Molecular phylogeny reveals the past transoceanic voyages of drywood termites (Isoptera, Kalotermitidae)

Termites are major decomposers in terrestrial ecosystems and the second most diverse lineage of social insects. The Kalotermitidae form the second-largest termite family and are distributed across tropical and subtropical ecosystems, where they typically live in small colonies confined to single wood items inhabited by individuals with no foraging abilities. How the Kalotermitidae have acquired their global distribution patterns remains unresolved. Similarly, it is unclear whether foraging is ancestral to Kalotermitidae or was secondarily acquired in a few species. These questions can be addressed in a phylogenetic framework. We inferred time-calibrated phylogenetic trees of Kalotermitidae using mitochondrial genomes of ∼120 species, about 27% of kalotermitid diversity, including representatives of 21 of the 23 kalotermitid genera. Our mitochondrial genome phylogenetic trees were corroborated by phylogenies inferred from nuclear ultraconserved elements derived from a subset of 28 species. We found that extant kalotermitids shared a common ancestor 84 Ma (75–93 Ma 95% highest posterior density), indicating that a few disjunctions among early-diverging kalotermitid lineages may predate Gondwana breakup. However, most of the ∼40 disjunctions among biogeographic realms were dated at <50 Ma, indicating that transoceanic dispersals, and more recently human-mediated dispersals, have been the major drivers of the global distribution of Kalotermitidae. Our phylogeny also revealed that the capacity to forage is often found in early-diverging kalotermitid lineages, implying the ancestors of Kalotermitidae were able to forage among multiple wood pieces. Our phylogenetic estimates provide a platform for critical taxonomic revision and future comparative analyses of Kalotermitidae.

Asexual queen succession mediates an accelerated colony life cycle in the termite Silvestritermes minutus

Mixed modes of reproduction, combining sexual processes with thelytokous parthenogenesis, occur in all major clades of social insects. In several species of termites, queens maximize their genetic input into nondispersing replacement queens through parthenogenesis, while maintaining genetically diverse sterile offspring and dispersing reproductives via sexual reproduction. This so-called asexual queen succession (AQS) has multiple independent origins and its presumed advantages are diverse as well, ranging from multiplication of colony reproductive potential to extension of its lifespan beyond that of the foundress. However, how AQS shapes colony life cycles under natural conditions remains poorly known. The neotropical termite Silvestritermes minutus inhabits small but conspicuous nests, offering a unique opportunity to investigate the impact of AQS on life history. We report on its breeding system, life cycle and sex allocation using social structure census in 137 nests and genotyping of 12 colonies at 12 microsatellite loci. We show that colonies are established by an outbred pair of primary reproductives. In less than 2 years, the foundress is replaced by multiple neotenic queens, arising mostly through automixis with central fusion. Sterile castes, male and most (93%) female dispersers are produced sexually. Colony reproduction is usually restricted to a single dispersal of alates with unbiased sex ratio, taking place after 3 years. We conclude that S. minutus benefits from AQS to maximize colony growth rate and alate production within a very short life cycle rather than to extend colony lifespan. This highlights the versatile role of AQS in different cases of its polyphyletic origin.

Sesquiterpenes in the frontal gland secretions of nasute soldier termites from New Guinea

In five New GuineaNasutitermes (N. gracilirostris, N. novarumhebridarum, N. torresi, N. triodiae, and an undescribed speciesN. sp.F), we have detected and identified 10 sesquiterpenes. Eight of these compounds (β)-elemene,β-caryophyllene,α-humulene,α-muurolene,γ-selinene,β-selinene, germacrene-A, and γ2-cadinene) were identified by GC and GC-MS (EI). Two uncommon sesquiterpenes, (5R(*), 7R(*), 10S(*))-selina-4(14),11-diene and (5R(*), 7R(*), 10S(*))-selina-3,11-diene, were identified by GC, GC-MS (EI, CI), GC-FTIR, and mono- and bidimensional NMR. Whereas in most species sesquiterpenes are present in low or trace amounts, inN. novarumhebridarum the sesquiterpenic fraction of soldier frontal gland secretion is equal to that of the monoterpenes.

Explosive backpacks in old termite workers

By nature, defensive behavior is risky. In social insects, such behavior is more likely to occur in individuals whose potential for other tasks is diminished. We show that workers of the termite Neocapritermes taracua develop an exceptional two-component suicidal apparatus consisting of copper-containing protein crystals, stored in external pouches, and internal salivary glands. During aggressive encounters, their bodies rupture, and the crystals react with the salivary gland secretion to produce a toxic droplet. Both the amount of defensive substances and the readiness to explode increase with workers' age, as their food-collecting ability declines.

Molecular phylogeny and biogeography of the nasute termite genus Nasutitermes (Isoptera: Termitidae) in the pacific tropics

The nasute termite genus Nasutitermes is widely distributed over all tropical regions. The phylogenetic relationships among 17 Nasutitermes species from the Pacific tropics were inferred from sequences of mitochondrial cytochrome oxidase II and 16S ribosomal RNA genes. Several methods of analysis yielded phylogenetic trees showing almost the same topology and in good agreement with reconstructions based on morphological or behavioral characters. Neotropical and Australian species came out as separate, apical clades. Asian species split between an apical branch, appearing as sister group to the neotropical clade, and basal taxa. New Guinean species were spread among several clades, suggesting a derivation from multiple origins. A well-supported clade includes the neotropical, Australian, and New Guinean species, with the southeast Asian N. takasagoensis and N. matangensis. It excludes the Asian species N. regularis, N. parvonasutus, and N. longinasus, which might deserve to be removed from Nasutitermes, as well as the long-legged Asian genera Hospitalitermes and Longipeditermes. A Gondwanan origin is proposed for the former clade, although an Old World origin of Nasutitermes followed by dispersal to Australia and South America cannot be excluded.

The nasute termites (Isoptera : Nasutitermitinae) of Papua New Guinea

The Nasutitermitinae fauna of Papua New Guinea is revised, based on collections from most regions of the country. A total of 22 species is reported, 12 of which are new. The genus Nasutitermes Dudley is represented by the following species: N. triodiae (Froggatt), N. torresi (Hill), N. motu, sp. nov., N. princeps (Desneux), N. koiari, sp. nov., N. pinocchio, sp. nov., N. novarumhebridarum (N. & K. Holmgren), N. nomadensis, sp. nov., N. polygynus Roisin & Pasteels, N. bikpelanus, sp. nov., N. gracilirostris (Desneux), N. leponcei, sp, nov., N. muli, sp. nov., N. seghersi, sp. nov., and N. seghersi malangganus, subsp. nov. Niuginitermes, gen. nov., is created for two species: N. variratae, sp. nov., and N. liklik, sp. nov. Diwaitermes, gen. nov., includes D. kanehirae (Oshima), comb. nov., D. foi, sp. nov., and D. castanopsis, sp. nov. A single species of Tumulitermes Holmgren, T. marcidus (Hill), is newly reported from mainland New Guinea. Grallatotermes Holmgren and Hospitalirermes Holmgren are each represented by one species, G. grallator (Desneux) and H. papuanus Ahmad. All known imagos (18 species) as well as soldiers and workers of all species are described and illustrated. For each species, the known geographic distribution within Papua New Guinea is reported. An identification key, based on soldiers and workers, is also provided.

Biosynthesis of tetraponerine-8, a defence alkaloid of the ant Tetraponera sp

The administration of sodium [1-14C] and [2-14C] acetate, L-[U-14C] glutamic acid, &([a-z]+);-amino [U-14C] butyric acid, L-[U-14C] ornithine hydrochloride, and [1,4-14C] putrescine dihydrochloride to Tetraponera sp. ants resulted in the formation, for each feeding experiment, of labelled tetraponerine-8 (2). The distribution of radioactivity into 2 was established by chemical degradation. The results obtained favor the hypothesis that the pyrrolidine ring of tetraponerine-8 is derived from L-glutamic acid via L-ornithine and putrescine, while the 12-carbon chain is derived from the combination of six acetate units.