter was in the order: Africa > south America > south‐east Asia > Madagascar > Australia. This primary gradient of species richness decrease can be explained by a decrease in species richness of less dispersive functional taxonomic groups feeding on more humified food substrates such as soil. Hence, the transects from more depauperate sites/regions were dominated by more dispersive functional taxonomic groups feeding on less humified food substrates such as dead wood. Direct gradient analysis indicated that ‘region’ and other large‐scale factors were the most important in explaining patterns of local termite functional diversity followed by intermediate‐scale geographical and site variables and, finally, local‐scale ecological variables. Synthesis and main conclusions Within regions, centres of termite functional diversity lie in lowland equatorial closed canopy tropical forests. Soil feeding termite evolution further down food substrate humification gradients is therefore more likely to have depended on the long‐term presence of this habitat. Known ecological and energetic constraints upon contemporary soil feeders lend support for this hypothesis. We propose further that the anomalous distribution of termite soil feeder species richness is partly explained by their generally very poor dispersal abilities across oceans. Evolution, radiation and dispersal of soil feeder diversity appears to have been largely restricted to what are now the African and south American regions. The inter‐regional differences in contemporary local patterns of termite species richness revealed by the global data set point to the possibility of large differences in consequent ecosystem processes in apparently similar habitats on different continents.     

The recolonization of the Krakatau islands by termites (Isoptera), and their biogeographical origins

The termite assemblages of the Krakatau islands and five sites in Sumatra and Java were investigated, using a standardized transect sampling method. Five species were found on the Krakatau islands that have not been collected there before. The total number of termites recorded on the islands since the 1883 volcanic eruption is now twelve species, all of which are wood feeders. No termites nesting in or feeding on the soil were found on the Krakataus, suggesting that rafting in wood is the primary method by which the termites recolonized the islands.     

Factors influencing the appearance of spider (Araneae) and beetle (Coleoptera) assemblages in nests of great reed warbler Acrocephalus arundinaceus

The appearance of spider (Araneae) and beetle (Coleoptera) assemblages found in nests of great reed warbler Acrocephalus arundinaceus was studied, firstly to investigate breeding success and the amount of precipitation as potential factors which might affect the abundance and species richness of both groups. In addition, we compared the diversity of spider and beetle assemblages between nests found in different reed habitats, and considered the position of nests (above water or dry ground). In this study we selected five different randomly chosen reed habitats: two mining ponds, two small canals and one large canal. Great Reed Warbler nests were collected either shortly after fledging, or after the clutch had failed. Altogether, 12 species of spider and 19 species of beetle were collected. In both groups there was no significant difference in abundance between successful, lost and cuckoo-parasitized nests; however, there was a significant difference in species richness between the three nest categories in spider assemblages, which was not the case in beetle assemblages. The amount of precipitation did not affect beetle or spider abundance; only the species richness of spiders showed significant growth. Furthermore, we found no significant relationship between vegetation cover and the species richness and abundance of spiders and beetles. The diversity of both groups differed significantly according to reed habitat: beetle assemblages were most diverse by the large canal and spiders at the mining ponds.     

Nesting ecology of stingless bees and potential threats to their survival within selected landscapes in the northern Volta region of Ghana

Stingless bees are key insects in the tropics, both as pollinators of crops and as contributors to the maintenance of floral diversity through pollination of wild plants. This study investigated the nesting ecology and threats to three stingless bee species: Meliponula bocandei (Spinola), Meliponula ferruginea (Lepeletier) and Dactylurina staudingeri (Gribodo) in three landscapes characterized as forest with logging and wild honey hunting; farmlands that experience annual wild fires and a national park. The study was carried out in July 2011 and February 2012. A total of 93 stingless bee nests were found in 48 ha (density 1.9 nests per ha), 81% in tree cavities and 19% in deserted termite mounds and in the ground. M. ferruginea was the only species using deserted termite mounds (seventeen nests) and in the ground (1 nest). Although tree size (diameter at breast height, DBH >15 cm) and density of large tree were important for nest site selection, there was no influence of tree species. M. bocandei may be restricted in choice of nest site in farmland areas by the absence of trees. Reduced availability of trees in agricultural landscape together with bush burning and wild honey collecting is the main threats to stingless bees survival and abundance which need to be addressed for their successful conservation in Ghana.     

Avian frugivore assemblages on Celtis gomphophylla,Baker, in Budongo Forest Reserve,Uganda

The relationship between selective logging and avian frugivores feeding on Celtis gomphophylla was examined in Budongo Forest Reserve, from June to July 2005, using scan sampling. Abundance and species richness of avian frugivores were compared between two compartments (N3 and W22 last logged in 1952 and 1997 respectively). Two 1‐ha plots were established in each compartment from which two C. gomphophylla trees selected for observation. A total of 203 avian frugivores comprising 17 species, visited the eight C. gomphophylla trees. Avian frugivore abundance and richness were significantly higher in N3 than W22 (χ² = 5.83, χ² = 0.03, P < 0.05). Fischer's alpha diversity index also indicated a higher avian frugivore (frugivory?) in N3 than that in W22. The Sorensen's similarity index showed that species composition between the two compartments was moderately similar. The diversity of forest specialists and generalists was not significantly different in the two compartments (F = 0.3451, P = 0.082 and F = 0.368, P = 0.553). Our results stress the significance of logging intensity on avian feeding guilds and confirm that forests which have had enough recovery time are better habitats for avian frugivore assemblages.     

Behavioral Interactions Between <Emphasis Type="Italic">Aphaenogaster rudis</Emphasis> (Hymenoptera: Formicidae) and <Emphasis Type="Italic">Reticulitermes flavipes</Emphasis> (Isoptera: Rhinotermitidae): The Importance of Physical Barriers

Predation pressure from ants is a major driving force in the adaptive evolution of termite defense strategies and termites have evolved elaborate chemical and physical defenses to protect themselves against ants. We examined predator–prey interactions between the woodland ant, Aphaenogaster rudis (Emery) and the eastern subterranean termite, Reticulitermes flavipes (Kollar), two sympatric species widely distributed throughout deciduous forests in eastern North America. To examine the behavioral interactions between A. rudis and R. flavipes we used a series of laboratory behavioral assays and predation experiments where A. rudis and R. flavipes could interact individually or in groups. One-on-one aggression tests revealed that R. flavipes are vulnerable to predation by A. rudis when individual termite workers or soldiers are exposed to ant attacks in open dishes and 100% of termite workers and soldiers died, even though the soldiers were significantly more aggressive towards the ants. The results of predation experiments where larger ant and termite colony fragments interacted provide experimental evidence for the importance of physical barriers for termite colony defense. In experiments where the termites nested within artificial nests (sand-filled containers), A. rudis was aggressive at invading termite nests and inflicted 100% mortality on the termites. In contrast, termite mortality was comparable to controls when termite colonies nested in natural nests comprised of wood blocks. Our results highlight the importance of physical barriers in termite colony defense and suggest that under natural field conditions termites may be less susceptible to attacks by ants when they nest in solid wood, which may offer more structural protection than sand alone.     

Nests of Augochlora (A.) esox in Bromeliads,a Previously Unknown Site for Sweat Bees (Hymenoptera: Halictidae)

Five nests of Augochlora (Augochlora) esox (Vachal, 1911) were detected in the rosettes of bromeliads (Aechmaea nudicaulis and A. lindenii) on the island of Santa Catarina, Brazil. Two of the nests were constructed after manipulation of bromeliads as trap nests. Cells were built in the central funnel filled with moist black humus in a scattered way without a detectable pattern. One founding female and all brood stages from eggs to pupae as well as male and female imagines were found in the nests which contained between 3–16 cells each. The uppermost cells contained the youngest larvae whereas pupae and young imagines were found at the bottoms of the nests. Pollen carried by the provisioning female and present in provisions of two nests originated from 18 plant species, in particular Asteraceae and Melastomataceae. Nest architecture is compared to that of congeners, and the use of bromeliads as nest sites for bees is discussed.     

Diet is the primary determinant of bacterial community structure in the guts of higher termites

The gut microbiota of termites plays critical roles in the symbiotic digestion of lignocellulose. While phylogenetically ‘lower termites’ are characterized by a unique association with cellulolytic flagellates, higher termites (family Termitidae) harbour exclusively prokaryotic communities in their dilated hindguts. Unlike the more primitive termite families, which primarily feed on wood, they have adapted to a variety of lignocellulosic food sources in different stages of humification, ranging from sound wood to soil organic matter. In this study, we comparatively analysed representatives of different taxonomic lineages and feeding groups of higher termites to identify the major drivers of bacterial community structure in the termite gut, using amplicon libraries of 16S rRNA genes from 18 species of higher termites. In all analyses, the wood‐feeding species were clearly separated from humus and soil feeders, irrespective of their taxonomic affiliation, offering compelling evidence that diet is the primary determinant of bacterial community structure. Within each diet group, however, gut communities of termites from the same subfamily were more similar than those of distantly related species. A highly resolved classification using a curated reference database revealed only few genus‐level taxa whose distribution patterns indicated specificity for certain host lineages, limiting any possible cospeciation between the gut microbiota and host to short evolutionary timescales. Rather, the observed patterns in the host‐specific distribution of the bacterial lineages in termite guts are best explained by diet‐related differences in the availability of microhabitats and functional niches.     

Latitudinal Variation in Termite Species Richness and Abundance along the Brazilian Atlantic Forest Hotspot

In this study, we investigated the termites of the Brazilian Atlantic Forest, one of the most threatened biodiversity hotspots in the world, in regularly spaced sites from 7° S to 27° S latitude. To our knowledge, this is the only report of a latitudinal survey of termites at species level performed with a standardized sampling protocol. We evaluate termite diversity and abundance, and describe patterns of species composition based on feeding groups along the latitudinal gradient. We also describe the relative contribution of environmental variables to explain diversity patterns. Termite assemblages were investigated by standardized surveys at 15 Atlantic Forest sites, on six transects divided into five sections of 10 m², with 30 sections per site (or 300 m²/site), which were investigated by one trained person for one hour. Observed species richness and abundance were negatively correlated with latitude. The influence of latitude was explained mainly by variables related to temperature, precipitation and ambient energy (potential evapotranspiration). Our results also suggest that temperature exerts a greater constraint on Atlantic Forest termites than productivity, because ambient productivity increases with latitude in this forest but termite diversity decreases. Termite species richness in the Atlantic Forest showed a different pattern than those described for other organisms, increasing in diversity where the coastal‐forest strip narrows. Overall, our results indicate comparatively high termite species richness at northeastern sites and a significant impoverishment of termite assemblages in the southeastern and southern regions of the Atlantic Forest.     

Predator-mediated interactions between and within guilds of nesting songbirds: experimental and observational evidence

ABSTRACT Apparent competition (i.e., a mutually negative indient rect interaction between prey species through shared predation) arises when predator abundance or foraging effort increases with spetotal prey availability. We review and formalize several patch-use models from which we derive predictions for how the degree of coupling (from the predators' perspective) between nesting guilds (defined as species nesting within a vegetation stratum) affects the outcome of shared predation. We then determine which model best applies to nest predation on woodland songbirds and artificial nests by a natural population of raccoons. Using artificial nests, we showed that increasing the density of nests placed either in shrubs or on the ground increased overall predation (i.e., proportion of nests) on both types. We also tested for apparent competition between American robin and wood thrush, two coexisting woodland songbirds that commonly nest within the shrub stratum. Nest predation increased for wood thrushes but not robins as the combined density of robin and thrush nests within two individual substrate types, Lonicera and Rhamnus, increased. Thus, we documented apparent competition both within and among nesting guilds. We discuss the possible relevance of this interaction in determining species diversity, particularly in the light of increasing generalist nest predators through anthropogenically driven changes in human-altered landscapes.     

Short‐term changes in the structure of termite assemblages associated with slash‐and‐burn agriculture in Côte d'Ivoire

Termites are major decomposers in tropical regions and play critical roles in many soil‐related processes. Studies conducted in Asia and the Neotropics suggest that habitat modification can strongly affect termite assemblages, but data on termite communities from forests in Africa, especially West Africa, are scarce. Here, we measured the short‐term impact of slash‐and‐burn agriculture on termite assemblages in an agricultural region of central Côte d'Ivoire. We assessed termite diversity and relative abundance in four habitat types: secondary forest, cleared forest, burned forest, and crop fields. The secondary forest had higher species richness compared with the other habitats, but all habitat types had similar assemblage structures. Fungus‐growing termites were the most abundant feeding group in all habitats. Soil feeders were most abundant in secondary forest, intermediately abundant in cleared and burned forests, and almost entirely absent in crop fields. Wood‐feeding species showed clear responses to burning; their abundances decreased after fire. We conclude that slash‐and‐burn agriculture does not appear to severely erode the diversity of termite assemblages. This could be due to the dominance of ecologically versatile fungus growers or to the relatively long time between clearing and burning. However, forest clearing negatively affects soil feeders, with the Apicotermitinae most affected by canopy loss.