白蚁与动物及微生物的共生类型及其机制

综述了白蚁螱客的主要种类、共生关系及相关机制的研究进展。白蚁螱客中,已报道的动物种类达170种。在与动物的共生关系中存在偏利共生（宾主共栖和异种共栖）、互利共生和无关共生三种;在与微生物的共生关系中,存在与内生菌（原生动物、细菌、真菌和放线菌）和外生菌（蚁巢伞菌等）间的互利关系。指出了白蚁与螱客研究中存在的问题,给出了解决方案,并提出了今后可能的研究热点或方向,为白蚁的综合利用（如纤维素酶）及今后研究物种间的协同进化提供了基础资料。     

Isolation and characterization of 10 microsatellite loci in the magnetic termite,Amitermes meridionalis (Isoptera: Termitidae)

The elongated mounds of the ‘magnetic termite’, Amitermes meridionalis are a prominent feature of the Northern Territory in Australia. They are restricted to habitat patches of seasonally flooded plains which are largely isolated from each other. To investigate the population structure of A. meridionalis, we developed 10 polymorphic microsatellite loci. We tested the variability of the markers on at least 20 individuals from two populations. We found three to 12 alleles per locus with a level of heterozygosity at each locus ranging from 0.05 to 0.74.     

Asexual queen succession in the higher termite Embiratermes neotenicus

Asexual queen succession (AQS), in which workers, soldiers and dispersing reproductives are produced sexually while numerous non-dispersing queens arise through thelytokous parthenogenesis, has recently been described in three species of lower termites of the genus Reticulitermes. Here, we show that AQS is not an oddity restricted to a single genus of lower termites, but a more widespread strategy occurring also in the most advanced termite group, the higher termites (Termitidae). We analysed the genetic structure in 10 colonies of the Neotropical higher termite Embiratermes neotenicus (Syntermitinae) using five newly developed polymorphic microsatellite loci. The colonies contained one primary king accompanied either by a single primary queen or by up to almost 200 neotenic queens. While the workers, the soldiers and most future dispersing reproductives were produced sexually, the non-dispersing neotenic queens originated through thelytokous parthenogenesis of the founding primary queen. Surprisingly, the mode of thelytoky observed in E. neotenicus is most probably automixis with central fusion, contrasting with the automixis with terminal fusion documented in Reticulitermes. The occurrence of AQS based on different mechanisms of ploidy restoration raises the hypothesis of an independent evolutionary origin of this unique reproductive strategy in individual lineages of lower and higher termites.     

Chemical warfare in termites

The rapid development of analytical methods in the last four decades has led to the discovery of a fascinating diversity of defensive chemicals used by termites. The last exhaustive review on termite defensive chemicals was published by G.D. Prestwich in 1984. In this text, we aim to fill the gap of the past 25 years and overview all of the relevant primary sources about the chemistry of termite defense (126 original papers, see Fig. 1 and online supplementary material) along with related biological aspects, such as the anatomy of defensive glands and their functional mechanisms, alarm communication, and the evolutionary significance of these defensive elements.     

Repeated copulation and testes enlargement in Macrotermes michaelseni

ABSTRACT. The minimal copulation frequency of the reproductives of Macrotermes michaelseni (Sjöstedt) was investigated by removing the king from incipient laboratory colonies and from mature field colonies. Laboratory females stopped producing fertile eggs 56–154 days, and physogastric queens from field colonies less than 13 days after the removal of the king. Compared with young laboratory male reproductives, kings from mature field colonies are reported to have enormously enlarged testes, larger corpora allata (CA) and a higher juvenile hormone (JH) titre. However, JH application to young males did not increase the volume of the testes. The testes volumes only increased if the males were kept with additional workers or if their incipient colonies were allowed to grow continuously under unrestricted space conditions. These males also had bigger CA, and the soil in their midgut was replaced by food from the workers. It is concluded that in a growing colony the king is differently fed by the increasing number of workers and that trophic change in combination with higher CA activity induce enlargement of the testes. These enlarged testes are able to produce the sperm to fertilize the large number of eggs laid by a physogastric queen.     

Interspecific variation in the defence secretions of Nasutitermes soldiers

Termite soldiers of the genus Nasutitermes (Isoptera, Termitidae, Nasutitermitinae) eject a viscous, sticky defense secretion composed of non-polar monoterpene hydrocarbons and polyoxygenated diterpenes from the frontal gland. Chemical compositions are described in detail for the East African species, N. kempae and N. infuscatus, and for the Neotropical species N. ephratae. Additional comparisons with the new world species N. costalis, N. rippertii and N. octopilis are presented. The structure of a new monohydroxykempene from N. ephratae is described, and a physicochemical model for the stickiness of the glue is presented. Although the structures of the individual secretion components vary within the genus, the glue-like nature of the secretion remains essentially unchanged. Chemical analysis of soldier defense secretions may be useful in studying the systematic biology of termites.     

Chemical variation in defensive secretions of four species of Nasutitermes

Nineteen monoterpenes and 13 diterpenes were distinguished in soldier defensive secretions of four species of Nasutitermes. Samples of N. columbicus, N. corniger, N. ephratae and N. nigriceps were collected in Costa Rica and Panama. Interspecifically, these species can be differentiated by monoterpenes, which exhibit a complex pattern. Intraspecifically, there is detectable variation in monoterpenes and diterpenes, each of which allows discrimination of four populations of N. corniger. Similarity between two Pacific populations of N. corniger from different environments, a tropical dry forest and a rainforest, suggests there is no climatic influence on chemical compositions of defensive secretions. In addition, results from Costa Rica provide evidence that the Atlantic population of N. corniger is derived from Pacific populations.     

Chemotaxonomy of Subulitermes and Nasutitermes termine soldier defense secretions. Evidence against the hypothesis of diphyletic evolution of the Nasutitermitinae

The soldier defense secretions of advanced neotropical termites of the genus Subulitermes (Isoptera, Nasutitermitinae) contain diterpenes identicalto those found in Nasutitermes species, while soldiers of the primitive mandibulate nasute genera Cornitermes, Armitermes and Rhynchotermes lack diterpenoid compounds. It now appears improbable that the elongate nasus and intimately associated terpenoid defense secretions evolved from a primitive mandibulate ancestor independently along two phyletic branches. An alternate hypothesis is proposed in which morphological divergence from a common diterpene-producing ancestor may have occurred.     

Morphology and molecular phylogeny of Pseudotrichonympha hertwigi and Pseudotrichonympha paulistana (Trichonymphea, parabasalia) from neotropical rhinotermitids

Pseudotrichonympha is a large hypermastigote parabasalian found in the hindgut of several species of rhinotermitid termites. The genus was discovered more than 100 years ago, and although over a dozen species have since been described, this represents only a small fraction of its likely diversity: the termite genera from which Pseudotrichonympha is known are all species rich, and in most cases their hindgut symbionts have not been examined. Even formally described species are mostly lacking in detailed microscopic data and/or sequence data. Using small subunit ribosomal RNA gene sequences and light and scanning electron microscopy we describe here the morphology and molecular phylogenetic position of two Pseudotrichonympha species: the type species for the genus, Pseudotrichonympha hertwigi from Coptotermes testaceus (described previously in line drawing only), and Pseudotrichonympha paulistana from Heterotermes tenuis (described previously based on light microscopy only).     

Gut content analysis and a new feeding group classification of termites

1. Gut content analysis of termites was undertaken using microscopical techniques. The 46 study species covered the entire range of taxonomic and feeding forms within the Order. 2. Inter‐specific gut contents data were analysed using principal components analysis, placing species along a clear humification gradient based on variations in the amount of silica and plant tissue fragments in the gut. 3. Redundancy analysis was used to find morphological correlates of the observed variation in gut contents. A total of 22 morphological characters (out of 45 candidate characters) were correlated significantly with the gut contents. 4. Three of the 22 significantly correlated characters unambiguously defined feeding groups, which were designated groups I to IV in increasing order of humification of the feeding substrate. Group I contains lower termite dead wood and grass‐feeders; group II contains Termitidae with a range of feeding habits including dead wood, grass, leaf litter, and micro‐epiphytes; group III contains Termitidae feeding in the organic rich upper layers of the soil; group IV contains the true soil‐feeders (again all Termitidae), ingesting apparently mineral soil. These groupings were generally supported statistically in a canonical covariance analysis, although group II apparently represents termite species with a rather wide range of feeding habits. 5. Using existing hypotheses of termite phylogenetic relationships, it seems probable that group I feeders are phylogenetically basal, and that the other groupings have arisen independently on a number of occasions. Soil‐feeding (i.e. group III and group IV feeding) may have evolved due to the co‐option of faecal material as a fungal substrate by Macrotermitinae‐like ancestral forms. As a consequence, these forms would have been constrained to build nest structures from soil and would therefore have passed at least some soil through their guts.     

Are the spatio‐temporal dynamics of soil‐feeding termite colonies shaped by intra‐specific competition?

1. Soil‐feeding termites are abundant and diversified in neotropical forests, where they are among the major decomposers of the soil macrofauna. While niche specialisation along the humification gradient may reduce inter‐specific competition, some species are represented by numerous colonies likely to be involved in intra‐specific competition, but the subterranean nesting habits of most species of soil‐feeding termites make direct observations difficult. 2. The soldierless species Anoplotermes banksi Emerson was studied, which, unlike other Anoplotermes‐group species, builds arboreal nests that can be easily detected. To infer the biological processes driving the spatial distribution of this species, we conducted a 3‐year survey of the dynamics of colonisation of a 1‐ha plot by A. banksi. Ripley's L‐function, detecting aggregation or dispersion at various spatial scales, was used to investigate the distribution pattern of A. banksi nests, as well as the distribution of new and established nests. 3. Only one‐fourth of the nests recorded the first year were still alive after 3 years, highlighting a rapid turnover of the A. banksi nest population. Age classes were differentially affected by mortality, which was higher in young nests than in large, established nests. 4. Established nests were overdispersed at a short range, whereas young nests had a random or clumped distribution. Young nests tended to be overdispersed from established ones and were more abundant in areas with recently dead nests. Dead nests predominantly occurred where A. banksi nests were particularly abundant. Altogether, the present results indicate a negative interaction between neighbouring colonies suggesting intra‐specific competition.