Phylogeography illuminates maternal origins of exotic Coptotermes gestroi (Isoptera: Rhinotermitidae)

Evolutionary history of Nasutitermes kemneri (Termitidae, Nasutitermitinae), a termite from the South American diagonal of open formations

Little is known about the phylogeography of termites in the Neotropical region. Here, we explored the genetic patterns and phylogeographical processes in the evolutionary history of Nasutitermes kemneri, an endemic termite of the South American diagonal of open formations (DOF) formed by the Chaco, Cerrado, and Caatinga phytogeographic domains. We sampled 60 individuals across the three domains of the DOF, and using the mitochondrial genes 16S, COI, and COII, as well as the nuclear gene ITS, evaluated the genetic diversity and divergence time of the populations, along with their genetic structure. The results show a strong genetic and spatial structure within the samples, evidencing the existence of two well-differentiated genetic groups: the Northeastern and the Southwestern populations, which diverged about 2.5 Mya, during the Pliocene-Pleistocene boundary. The Northeastern population, which encompasses Caatinga and northern portions of Cerrado, has an intricate structure and seems to have suffered repetitive retraction-expansion events due to climactic fluctuations during the Quaternary. The Southwestern population, which ranges from central-south Cerrado to the northeast peripherical portions of the Chaco, displays a star-shaped haplotype structure, indicating that this region may have acted as a refugia during interglacial periods.

Comparative reproductive biology of pre-, imaginal, and neotenic castes of the Asian termite Coptotermes gestroi (Blattaria, Isoptera, Rhinotermitidae)

The Asian subterranean termite Coptotermes gestroi is a worldwide structural pest, although its reproductive biology has been poorly investigated due to a cryptic habit and occurrence of polycalic nests. In this study, we investigated ovarian development and oogenesis in different-aged females of C. gestroi: fourth-instar nymphs, non-functional neotenics, alates, and functional queens. We show that the ovaries develop gradually according to their age and functionality, as younger individuals possess immature oocytes, whereas alates and functional queens always undergo vitellogenesis. Oocytes were classified into previtellogenic (stages I, II, and III) or vitellogenic (stages IV, V, and VI). Ovary development varied among non-functional neotenics, and a rapid differentiation and/or the presence of primary reproductives are believed to influence such a maturation. Immature oocyte stages were shared between fourth-instar nymphs and neotenics. These characteristics, together with other neotenic features (wing buds, body pigmentation, and eye color), should be evaluated in detail aiming to clarify which nymphal instars differentiate into secondary reproductives. Oogenesis was not uniform among alate females, and cross-sectional area of terminal oocytes was significantly smaller in alates when compared to functional queens, suggesting different degrees of maturation in swarming individuals. Functional queens always had mature terminal oocytes (stage VI). Ovariole number and oocyte maturation in C. gestroi relies on several factors and may therefore differ among individuals of the same caste. Future studies should take into account these reproductive features to evaluate how they impact colony development.

Historical and future climate change fosters expansion of Australian harvester termites, Drepanotermes

Past evolutionary adaptations to Australia's aridification can help us to understand the potential responses of species in the face of global climate change. Here, we focus on the Australian-endemic genus Drepanotermes, also known as Australian harvester termites, which are mainly found in semiarid and arid regions of Australia. We used species delineation, phylogenetic inference, and ancestral state reconstruction to investigate the evolution of mound-building in Drepanotermes and in relation to reconstructed past climatic conditions. Our findings suggest that mound-building evolved several times independently in Drepanotermes, apparently facilitating expansions into tropical and mesic regions of Australia. The phylogenetic signal of bioclimatic variables, especially limiting environmental factors (e.g., precipitation of the warmest quarter), suggests that the climate exerts a strong selective pressure. Finally, we used environmental niche modeling to predict the present and future habitat suitability for eight Drepanotermes species. Abiotic factors such as annual temperature contributed disproportionately to calibrations, while the inclusion of biotic factors such as predators and vegetation cover improved ecological niche models in some species. A comparison between present and future habitat suitability under two different emission scenarios revealed continued suitability of current ranges as well as substantial habitat gains for most studied species. Human-mediated climate change occurs more quickly than these termites can disperse into newly suitable habitat; however, their role in stabilizing arid ecosystems may allow them to mitigate effects on some other organisms at a local level.

Phylogeography of Nasutitermes ephratae (Termitidae: Nasutitermitinae) in neotropical region

The neotropical region ranks third in the number of termites and includes five different families. Of these, Termitidae is the most diverse and includes the species Nasutitermes ephratae, which is widespread in the neotropics. To date, only one study has been published about phylogeography in neotropical termites (N. corniger). Here, we explored the population genetic patterns of N. ephratae and also evaluated the phylogeographical processes involved in the evolutionary history of the species. We used the mitochondrial genes 16S rRNA and COII as molecular markers: these were sequenced for 128 samples of N. ephratae. We estimated the genetic diversity and divergence time as well as the demography and genetic structure. We also performed an ancestral area reconstruction and a haplotype network. The results showed high genetic variability, recent demographic expansion, and strong genetic structure. A dispersal route for the species, that occurred in both directions between South and Central America, was inferred. The results emphasize a temporary separation between the South and Central America populations that affected the origin of the current Central America populations. These populations were formed from different phylogeographic histories.

Area-Wide Elimination of Subterranean Termite Colonies Using a Novaluron Bait

We investigated the use of termite baiting, a proven system of targeted colony elimination, in an overall area-wide control strategy against subterranean termites. At two field sites, we used microsatellite markers to estimate the total number of Reticulitermes colonies, their spatial partitioning, and breeding structure. Termite pressure was recorded for two years before and after the introduction of Trelona® (active ingredient novaluron) to a large area of one of the sites. Roughly 70% of the colonies in the treatment site that were present at the time of baiting were not found in the site within two months after the introduction of novaluron. Feeding activity of the remaining colonies subsequently ceased over time and new invading colonies were unable to establish within this site. Our study provides novel field data on the efficacy of novaluron in colony elimination of Reticulitermes flavipes, as well as evidence that an area-wide baiting program is feasible to maintain a termite-free area within its native range.

High-Throughput Cultivation for the Selective Isolation of Acidobacteria From Termite Nests

Microbial communities in the immediate environment of socialized invertebrates can help to suppress pathogens, in part by synthesizing bioactive natural products. Here we characterized the core microbiomes of three termite species (genus Coptotermes) and their nest material to gain more insight into the diversity of termite-associated bacteria. Sampling a healthy termite colony over time implicated a consolidated and highly stable microbiome, pointing toward the fact that beneficial bacterial phyla play a major role in termite fitness. In contrast, there was a significant shift in the composition of the core microbiome in one nest during a fungal infection, affecting the abundance of well-characterized Streptomyces species (phylum Actinobacteria) as well as less-studied bacterial phyla such as Acidobacteria. High-throughput cultivation in microplates was implemented to isolate and identify these less-studied bacterial phylogenetic group. Amplicon sequencing confirmed that our method maintained the bacterial diversity of the environmental samples, enabling the isolation of novel Acidobacteriaceae and expanding the list of cultivated species to include two strains that may define new species within the genera Terracidiphilus and Acidobacterium.

Mitochondrial Genetic Diversity of the Freshwater Snail Melanoides tuberculata

According to geological history, Peninsular Malaysia and Borneo formed at different times and were once connected during Quaternary glaciations. To determine how this history has influenced phylogeography, our study examined the population genetic structure of the tropical freshwater gastropod Melanoides tuberculata across Peninsular Malaysia and Borneo using the sequences from mitochondrial DNA 16S rRNA and cytochrome oxidase subunit I genes (1168 bp). In total, 104 specimens were collected from seventeen populations. All mtDNA haplotypes were identified as belonging to two highly divergent lineages, and these lineages were almost allopatric in their distributions. Our study found that the freshwater fauna in Malaysia might be divided into four regions: northeast Peninsular Malaysia, northwest Peninsular Malaysia, south Peninsular Malaysia, and Borneo. The phylogeography of M. tuberculata in Malaysia was shaped by the landforms of Peninsular Malaysia and by the paleo-river systems in the Sunda continental shelf. In addition, our study found that these two lineages in Malaysia have invaded the globe. These results suggest that Malaysia is located in important shipping lanes throughout the world, and the populations of M. tuberculate might be widely distributed throughout the world by shipping.

Efeitos de isolados do fungo Isaria (Persoon) sobre o cupim subterrâneo Coptotermes gestroi (Wasmann) (Isoptera: Rhinotermitidae)

Coptotermes gestroi (Wasmann) é considerada uma das espécies mais destrutivas de cupins subterrâneos, por causar danos a edificações, à arborização urbana e a culturas. Uma alternativa para o controle desse inseto pode ser o uso de agentes biocontroladores, como os fungos entomopatogênicos. Isaria (Persoon) tem sido indicado no controle de térmitas subterrâneos, inclusive do gênero Coptotermes. Dessa forma, o presente trabalho teve como objetivo selecionar isolados de Isaria patogênicos ao cupim C. gestroi. Os insetos pulverizados com suspensões fúngicas de I. farinosa, I. fumosorosea e I. javanica foram avaliados diariamente para a determinação da mortalidade. Todos os isolados foram patogênicos, ocasionando mortalidade acima de 70%, e virulentos, apresentando uma sobrevivência média de 2,0 a 3,9 dias. Contudo, os isolados ESALQ-1205 de I. farinosa, ESALQ-1296 de I. fumosorosea e os isolados URM-4995 e URM-4993 de I. javanica mostraram-se mais virulentos. A CL50estimada para os isolados ESALQ-1205 de I. farinosa, URM-4995 de I. javanica e ESALQ-1296 de I. fumosorosea resultou em valores de 3,7 x 105, 1,4 x 106e 2,7 x 106conídios mL-1, respectivamente. Tais resultados confirmam a eficiência dos isolados testados sobre os operários de C. gestroi. No entanto, novos estudos são necessários para verificar a melhor forma de utilização, bem como a sua efetividade em campo.

Haplotype-habitat associations of Coptotermes gestroi (Termitoidae: Rhinotermitidae) from mitochondrial DNA genes

Coptotermes gestroi (Wasmann) or the Asian subterranean termite is a serious structural pest in urban settlements in Southeast Asia that has been introduced to other parts of the world through human commerce. Although mitochondrial DNA markers were previously used to shed light on the dispersal history of the Asian subterranean termite, there were limited attempts to analyze or include populations of the termite found in the wild in Southeast Asia. In this study, we analyzed the 16S ribosomal RNA (16S rRNA) and cytochrome c oxidase subunit 1 (cox1) genes of Asian subterranean termite colonies found in mangrove swamps, beach forests, plantations, and buildings in semi-urban and urban areas to determine the relationship between colonies found in the wild and the urban habitat, and to investigate the possibility of different ecotypes of the termite in Peninsular Malaysia. Our findings show that the 16S rRNA haplotypes recovered from this study clustered into eastern, western, and southern populations of the termite, while the cox1 haplotypes were often specific to an area or site. The 16S rRNA and cox1 genes or haplotypes showed that the most abundant haplotype occupied a wide range of environments or habitats. In addition, the cox1 tree showed evidence of historical biogeography where basal haplotypes inhabited a wide range of habitats, while apical haplotypes were restricted to mangrove swamps and beach forests. Information on the haplotype-habitat association of C. gestroi will enable the prediction of habitats that may harbor or be at risk of invasion in areas where they have been introduced.

Deciphering the synergism of endogenous glycoside hydrolase families 1 and 9 from Coptotermes gestroi

Termites can degrade up to 90% of the lignocellulose they ingest using a repertoire of endogenous and symbiotic degrading enzymes. Termites have been shown to secrete two main glycoside hydrolases, which are GH1 (EC 3.2.1.21) and GH9 (EC 3.2.1.4) members. However, the molecular mechanism for lignocellulose degradation by these enzymes remains poorly understood. The present study was conducted to understand the synergistic relationship between GH9 (CgEG1) and GH1 (CgBG1) from Coptotermes gestroi, which is considered the major urban pest of São Paulo State in Brazil. The goal of this work was to decipher the mode of operation of CgEG1 and CgBG1 through a comprehensive biochemical analysis and molecular docking studies. There was outstanding degree of synergy in degrading glucose polymers for the production of glucose as a result of the endo-β-1,4-glucosidase and exo-β-1,4-glucosidase degradation capability of CgEG1 in concert with the high catalytic performance of CgBG1, which rapidly converts the oligomers into glucose. Our data not only provide an increased comprehension regarding the synergistic mechanism of these two enzymes for cellulose saccharification but also give insight about the role of these two enzymes in termite biology, which can provide the foundation for the development of a number of important applied research topics, such as the control of termites as pests as well as the development of technologies for lignocellulose-to-bioproduct applications.

Biology of invasive termites: a worldwide review

The number of recognized invasive termite species has increased from 17 in 1969 to 28 today. Fourteen species have been added to the list in the past 44 years; 10 have larger distributions and 4 have no reported change in distribution, and 3 species are no longer considered invasive. Although most research has focused on invasive termites in urban areas, molecular identification methods have answered questions about certain species and found that at least six species have invaded natural forest habitats. All invasive species share three characteristics that together increase the probability of creating viable propagules: they eat wood, nest in food, and easily generate secondary reproductives. These characteristics are most common in two families, the Kalotermitidae and Rhinotermitidae (which make up 21 species on the invasive termite list), particularly in three genera, Cryptotermes, Heterotermes, and Coptotermes (which together make up 16 species). Although it is the largest termite family, the Termitidae (comprising 70% of all termite species) have only two invasive species, because relatively few species have these characteristics. Islands have double the number of invasive species that continents do, with islands in the South Pacific the most invaded geographical region. Most invasive species originate from Southeast Asia. The standard control methods normally used against native pest termites are also employed against invasive termites; only two eradication attempts, in South Africa and New Zealand, appear to have been successful, both against Coptotermes species.

Recent speciation in three closely related sympatric specialists: inferences using multi-locus sequence, post-mating isolation and endosymbiont data

Shifting between unrelated host plants is relatively rare for phytophagous insects, and distinct host specificity may play crucial roles in reproductive isolation. However, the isolation status and the relationship between parental divergence and post-mating isolation among closely related sympatric specialists are still poorly understood. Here, multi-locus sequence were used to estimate the relationship among three host plant–specific closely related flea beetles, Altica cirsicola, A. fragariae and A. viridicyanea (abbreviated as AC, AF and AV respectively). The tree topologies were inconsistent using different gene or different combinations of gene fragments. The relationship of AF+(AC+AV) was supported, however, by both gene tree and species tree based on concatenated data. Post-mating reproductive data on the results of crossing these three species are best interpreted in the light of a well established phylogeny. Nuclear-induced but not Wolbachia-induced unidirectional cytoplasmic incompatibility, which was detected in AC-AF and AF-AV but not in AC-AV, may also suggest more close genetic affinity between AC and AV. Prevalence of Wolbachia in these three beetles, and the endosymbiont in most individuals of AV and AC sharing a same wsp haplotype may give another evidence of AF+(AC+AV). Our study also suggested that these three flea beetles diverged in a relative short time (0.94 My), which may be the result of shifting between unrelated host plants and distinct host specificity. Incomplete post-mating isolation while almost complete lineage sorting indicated that effective pre-mating isolation among these three species should have evolved.

Development of a PCR-restriction fragment length polymorphism protocol for rapid detection and differentiation of four cockroach vectors (group I "Dirty 22" species) responsible for food contamination and spreading of foodborne pathogens: public health importance

Assessing the adulteration of food products and the presence of filth and extraneous materials is one of the measures that the U.S. Food and Drug Administration (FDA) utilizes in implementing regulatory actions of public health importance. To date, 22 common pest species (also known as the "Dirty 22" species) have been regarded by this agency as the spreaders of foodborne diseases. We have further categorized the Dirty 22 species into four groups: I has four cockroach species, II has two ant species, III has 12 fly species, and IV has four rodent species. The presence of any Dirty 22 species is also considered an indicator of unsanitary conditions in food processing and storage facilities. In this study, we describe the development of a two-step nested PCR protocol to amplify the small subunit ribosomal gene of group I Dirty 22 species that include four cockroach species: Blattella germanica, Blatta orientalis, Periplaneta americana, and Supella longipalpa, along with the development of a PCR-restriction fragment length polymorphism method for rapid detection and differentiation of these violative species. This method will be utilized when the specimen cannot be identified with conventional microscopic taxonomic methods, especially when only small body parts are separated and recovered from food samples for analysis or when these body parts are in a decomposed state. This new PCR-restriction fragment length polymorphism will provide correct identification of group I Dirty 22 species; this information can then be used in regulation and prevention of foodborne pathogens.

Analysis of the workers head transcriptome of the Asian subterranean termite, Coptotermes gestroi

The lower termite, Coptotermes gestroi (Isoptera: Rhinotermitidae), is originally from Southeast Asia and has become a pest in Brazil. The main goal of this study was to survey C. gestroi transcriptome composition. To accomplish this, we sequenced and analyzed 3003 expressed sequence tags (ESTs) isolated from libraries of worker heads. After assembly, 695 uniESTs were obtained from which 349 have similarity with known sequences. Comparison with insect genomes demonstrated similarity, primarily with genes from Apis mellifera (28%), Tribolium castaneum (28%) and Aedes aegypti (10%). Notably, we identified two endogenous cellulases in the sequences, which may be of interest for biotechnological applications. The results presented in this work represent the first genomic study of the Asian subterranean termite, Coptotermes gestroi.

Multiple incursions and putative species revealed using a mitochondrial and nuclear phylogenetic approach to the Trogoderma variabile (Coleoptera: Dermestidae) trapping program in Australia

The Warehouse beetle, Trogoderma variabile (Coleoptera: Dermestidae), is an internationally significant invasive pest of packed goods and stored grain. When it was first documented in Australia at Griffith, New South Wales, in 1977, an eradication campaign was initiated. After several years and considerable effort, the eradication campaign was abandoned. To monitor the presence and spread of T. variabile, surveys were carried out by government agencies in 1992 and 2002. When survey data was compared, it was concluded that the distribution of morphologically identified T. variabile had doubled in most Australian states. Here, we used samples from the 2002 survey to conduct a phylogenetic study using partial sequences of mitochondrial genes Cytochrome oxidase I and Cytochrome B, and the nuclear gene 18S, to examine the distribution and dispersal of T. variabile and detect the presence of misidentified species. Based on our molecular results, we show that only 47% of the samples analysed were T. variabile, and the remaining were a mixture of six putative species. In addition, T. variabile was found in only 78% of the trapping sites. We discuss the importance of correct diagnosis in relation to the eradication campaign.

Coptotermes gestroi (Isoptera: Rhinotermitidae) in Brazil: possible origins inferred by mitochondrial cytochrome oxidase II gene sequences

The Asian subterranean termite, Coptotermes gestroi, originally from northeast India through Burma, Thailand, Malaysia, and the Indonesian archipelago, is a major termite pest introduced in several countries around the world, including Brazil. We sequenced the mitochondrial COII gene from individuals representing 23 populations. Phylogenetic analysis of COII gene sequences from this and other studies resulted in two main groups: (1) populations of Cleveland (USA) and four populations of Malaysia and (2) populations of Brazil, four populations of Malaysia, and one population from each of Thailand, Puerto Rico, and Key West (USA). Three new localities are reported here, considerably enlarging the distribution of C. gestroi in Brazil: Campo Grande (state of Mato Grosso do Sul), Itajaí (state of Santa Catarina), and Porto Alegre (state of Rio Grande do Sul).

Interspecific competition and territory defense mechanisms of Coptotermes formosanus and Coptotermes gestroi (Isoptera: Rhinotermitidae)

Coptotermes formosanus Shiraki and C. gestroi (Wasmann) are the most widely distributed species of the genus and occur sympatrically in the subtropics. Results of two bioassays in the current study showed that C. gestroi was more aggressive than C. formosanus. In the petri-dish bioassays, C. gestroi won most of the agonistic encounters over C. formosanus. In the two-dimensional foraging arena bioassays, over 73% tunnel interceptions observed in the 18 replications were caused by progressing tunnels of C. gestroi encountering the tunnels of C. formosanus. Tunnel interception of the two species resulted in minor agonistic interactions. Both species quickly buried the connected tunnel at multiple locations. Termite cadavers resulting from agonistic behavior appeared to have induced sand deposition that resulted in tunnel blockages and deterred reopening of these blockages. Sealing individual tunnels in response to encounters with other species acts to prevent further agonism and mortality, and on a broad scale, the aggregate of such blocked tunnels may come to define the borders between adjacent colonies.

Compensatory base changes illuminate morphologically difficult taxonomy

Compensatory base changes (CBCs) in the ribosomal RNA (rRNA) internal transcribed spacer 2 (ITS2) secondary structures have been used to successfully verify the taxonomy of closely related species. CBCs have never been used to distinguish morphologically indistinct species. Under the hypothesis that CBCs will differentiate species in higher eukaryotes, novel software for CBC analysis was applied to morphologically indistinguishable insect species in the genus Altica. The analysis was species-specific for sympatric Altica beetles collected across four ecoregions and concordant with scanning electron microscopy data. This research shows that mining for CBCs in ITS2 rRNA secondary structures is an effective method for eukaryotic taxon analysis.

Biology of subterranean termites: insights from molecular studies of Reticulitermes and Coptotermes

Molecular genetic techniques have made contributions to studies on subterranean termites at all levels of biological organization. Most of this work has focused on Reticulitermes and Coptotermes, two ecologically and economically important genera. DNA sequence data have significantly improved our understanding of the systematics and taxonomy of these genera. Techniques of molecular biology have provided important new insights into the process of caste differentiation. Population genetic markers, primarily microsatellites, have furthered our understanding of the life history, population biology, community ecology, and invasion biology of subterranean termites. Recent results on the behavioral ecology of subterranean termites reveal a picture different from long-held views, especially those concerning colony breeding structures and foraging ranges. As additional molecular tools and genomic resources become available, and as more subterranean termite researchers incorporate molecular techniques into their approaches, we can expect accelerating advances in all aspects of the biology of this group.

From speciation to introgressive hybridization: the phylogeographic structure of an island subspecies of termite, Reticulitermes lucifugus corsicus

Background

Although much research has been carried out into European Reticulitermes taxonomy in recent years, there is still much discussion about phylogenetic relationships. This study investigated the evolution from intra- to interspecific phylogeny in the island subspecies Reticulitermes lucifugus corsicus and threw new light on this phenomenon. An integrative approach based on microsatellites and mitochondrial and nuclear DNA sequences was used to analyze samples taken from a wide area around the Tyrrhenian sea and showed how the subspecies evolved from its origins to its most recent form on continental coasts.

Results

According to mitochondrial phylogeny and molecular clock calculations, island and continental taxa diverged significantly by vicariance in the Pleistocene glacial period. However, more recently, numerous migrations, certainly human-mediated, affected the structure of the populations. This study provided evidence of direct hybridization and multiple introgressions which occurred in several hybrid areas. Analysis using STRUCTURE based on microsatellite data identified a population in Provence (France) which differed considerably (Fst = 0.477) from populations on the island of Corsica and in Tuscany in the Italian peninsula. This new population, principally distributed in urban areas, is highly heterogeneous especially within the ITS2 regions where homogenization by concerted evolution does not appear to have been completed.

Conclusion

This study provides an unusual picture of genetic interaction between termite populations in the Tyrrhenian area and suggests that more attention should be paid to the role of introgression and human impact on the recent evolution of European termites.