A novel hypothesis for the origin of the sexual division of labor in termites: which sex should be soldiers?

Sexual specialization and skewed sex ratios of the altruistic castes, especially soldiers, are common in many termite taxa. However, no theoretical or empirical studies have explained the origin of the sexual division of labor in termites. In most termite species, female alates are larger than male alates, and mature queens are much larger than kings, with females under consistent selection for high fertility. Therefore, females usually have the potential to be larger than males. Here, I present a novel preadaptation hypothesis that potential sexual differences in the suitability for the caste give rise to the sexual division of labor, and I provide the first evidence in support of this hypothesis in termites. Defense in Reticulitermes is typically performed by soldiers via mandibular and phragmotic defense in which soldiers with pluglike heads block openings, thus preventing enemies from invading the nest. Phragmotic defense requires that soldiers have heads wide enough to plug nest openings. Therefore, a size threshold for workers that develop into soldiers is a likely adaptation for effective defense. I show that sexual size dimorphism (SSD) and a size threshold for soldiers promote skewed sex ratios. A female-biased soldier sex ratio was observed in species with SSD, whereas there was no bias in soldier sex ratio in species without SSD. Thus, SSD and soldier sex ratio data from several Reticulitermes species support the preadaptation hypothesis.     

Nutrition of the Tamandua: I. Nutrient composition of termites (Nasutitermes spp.) and stomach contents from wild tamanduas (Tamandua tetradactyla)

Arboreal termites (Nasutitermes spp.) and stomach contents from tamanduas (Tamandua tetradactyla) were collected in central Venezuela during the mid part of the dry season (March) of 1993 and 1994. Nutritional analyses were performed on each caste (workers n = 3), soldiers (n = 5), and alates [n = (1]), on mixed caste samples (n = 1), and on stomach contents from live (n = 5) and roadkill (n = 5) tamanduas. The chemical analysis, expressed on a dry matter (DM) basis, of termite workers, which constituted the majority of the nest populations, showed the highest crude protein (CP) (67%) and the lowest DM (25%) and fat (2%) values. Ash content varied from a low of 4% in alates to a high of 7% in soldiers. The alates contained substantially higher DM (41%) and fat (40%), which was reflected in a higher caloric value (6.88 kcal/g) (gross energy) [GE], and relatively less CP (49%). Among the macrominerals, potassium (K) was consistently the highest, with an overall mean value of 0.54%, while the calcium (Ca) and phosphorus (P) levels showed overall means of 0.26% and 0.67%, respectively. Iron (Fe) was the highest among the trace minerals but highly variable (soldiers, 1,000 ppm; alates, 246 ppm; workers, 394 ppm). Differences in the concentrations of vitamin A and E were found among termites castes, with soldiers showing the highest values (20 and 85 μg/g for retinol and α-tocopherol, respectively). Acid detergent fiber (ADF) was lower in the alates (13%) and workers (27%) compared to the soldiers (35%). Alates' fat was more saturated (39%), while soldiers and workers had a much higher polyunsaturated fatty acid (PUFA) concentration. In general, similar nutrient profiles were found between the tamandua stomach contents and the overall mean composition of Nasutitermes spp. However, stomach contents had much higher ADF, ash, and Fe concentrations (31%, 14%, and 2,748 ppm) than termites (25%, 5%, and 652 ppm) but lower CP, fat, GE, and Ca values (51%, 11%, 4.58 kcal/g, and 0.11% vs. 58%, 15%, 6.01 kcal/g, and 0.26% in termites). The relatively low concentrations of Ca in both stomach contents and termites may be indicative of a low requirement in Myrmecophaga compared to other mammalian species. Diets consumed by free-ranging tamanduas contained on a DM basis 51% CP, 11% fat, 14% ash, 31% ADF, 4.58 kcal/g GE, 0.11% Ca, 0.41% P, 2.52 μg/g retinol, and 44.3 μg/g α-tocopherol. Duplication of these nutrient profiles might greatly benefit captive health and reproduction of this species. © 1996 Wiley-Liss, Inc.     

Arolia in termites (Isoptera): functional significance and evolutionary loss

Summary. Termite workers from all families examined had no arolia (=adhesive pads) on their tarsi and are unable to climb smooth vertical surfaces such as glass or polypropylene plastic. This contrasts with ants where both workers and alates of most species possess arolia and are able to climb these surfaces. Arolia were present in alates of the majority of species investigated from three of the four most basal termite families (Mastotermitidae, Termopsidae and Kalotermitidae), though absent from the basal family Hodotermitidae that contains only three genera. Alates in the two kalotermitid species tested readily climbed glass walls. The complete evolutionary loss of arolia from alates in the specious two most apical termite families (Rhinotermitidae and Termitidae) suggests paedomorphosis. Very smooth surfaces probably cannot be used to completely prevent entry of rhinotermitid termites into buildings because these termites can eventually build galleries of feces and soil over these surfaces. However, an experiment with Coptotermes formosanus showed that a smoother surface significantly slows down the rate of gallery building.Received 12 February 2004; revised 17 June 2004; accepted 29 June 2004.     

Review of bees as guests in termite nests,with a new record of the communal bee, <Emphasis Type="Italic">Gaesochira obscura</Emphasis> (Smith, 1879) (Hymenoptera,Apidae), in nests of <Emphasis Type="Italic">Anoplotermes banksi</Emphasis> Emerson, 1925 (Isoptera,Termitidae, Apicotermitinae)

Associations between bees and termites are documented infrequently, but records are available for bee species ranging in behavior from solitary to highly eusocial. The subtribe Meliponina (stingless bees) is the most common bee group reported in termite nests, and, for some species, the occupancy of termite nests may be obligatory. The records of solitary bees nesting within termite nests include species of the tribes Emphorini, Centridini, Megachilini, and Paracolletini. Most of these bees can probably nest in other substrates, and their relationships with termite nests are presumably opportunistic. This study provides a review of published records of bees as guests in termite nests, and also describes the aggregation of nests of Gaesochira obscura within one nest of Anoplotermes banksi in Brazilian Amazonia. One termite nest contained at least ten nest entrances of G. obscura, with burrows 4–6 mm in diameter and about 10 cm long. Each burrow ended in brood cells in different stages of food provisioning and larval development. As commonly reported for other associations of this nature, there was no connection between the tunnels of bees and those of termites. This record adds important data on the biology of A. banksi. Because this is a single record, it is impossible to classify G. obscura either as a termitophile or termitariophile; this species may be opportunistic in relation to nesting substrate.     

Driver Ants Invading a Termite Nest: Why Do the Most Catholic Predators of All Seldom Take This Abundant Prey?

Driver ants ( i.e. , epigaeic species in the army ant genus Dorylus , subgenus Anomma ) are among the most extreme polyphagous predators, but termites appear to be conspicuously absent from their prey spectrum and attacks by driver ants on termite nests have not yet been described. Here, we report a Dorylus ( Anomma ) rubellus attack on a colony of the fungus-growing termite Macrotermes subhyalinus that was observed during the dry season in a savannah habitat in Nigeria's Gashaka National Park. It was estimated that several hundred thousand termites (probably more than 2.4 kg dry mass) were retrieved. The apparent rarity of driver ant predation on Macrotermes nests may be explained by different habitat requirements, by the fact that these ants mostly forage aboveground, by efficient termite defense behavior and nest architecture that make entry into the nest difficult, and finally by driver ant worker morphology, which differs remarkably from that of subterranean Dorylus species that regularly invade and destroy termite colonies.     

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.     

Isolation and characterization of norharmane from Reticulitermes termites (Isoptera: Rhinotermitidae)

The fluorescent alkaloid norharmane has been isolated from Reticulitermes termites and characterized by 1H NMR, UV/Vis, mass spectrometry, and gas chromatography/mass spectrometry. Microcoil 1H NMR spectroscopy allowed spectra to be obtained from mass-limited material, facilitating the identification of norharmane, which is the major component in termite fluorescence under UV light. Norharmane was uniformly present at approximately 1 ng/mg in Reticulitermes tibialis Banks workers, soldiers, and alates; Reticulitermes flavipes (Kollar) workers; and Reticulitermes virginicus (Banks) workers. Some termites were observed to fluoresce with less intensity, but no differences in norharmane levels were detected. Mechanisms that may account for fluorescent differences are discussed as are the possible ecological implications of norharmane in termites.     

Observations on the foraging activity of Hospitalitermes umbrinus (Haviland), (Isoptera: Termitidae) in the Gunong Mulu National Park, Sarawak

Abstract. 1. A single nest of the black surface-foraging nasute termite Hospitalitermes umbrinus was studied for 5 days in July 1978. Foraging parties of workers and soldiers tend to leave the nest in a continuous stream in the evening and return carrying food balls during the following morning.
2. An estimated maximum of 500000 individuals were involved in the foraging excursions. At a density of 3 nests ha^-1, the total foraging population is estimated as being at least 180 m^-2.
3. The colony brought back an estimated 46.4 g (d.w.) of food in 4 days. The biomass of the colony was estimated at 349 g (d.w.) ( c. 1396 g w.w.) excluding alates and the consumption at 8.3 mg (d.w.) g^-1 (w.w.) d^-1.
4. The food balls were found to be of two types, light and dark coloured. The light balls contained wood constituents, bryophytes, blue-green algae and fungal hyphae while the dark balls consisted mainly of lichens and their spores.
5. Swarming began at 14.30 hours on 9 July and ended with the nuptial flight at 17.32 hours. About 3000 alates were released. They climbed to 9 m on a tree before taking off.     

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.     

Levels of specificity of Xylaria species associated with fungus-growing termites: a phylogenetic approach

Fungus-growing termites live in obligate mutualistic symbiosis with species of the basidiomycete genus Termitomyces , which are cultivated on a substrate of dead plant material. When the termite colony dies, or when nest material is incubated without termites in the laboratory, fruiting bodies of the ascomycete genus Xylaria appear and rapidly cover the fungus garden. This raises the question whether certain Xylaria species are specialised in occupying termite nests or whether they are just occasional visitors. We tested Xylaria specificity at four levels: (1) fungus-growing termites, (2) termite genera, (3) termite species, and (4) colonies. In South Africa, 108 colonies of eight termite species from three termite genera were sampled for Xylaria . Xylaria was isolated from 69% of the sampled nests and from 57% of the incubated fungus comb samples, confirming high prevalence. Phylogenetic analysis of the ITS region revealed 16 operational taxonomic units of Xylaria , indicating high levels of Xylaria species richness. Not much of this variation was explained by termite genus, species, or colony; thus, at level 2–4 the specificity is low. Analysis of the large subunit rDNA region, showed that all termite-associated Xylaria belong to a single clade, together with only three of the 26 non-termite-associated strains. Termite-associated Xylaria thus show specificity for fungus-growing termites (level 1). We did not find evidence for geographic or temporal structuring in these Xylaria phylogenies. Based on our results, we conclude that termite-associated Xylaria are specific for fungus-growing termites, without having specificity for lower taxonomic levels.     

小头钩白蚁巢结构研究

【目的】了解小头钩白蚁Ancistrotermes dimorphus Tsai et Chen的蚁巢结构、各品级在腔室中的分布和巢群个体数量,为有效防控该种白蚁提供科学依据。【方法】采用蚁巢定位和巢体结构解剖法研究蚁巢结构;采用统计法确定各品级在腔室中的分布和巢群个体数量。【结果】小头钩白蚁巢由腔室、菌圃、蚁路、王室、候飞室和分飞孔六部分组成;巢群个体数量为12 255~24 230头(含卵粒);卵、幼蚁、若蚁、工蚁、兵蚁和有翅成虫分散分布在蚁巢腔室中,并不集中于某一特定区域。【结论】小头钩白蚁巢属于极端分散类型,巢群个体数量较少。     

红火蚁的巢间相容性

在室内条件下通过将红火蚁Solenopsis invicta Buren异巢不同品级的个体置于同一容器中,对红火蚁的巢间相容性进行研究。结果表明,蚁后与异巢幼蚁共处时,异巢幼蚁的羽化率为33.3%,与对照处理的38.3%(蚁后与同巢幼蚁共处)无显著差异。工蚁与异巢幼蚁共处时,异巢幼蚁的羽化率为53.7%,与对照处理的72.2%(工蚁与同巢幼蚁共处)无显著差异。蚁后与异巢工蚁共处时,异巢蚁后的存活率为45%,与对照处理的61.7%(工蚁与同巢蚁后共处)无显著差异。有翅繁殖雌蚁与异巢工蚁共处时,异巢工蚁的存活率为86.7%与对照处理的99.4%(工蚁与同巢有翅繁殖雌蚁共处)存在显著差异;异巢有翅雌蚁的存活率为22.2%,与对照处理的88.9%(工蚁与同巢有翅繁殖雌蚁共处)存在显著差异。由此可见,同区域内红火蚁异巢各品级间存在一定程度的相容性,并巢行为有可能发生。     

Biomass and population structure of Constrictotermes cyphergaster (Silvestri) (Isoptera: termitidae) in the dry forest of caatinga, northeastern Brazil

Biomass and population structure of Constrictotermes cyphergaster (Silvestri) were studied in an area of dry forest of caatinga in the State of Paraiba, northeastern Brazil. Twelve nests of different sizes were randomly collected, being six during the dry season (November 2004 and 2005) and six during the wet season (March 2004). Soldier and worker populations varied between 4880 and 118800 individuals per nest. The ratio between soldiers and workers did not significantly vary between seasons. Biomass (measured as fresh weight) of individuals varied between 13.9 and 408.8 g per nest, and soldiers and workers had significantly greater biomass during the wet season. The estimated density of nests of C. cyphergaster was 59.0 +/- 22.53 active nests/ha. Quantitative data of the study colonies and data on the nest abundance showed that C. cyphergaster encompassed some 278.2 individuals/m(2), with approximately 0.9 g (fresh weight)/m(2). These data suggest that C. cyphergaster is an important consumer of vegetal matter and, therefore, an important species affecting the nutrient cycling and energy flow in the caatinga vegetation.     

Seasonal patterns of nitrogen fixation in termites

1. Termite nitrogenase activity was highest in autumn and spring (≈ 3 μg N₂ fixed termite fresh mass (g)^–1 day^–1) and lowest in winter and summer (≈ 0·8 μg N₂ fixed termite fresh mass (g)^–1 day^–1).
2. The nitrogenase activity of worker termites was significantly higher than all other castes (1·58 ± 0·27 μg N₂ fixed termite fresh mass (g)^–1 day^–1).
3. Worker termites constituted the largest proportion of all the castes throughout the study period (≈ 90%).
4. The localized input of fixed nitrogen by termites may reach 15·3 mg N log^–1 day^–1 and 5·6 g N log^–1 year^–1.     

First evidence of wasp brood development inside active nests of a termite with the description of a previously unknown potter wasp species

Potter wasps (Vespidae: Eumeninae) are known to exhibit not only sophisticated preying strategies but also a remarkable ability to manipulate clay during nest building. Due to a mixture of plasticity in building behavior and flexibility in substrate preferences during nest building, the group has been reported nesting in a variety of places, including decaying nests abandoned by termite species. Yet, evidence of wasps nesting inside senescent termite mounds is poorly reported, and to date, accounts confirming their presence inside active colonies of termites are absent. Here, we address a novel intriguing association between two species from the Brazilian Cerrado: a previously unknown potter wasp (nest invader) and a termite species (nest builder). Besides scientifically describing Montezumia termitophila sp. nov. (Vespidae: Eumeninae), named after its association with the termite Constrictotermes cyphergaster (Silvestri, 1901) (Termitidae: Nasutitermitinae), we provide preliminary information about the new species'' bionomics by including (a) a hypothetical life cycle based on the evidence we collected and (b) a footage showing the first interaction between a recently ecloded wasp and a group of termites. In doing so, we attempt to provoke relevant discussions in the field and, perhaps, motivate further studies with the group. Finally, we describe a solution to efficiently detect and sample termitophilous species from termite nests, an intrinsic yet challenging task of any studies dealing with such a cryptic biological system.     

A strain of the fungus Metarhizium anisopliae for controlling subterranean termites

Alates of the Formosan subterranean termite, Coptotermes formosanus Shiraki, collected after swarming in 2002 died within 48 h, and the cadavers were visibly infected with a fungus. Fungi were picked from the cadavers, transferred to media, and ultimately isolated to purity. The individual fungal cultures were then used to infect Formosan subterranean termite workers. A single fungal isolate, C4-B, taxonomically identified as Metarhizium anisopliae (Metschnikoff), was found to cause rapid mortality of Formosan subterranean termite alates. This is the first report of a biological control agent for termite alates. In initial experiments, C4-B was more lethal to both alates and workers compared with M. anisopliae strain ESC 1, previously marketed as the termite biocontrol agent BioBlast. Dose-response assays in which Formosan subterranean termite alates were exposed to a known concentration of C4-B spores revealed that 10(6) spores/microl killed 100% of the alates in 3 d, both 10(5) and 10(4) spores/microl in 6 d, 10(3) spores/microl in 9 d, and 10(0) spores/microl in 12 d. Assays with workers demonstrated that 10(6) and 10(5) spores/microl killed 100% of the workers in 6 d. In an experiment to test the transfer of inoculum from infected workers to uninfected nestmates, 62.8% of the workers died in 21 d when only 20% of the workers had been inoculated. Mortality of alates caused by C4-B was tested at two field sites by dispersing fungal spores on grassy lawns and collecting alates from the treated areas. Alates thus infected showed 100% mortality by day 5, whereas only 64.8% of untreated control alates from the same collection area were dead on that day.     

New trace fossils of termites (Insecta: Isoptera) from the late Eocene‐early Miocene of Egypt,and the reconstruction of ancient isopteran social behavior

Three new ichnogenera and five new ichnospecies are described for new trace fossils of termitaria (including associated gallery systems) of subterranean termites from upper Eocene through lower Miocene rocks of northern Egypt. All but two ichnospecies (Krausichnus trompitus, ichnogen, and ichnosp. nov., and A’, altus, ichnosp. nov.) show varying degrees of affinity to nests of the extant subterranean termite species Sphaerotermes sphaerothorax (Termitidae, Macro‐termitinae).

Termitichnus qatranii (Bown, 1982) is divided into two ichnospecies, the previously named T. qatranii, and a more generalized form, T. simplicidens, ichnosp. nov. Vondrichnus obovatus, ichnogen. and ichnosp. nov., is named for simple, possibly macrotermitine nests with oblate form, and Fleaglellius pagodus, ichnogen. and ichnosp. nov., records a nest form similar to V. obovatus, but one in which successive vertical growth by chamber apposition has produced a subterranean, tower‐like structure, reminiscent of that built by extant, epigeous Cubitermes. Krausichnus trompitus, ichnogen. and ichnosp. nov., and A’, altus, ichnosp. nov., record two unique nest architectures probably produced by unknown but related species of humivorous termites. The nest architecture expressed by Krausichnus is of wholly unknown affinity and is only distantly related in form to the ichnofossils of other termite nests known from the Tertiary of Egypt.

Study of the architecture of the nests of these ancient termites reveals details important in reconstructing the phylogeny of termite nests and documents two novel blueprints for chamber expansion and society budding in what were probably primitive Macrotermi‐tinae. It also indicates that at least two constructed edifices, earlier known only as epigeous manifestations of extant termite species, were almost certainly first developed by species living underground.

The extant Macrotermitinae are a subfamily of termites originally believed to have evolved in the post‐Eocene of the Ethiopian biogeo‐graphic region. We offer fossil evidence of four distinct, possibly macrotermitine structures from upper Eocene rocks. This evidence suggests that this termite subfamily (or at least their peculiar mode of nest construction) might have evolved considerably earlier, as it is already well established and exhibits several variants by the late Eocene in Egypt.     

Settlement in the prey termite nest by the ponerine antPachycondyla caffraria (Smith), and tandem running signal analysis for the following ant

The workers ofPachycondyla caffraria attack the nests of the termiteMicrocerotermes sp. in the laboratory. The hunter workers bore into the side of the nest, enter and catch the termites, and return to their nest with the captured prey. Later in the same day, all or part of the colony moves out and settles in the termite nest. The hunter workers use tandem running for the attack of the termite nest, the capture of termite and the removal of the colony to the nest which was raided. To analyse the relevant signals for the following ant during tandem running, we offered different dummies to followers which had been separated from their leader ants. The signals which release the following behaviour are a conbination of visual and chemical signals. Seventy percent of motivated followers reacted positively to paper with methanolic extract of the leader ant, 44% of motivated followers reacted positively to an odourless paper, and 100% reacted positively to a freshly killed leader ant. The leading effect of the body surface is lost by cleaning with solvents of different polarity.     

囟土白蚁蚁后卵巢管数量、蚁巢体积与蚁群中各蚁型数量的相关性

囟土白蚁Odontotermes fontanellus Kemner是安徽为害林木、水库堤坝的主要蚁种。研究结果表明:1.在一定的巢龄范围内,随着蚁后身体增长,卵巢管数量增多,一侧的卵巢管最多可达3726条。2.蚁后体长与工蚁数、兵蚁数、幼蚁数、整巢蚁数之间成幂函数关系。3.卵巢管数与蚁后体长、工蚁数、兵蚁数、幼蚁数、整巢蚁数之间成幂函数关系,4,蚁巢体积(y)与蚁后体长(X_2)、兵蚁数(X_4)、的关系式为:y=6.687e~(0.0566)X_2+0.6741X_4