Drosophila melanogaster is emerging as an important model of non-pathogenic host–microbe interactions. The genetic and experimental tractability of Drosophila has led to significant gains in our understanding of animal–microbial symbiosis. However, the full implications of these results cannot be appreciated without the knowledge of the microbial communities associated with natural Drosophila populations. In particular, it is not clear whether laboratory cultures can serve as an accurate model of host–microbe interactions that occur in the wild, or those that have occurred over evolutionary time. To fill this gap, we characterized natural bacterial communities associated with 14 species of Drosophila and related genera collected from distant geographic locations. To represent the ecological diversity of Drosophilids, examined species included fruit-, flower-, mushroom-, and cactus-feeders. In parallel, wild host populations were compared to laboratory strains, and controlled experiments were performed to assess the importance of host species and diet in shaping bacterial microbiome composition. We find that Drosophilid flies have taxonomically restricted bacterial communities, with 85% of the natural bacterial microbiome composed of only four bacterial families. The dominant bacterial taxa are widespread and found in many different host species despite the taxonomic, ecological, and geographic diversity of their hosts. Both natural surveys and laboratory experiments indicate that host diet plays a major role in shaping the Drosophila bacterial microbiome. Despite this, the internal bacterial microbiome represents only a highly reduced subset of the external bacterial communities, suggesting that the host exercises some level of control over the bacteria that inhabit its digestive tract. Finally, we show that laboratory strains provide only a limited model of natural host–microbe interactions. Bacterial taxa used in experimental studies are rare or absent in wild Drosophila populations, while the most abundant associates of natural Drosophila populations are rare in the lab.

https://escholarship.org/content/qt7343441k/qt7343441k.pdf?t=qajnct

Bacterial communities of diverse Drosophila species: ecological context of a host-microbe model system.

Termites depend on an intricate symbiosis with flagellated protists, archaea and bacteria in their guts for the digestion of lignocellulose. Here, Andreas Brune gives an overview of the diversity of the termite microbiota and highlights important microbial processes in the gut microecosystem and their implications for host nutrition.

Symbiotic digestion of lignocellulose in termite guts

Contributors. Acknowledgements. Preface. Taxonomy and Phylogeny of Termites S. Kambhampati, P. Eggleton. Global Patterns of Termite Diversity P. Eggleton. Characterizing the Ancestors: Paedomorphosis and Termite Evolution C.A. Nalepa, C. Bandi. Early Fossil History of the Termites B.L. Thorne, D.A. Grimaldi, K. Krishna. Diversity and Evolution of Caste Patterns Y. Roisin. Termite Nests: Architecture, Regulation and Defence C. Noirot, J.P.E.C. Darlington. Behavior and Ecology of Foraging in Termites J.F.A. Traniello, R.H. Leuthold. Theories on the Sociality of Termites M. Higashi, N. Yamamura, T. Abe. Introduction to the Symbiosis D.E. Bignell. Ecology of Prokaryotic Microbes in the Guts of Wood and Litter-Feeding Termites J.A. Breznak. Soil-Feeding Termites: Biology, Microbial Associations and Digestive Mechanisms A. Brauman, D.E. Bignell, I. Tayasu. Intracellular Symbiosis in Termites C. Bandi, L. Sacchi. Symbiotic Associations with Protists T. Inoue, O. Kitade, T. Yoshimura, I. Yamaoka. Symbiosis with Fungi C. Rouland-Lefevre. Energy Metabolism in the Termite and its Gut Microbiota M. Slaytor. Population Dynamics of Termites M. LePage, J.P.E.C. Darlington. Termites in Ecosystems D.E. Bignell, P. Eggleton. Global Impact of Termites on the Carbon Cycle and Atmospheric Trace Gases A. Sugimoto, D.E. Bignell, J.A. MacDonald. Termites as Pests of Buildings Nan-Yao Su, R.H. Scheffrahn. Index.

Termites : evolution, sociality, symbioses, ecology

Termite assemblages are considered as complex systems containing species with several modes of feeding and nesting, which have a major though not necessarily dominant role in decomposition and C mineralization processes, and which influence soil properties and structure. Sampling methods for species richness, abundance and biomass and the estimation of food consumption rates are reviewed; transect methods are recommended for biodiversity surveys as they are efficient and have acceptable accuracy. Biases introduced by sampling methods which focus on mounds only and by consumption assays based on baits lead to underestimates of assemblage diversity, abundance and ecological impact. The range of abundance and biomass of termites in major ecosystems and biogeographical regions is discussed and representative data are tabulated. In savanna systems, the turnover of organic matter by termites is roughly comparable to that of mammalian herbivores and bush fires, and as much as 20% of C mineralization may be directly attributed to termites. In forests, absolute C fluxes through populations are generally larger, owing to higher termite biomass, but the relative contribution to C turnover is less. Functional group heterogeneity rather than species richness per se is considered the key link between termite biodiversity and ecosystem functions.

Termites in Ecosystems

Food futurists accept that sustainability-minded humanity will increasingly incorporate insects as alternative protein. The most studied and easily reared species are not necessarily the most sustainable, acceptable, or delicious. Here, we review the literature on the black soldier fly, Hermetia illucens, which is capable of efficiently converting a wide variety of organic materials, from food waste to manure, into insect biomass. They can be grown and harvested without dedicated facilities and are not pestiferous. Their larvae are 42% crude protein and 29% fat, although they are higher in saturated fats than most insects. They do not concentrate pesticides or mycotoxins. They are already grown and recommended for use as animal feed, but with regional legal restrictions on how this is done. For commercial use in human foods, larvae could potentially be milled and converted into a textured protein with a strong flavor. Their biggest advantage over other insects is their ability to convert waste into food, generating value and closing nutrient loops as they reduce pollution and costs. This general advantage is also their greatest disadvantage, for the social stigmas and legal prohibitions against eating organisms that eat waste are added to extant taboos facing insect consumption.

Review of Black Soldier Fly (Hermetia illucens) as Animal Feed and Human Food

A total of 77 species of termites have been reported as structural or agricultural pests in South America. These records are reviewed, with indication of the damage they cause, their pest status, distribution and sources of information. Among these, 40 species are reported as structural pests, 53 species as agricultural pests and 15 species as both. However, only 18 species are considered major pests and the status of most of the others is uncertain. Uncertainty about status is much higher among agricultural pests. Specific taxonomic problems are discussed and distribution maps of the main pest genera and species are presented. The most important structural pests are the introduced Coptotermes havilandi and Cryptotermes brevis and the native Nasutitermes corniger. Reticulitermes was introduced into Uruguay and Chile, where it is the only serious pest. The main agricultural pests are Heterotermes spp., Nasutitermes spp., Cornitermes spp., Procornitermes spp. and Syntermes spp., and the most affected crops are sugarcane, upland rice and eucalyptus.

The pest termites of South America: taxonomy, distribution and status

A number of cophylogenetic relationships between two organisms namely a host and a symbiont or parasite have been studied to date; however, organismal interactions in nature usually involve multiple members. Here, we investigated the cospeciation of a triplex symbiotic system comprising a hierarchy of three organisms -- termites of the family Rhinotermitidae, cellulolytic protists of the genus Pseudotrichonympha in the guts of these termites, and intracellular bacterial symbionts of the protists. The molecular phylogeny was inferred based on two mitochondrial genes for the termites and nuclear small-subunit rRNA genes for the protists and their endosymbionts, and these were compared. Although intestinal microorganisms are generally considered to have looser associations with the host than intracellular symbionts, the Pseudotrichonympha protists showed almost complete codivergence with the host termites, probably due to strict transmissions by proctodeal trophallaxis or coprophagy based on the social behaviour of the termites. Except for one case, the endosymbiotic bacteria of the protists formed a monophyletic lineage in the order Bacteroidales, and the branching pattern was almost identical to those of the protists and the termites. However, some non-codivergent evolutionary events were evident. The members of this triplex symbiotic system appear to have cospeciated during their evolution with minor exceptions; the evolutionary relationships were probably established by termite sociality and the complex microbial community in the gut.

Cospeciation in the triplex symbiosis of termite gut protists (Pseudotrichonympha spp.), their hosts, and their bacterial endosymbionts.

Agroforestry systems are presented as a valuable alternative to pastures to sustain crop production in forested areas. In order to evaluate their effect on soil macroinvertebrate communities, sampling was conducted during the rainy season at four localities located in the Rondonia and Acre states of Brazil. Four land-use systems were selected (fallow, annual crop, agroforestry systems and pasture), and compared to nearby disturbed forests. We used the sampling method recommended by the Tropical Soil Biology and Fertility Programme. Soil macrofauna responded more readily than soil parameters to different cultivation practices. Co-inertia analysis, however, showed a relationship between soil parameters and soil macrofauna. Comparison of communities showed a significant impact of land-use practices. All systems had quite abundant invertebrate communities with relatively low densities in the forest (884 ind. m–2) and in pastures (841 ind. m–2), and higher densities in fallow, agroforestry system and annual crop (1,737–1,761 ind. m–2). Earthworms were dominant in pastures (155 ind. m–2 and 56.2 g m–2 on average), whereas termites thrived better in annual crops and fallows (with respective densities of 1,287 and 816 and biomasses of 2.32 and 1.38 g m–2). Macrofauna communities in agroforestry systems were rather similar to the forest, in spite of higher densities of social insects. The termite:earthworm ratios were very low in pastures (0.2), had similar values in the forest (7.9) and the agroforestry system (8.8), which is much lower than in fallows (20.4) and annual crops (21.4) This study showed that all land-use practices were able to sustain sizeable macrofaunal communities with agroforestry communities rather similar to the those of a disturbed forest.

Effects of land-use system on the soil macrofauna in western Brazilian Amazonia.

A catalog of the living termites of the New World is presented, including all known synonyms, geographical distribution, type depositories, and a selected bibliography. The number of termite genera recorded for the New World is 86, and the number of species 543. The following taxonomical changes are included: Curvitermes projectidens is transferred to Armitermes, and Nasutitermes columbicus is treated as a junior synonym of N. guayanae. Most subspecies are treated as full species. Available names of uncertain taxonomic position are presented in a separate list.

/pdf/catalog-of-the-living-termites-of-the-new-world-insecta-2cmosgkh3z.pdf

Reginaldo Constantino

Papers

The pest termites of South America: taxonomy, distribution and status

Cospeciation in the triplex symbiosis of termite gut protists (Pseudotrichonympha spp.), their hosts, and their bacterial endosymbionts.

Effects of land-use system on the soil macrofauna in western Brazilian Amazonia.

Catalog of the living termites of the new world (Insecta: Isoptera)

Chave ilustrada para identificacao dos generos de cupins (Insecta: Isoptera) que ocorrem no Brasil